Theory of Adhesives?

On Mon, 11 Jul 2011 22:54:49 -0400, "Existential Angst" <[email protected]>
wrote:

>Awl --
>
>Previously (on RW), I asked about coatings, waterproofing plywood.
>
>Now, in an interior environment (moisture not an issue), I'm curious about
>laminating an approx. 4' x 6' area of plywood with some other thin-ish, or
>even not so thin-ish material -- from formica laminates, to .030 SS or Alum
>sheet, to 1/4" rubberized tile, linoleum.
>
>I recall carpenters using gobs of white elmers glue for large-contact wood
>areas, in building mezzanines in lofts, etc.
>Then there is elmer's carpenter's/wood glue, mastics for tile (what's a
>mastic, inyway??), epoxies, a zillion other adhesives.
>
>The general Q is: when to use what for what?
>
>For example, in the .030 SS/Alum I will place over 1/2" ply, I would like to
>be able to just roll on some suitable adhesive over the full 4x6 area, and
>press them together, proly via weight plates.
>What would good choices be? How thick?
>
>Interestingly, an increase in thickness from ..5 to .532 will generate about
>a 13% increase in stiffness, since stiffness is proportional to the square
>of thickness, but ONLY if there is no slippage between the two layers.
>Thus, the requirement for full-surface bonding, via adhesive.
>
>Ackshooly, that 13% inc in stiffness presumes similar materials. I measured
>that 1/4" alum plate is as stiff or stiffer than decent 1/2" ply, so the
>increase in stiffness is likely to be a bit more than 13%.
>
>Inyway, I'd like an idea of how to gauge the type of adhesive to
>application. Bang fer the buck is always good, as well.
>
>Along these lines, I see all kinds of two-part epoxies, specialized for
>wood, metal, ceramics/glass, etc.
>Afaict, they all work the same on everything, with perhaps the exception of
>things like nylon, delrin, other "greasy" plastics. Any opinions on this?

When I worked on diesel locomotive equipment, we used to use various types of
caulk to glue all the parts inside various chassis, such as transformers and
filter caps in power supplies. We did this because the vibration would break
everything loose - you would find large parts rolling around inside the chassis
if you didn't!

We started with official GE RTV sealant but eventually just bought household
silicon bath caulk at the hardware store because it was cheaper!! When you
needed to replace something it was easy to cut the stuff with a knife and pull
it off. We even used it on high voltage strobe lights.

We used that shit to glue everything!

On Tue, 12 Jul 2011 01:06:07 -0400, Ed Huntress wrote:

> "Tim" <[email protected]> wrote in message
> news:[email protected]...
>> On Mon, 11 Jul 2011 23:23:50 -0400, Ed Huntress wrote:
>>
>>> "Existential Angst" <[email protected]> wrote in message
>>> news:[email protected]...
>>>> Awl --
>>>>
>>>> Previously (on RW), I asked about coatings, waterproofing plywood.
>>>>
>>>> Now, in an interior environment (moisture not an issue), I'm curious
>>>> about laminating an approx. 4' x 6' area of plywood with some other
>>>> thin-ish, or even not so thin-ish material -- from formica laminates,
>>>> to .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>>>>
>>>> I recall carpenters using gobs of white elmers glue for large-contact
>>>> wood areas, in building mezzanines in lofts, etc. Then there is
>>>> elmer's carpenter's/wood glue, mastics for tile (what's a mastic,
>>>> inyway??), epoxies, a zillion other adhesives.
>>>>
>>>> The general Q is: when to use what for what?
>>>>
>>>> For example, in the .030 SS/Alum I will place over 1/2" ply, I would
>>>> like to be able to just roll on some suitable adhesive over the full
>>>> 4x6 area, and press them together, proly via weight plates. What
>>>> would good choices be? How thick?
>>>>
>>>> Interestingly, an increase in thickness from ..5 to .532 will
>>>> generate about a 13% increase in stiffness, since stiffness is
>>>> proportional to the square of thickness...
>>>
>>> Proportional to the *cube* of thickness.
>>>
>>>> , but ONLY if there is no slippage between the two layers.
>>>
>>> Correct.
>>>
>>>> Thus, the requirement for full-surface bonding, via adhesive.
>>>>
>>>> Ackshooly, that 13% inc in stiffness presumes similar materials. I
>>>> measured that 1/4" alum plate is as stiff or stiffer than decent 1/2"
>>>> ply, so the increase in stiffness is likely to be a bit more than
>>>> 13%.
>>>
>>> Laminating materials with different Young's modulus is not generally
>>> additive.
>>
>> For 030 aluminum over 1/2" plywood the aluminum is going to carry most
>> of the tensile load from bending.....
>
> Yeah, as long as it's on the tension side....
>
>>..., which means that (a) the shear load at the
>> aluminum to plywood joint is going to be tremendous, and (b) the
>> assembly is going to be approximately as stiff as a 3/16" plate of
>> aluminum (because the cube root of 9/16 cubed minus 1/2 cubed is about
>> equal to 3/8).
>>
>> At least until the glue joint, or the underlying plywood, gives way.
>> Then it'll be a gawdaful mess.
>
> It doesn't sound like a good idea, does it? I wonder what kind of load
> EA is thinking about, that he's concerned about bending stiffness.

The plywood would keep the aluminum on the compression side from
buckling, for a while. Its kinda like an aluminum honeycomb between
solid sheet, with the plywood instead of the honeycomb.

If "light and stiff" are what he's looking for, it'd certainly deliver.
But when it let go it'd let go with a bang, and there's all sorts of
wrong with trying to bond wood to metal.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

On Tue, 12 Jul 2011 07:13:44 -0400, dadiOH wrote:

> Existential Angst wrote:
>> Awl --
>>
>> Previously (on RW), I asked about coatings, waterproofing plywood.
>>
>> Now, in an interior environment (moisture not an issue), I'm curious
>> about laminating an approx. 4' x 6' area of plywood with some other
>> thin-ish, or even not so thin-ish material -- from formica laminates,
>> to .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>>
>> I recall carpenters using gobs of white elmers glue for large-contact
>> wood areas, in building mezzanines in lofts, etc. Then there is elmer's
>> carpenter's/wood glue, mastics for tile (what's a mastic, inyway??),
>> epoxies, a zillion other adhesives.
>
> Mastic is a pasty material. Like linoleum paste...Liquid Nails...etc.
> __________________
>
>> The general Q is: when to use what for what?
>
> http://www.thistothat.com/
>
> For most of the things you mentioned, contact cement. _________________

Contact cement would, I think, work well for 030 aluminum to one side of
1/4 plywood, where the wood would have a chance to flex. It may work on
1/2" plywood if the bond isn't heavily stressed. But I think you'd
overcome the strength of the bond if you tried it on both sides, and then
loaded things heavily.

'course, a quick look at yield strengths of Al and contact cement, plus
some calculations, would tell you what's what.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

On Jul 12, 1:54=A0am, "Existential Angst" <[email protected]> wrote:

>
> >>>>> For example, in the .030 SS/Alum I will place over 1/2" ply, I woul=
d
> >>>>> like to be able to just roll on some suitable adhesive over the ful=
l
> >>>>> 4x6 area, and press them together, proly via weight plates. What
> >>>>> would good choices be? =A0How thick?
>

> Christ, idn't ANYTHING simple, anymore??? =A0 Sheeesh.....
> --
> EA

Without knowing what you are using the plywood and aluminum for it is
a little hard to provide good advise. But I suspect you could use
contact cement that is used to laminate formica on to particle board.
Be sure to clean the aluminum with sandpaper just before applying the
contact cement on the aluminum.

You put contact cement on both the aluminum and the plywood and let
dry until not tacky. Then cover the plywood with newspaper and then
put on the aluminum sheet. Get it aligned and then pull out the
newspaper and press on the aluminum sheet.

Dan

On Jul 12, 11:12=A0am, "Existential Angst" <[email protected]> wrote:

> So how do you resolve the disparate opinion from Tim and Robatoy, ito of
> symmetrical lamination?

I can't speak for Tim, but I have laminated elevator panels,
restaurant cabinets, bars, floors, walls, tables, countertops in a
variety of materials, back splashes, suspended ceiling sections,
valences.... I could go on.

The most stable 'packages' do not include MDF or plywood. When you
laminate onto plywood, your joint is only going to be as strong as
the next ply's adhesion to the ply below. You have no control over
that.
A quality particle board, and yes there are many, many grades
(hardwood, long fibre, different binders, densities etc.), when
laminated, will be a far better performer that a regular plywood,
again assuming properly laminated. In terms of strength, a proper
plywood (and there is a lot of shit out there) will be stronger, but
cost and the de-lamination problems which I have encountered over the
years doesn't make a plywood an automatic choice over PB. Proper High
Density PB is VERY impact resistant especially when clad in a GP grade
HPLAM.

I have used sprayed rubber contact cement for years and years and only
like the Imperial airless 32 lb cannisters, as the layer of adhesive
can be very thin and therefore not give you much slippage relative to
the laminate and substrate. Too much rubber contact cement and you
'disconnect' the laminate laterally from the base. It actually slides
ever so slightly even after it has cured. Wilsonart 3000 PVA does not
allow for slippage which can set up immense tension between the lam
and subs to the point that 0.125 acrylic with actually form hairline
cracks, so in that app, use rubber contact cement.

People I know are now using an MDF and/or PB which is water resistant,
but not as nutso-coo-coo as Extira waterproof... or expensive.

And ALWAYS ALWAYS use a balance sheet even IF you're going to screw
the 'half' package to a row of cabinets. For the little time and money
involved, it is simply silly NOT to. In two adjoining buildings, I
laminated the elevators panels in one building, my way, 15 years ago.
The other building's elevator (I didn't bid on that gig) has its
panels redone, at contractor's expense, after 2 years, THEN they did
use a balance sheet that time but cheaped out on post-form grade
laminate, thinking they'd save a few bucks. Within 6 months, they had
me do it that time. I billed them for materials only. The building's
owner added $ 500.00 for labour. (Not enough, mind you, but I got a
lot of referrals over the years from him.)

Shortcuts WILL bite you in the ass......like that time, I....nebber
mind...

"Existential Angst" <[email protected]> wrote in message
news:[email protected]...
> Awl --
>
> Previously (on RW), I asked about coatings, waterproofing plywood.
>
> Now, in an interior environment (moisture not an issue), I'm curious about
> laminating an approx. 4' x 6' area of plywood with some other thin-ish, or
> even not so thin-ish material -- from formica laminates, to .030 SS or
> Alum sheet, to 1/4" rubberized tile, linoleum.
>
> I recall carpenters using gobs of white elmers glue for large-contact wood
> areas, in building mezzanines in lofts, etc.
> Then there is elmer's carpenter's/wood glue, mastics for tile (what's a
> mastic, inyway??), epoxies, a zillion other adhesives.
>
> The general Q is: when to use what for what?
>
> For example, in the .030 SS/Alum I will place over 1/2" ply, I would like
> to be able to just roll on some suitable adhesive over the full 4x6 area,
> and press them together, proly via weight plates.
> What would good choices be? How thick?
>
> Interestingly, an increase in thickness from ..5 to .532 will generate
> about a 13% increase in stiffness, since stiffness is proportional to the
> square of thickness...

Proportional to the *cube* of thickness.

> , but ONLY if there is no slippage between the two layers.

Correct.

> Thus, the requirement for full-surface bonding, via adhesive.
>
> Ackshooly, that 13% inc in stiffness presumes similar materials. I
> measured that 1/4" alum plate is as stiff or stiffer than decent 1/2" ply,
> so the increase in stiffness is likely to be a bit more than 13%.

Laminating materials with different Young's modulus is not generally
additive.

>
> Inyway, I'd like an idea of how to gauge the type of adhesive to
> application. Bang fer the buck is always good, as well.

If you're laminating on the neutral axis, the situation is not demanding.
White glue works fine for two layers of softwood, of equal thickness. Shear
loads are low.

When the lamination occurs off the neutral axis you have bigger shear loads
on the glue line, and they can be quite high.

Aluminum is a bugger to bond to if you need high strength. Commercially,
they use PAA -- phosphoric acid anodizing -- and you actually bond to the
anodizing, not the aluminum. I've described the "scratch-in" method of
getting a good bond to epoxy several times here. That would work, but it's
not practical for a big surface. It's good for small things.

When I have a question like that I get on the phone with 3M, Loctite, or one
of the other big guys, and keep bugging them until I get to an engineer who
knows what he's talking about. Ask about self-etching adhesives and adhesive
primers for aluminum. I've heard of them, but I don't know of any specifics.

>
> Along these lines, I see all kinds of two-part epoxies, specialized for
> wood, metal, ceramics/glass, etc.
> Afaict, they all work the same on everything, with perhaps the exception
> of things like nylon, delrin, other "greasy" plastics. Any opinions on
> this?

There are a blue million epoxy formulations. The common one that would be
reasonable in your application is an ordinary room-temperature-cure (RTC),
phenol-cured epoxy. In other words, boatbuilding epoxy. You probably have a
West Marine Supply (not WEST System) somewhere near Yonkers. We have them in
NJ. They carry common brands.

Epoxy is anti-thixotropic. In other words, it drools, unless it's modified
for surfacing.

When you price it, you'll probably realize that you're better off buying
overlaid plywood in the first place. If you want to paint it, MDO
(medium-density-overlay) plywood is fairly cheap and very smooth. Any lumber
supply that serves custom cabinet builders should have it. Don't get it wet
or you'll be sorry.

There are many other overlays available, including at least two thickness of
melamine (Formica, etc.). If print-through of the grain is an issue, make
sure it's either a thick overlay (MDO is thick enough), that it's a hard
material (like melamine), or it has a hardwood top veneer under the overlay.
Now you're getting into more costly stuff.

Good luck.

--
Ed Huntress


> --
> EA
>
>

"Tim" <[email protected]> wrote in message
news:[email protected]...
> On Mon, 11 Jul 2011 23:23:50 -0400, Ed Huntress wrote:
>
>> "Existential Angst" <[email protected]> wrote in message
>> news:[email protected]...
>>> Awl --
>>>
>>> Previously (on RW), I asked about coatings, waterproofing plywood.
>>>
>>> Now, in an interior environment (moisture not an issue), I'm curious
>>> about laminating an approx. 4' x 6' area of plywood with some other
>>> thin-ish, or even not so thin-ish material -- from formica laminates,
>>> to .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>>>
>>> I recall carpenters using gobs of white elmers glue for large-contact
>>> wood areas, in building mezzanines in lofts, etc. Then there is elmer's
>>> carpenter's/wood glue, mastics for tile (what's a mastic, inyway??),
>>> epoxies, a zillion other adhesives.
>>>
>>> The general Q is: when to use what for what?
>>>
>>> For example, in the .030 SS/Alum I will place over 1/2" ply, I would
>>> like to be able to just roll on some suitable adhesive over the full
>>> 4x6 area, and press them together, proly via weight plates. What would
>>> good choices be? How thick?
>>>
>>> Interestingly, an increase in thickness from ..5 to .532 will generate
>>> about a 13% increase in stiffness, since stiffness is proportional to
>>> the square of thickness...
>>
>> Proportional to the *cube* of thickness.
>>
>>> , but ONLY if there is no slippage between the two layers.
>>
>> Correct.
>>
>>> Thus, the requirement for full-surface bonding, via adhesive.
>>>
>>> Ackshooly, that 13% inc in stiffness presumes similar materials. I
>>> measured that 1/4" alum plate is as stiff or stiffer than decent 1/2"
>>> ply, so the increase in stiffness is likely to be a bit more than 13%.
>>
>> Laminating materials with different Young's modulus is not generally
>> additive.
>
> For 030 aluminum over 1/2" plywood the aluminum is going to carry most of
> the tensile load from bending.....

Yeah, as long as it's on the tension side....

>..., which means that (a) the shear load at the
> aluminum to plywood joint is going to be tremendous, and (b) the assembly
> is going to be approximately as stiff as a 3/16" plate of aluminum
> (because the cube root of 9/16 cubed minus 1/2 cubed is about equal to
> 3/8).
>
> At least until the glue joint, or the underlying plywood, gives way.
> Then it'll be a gawdaful mess.

It doesn't sound like a good idea, does it? I wonder what kind of load EA is
thinking about, that he's concerned about bending stiffness.

--
Ed Huntress

>
> --
> Tim Wescott
> Control system and signal processing consulting
> www.wescottdesign.com

"Tim" <[email protected]> wrote in message
news:[email protected]...
> On Tue, 12 Jul 2011 01:06:07 -0400, Ed Huntress wrote:
>
>> "Tim" <[email protected]> wrote in message
>> news:[email protected]...
>>> On Mon, 11 Jul 2011 23:23:50 -0400, Ed Huntress wrote:
>>>
>>>> "Existential Angst" <[email protected]> wrote in message
>>>> news:[email protected]...
>>>>> Awl --
>>>>>
>>>>> Previously (on RW), I asked about coatings, waterproofing plywood.
>>>>>
>>>>> Now, in an interior environment (moisture not an issue), I'm curious
>>>>> about laminating an approx. 4' x 6' area of plywood with some other
>>>>> thin-ish, or even not so thin-ish material -- from formica laminates,
>>>>> to .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>>>>>
>>>>> I recall carpenters using gobs of white elmers glue for large-contact
>>>>> wood areas, in building mezzanines in lofts, etc. Then there is
>>>>> elmer's carpenter's/wood glue, mastics for tile (what's a mastic,
>>>>> inyway??), epoxies, a zillion other adhesives.
>>>>>
>>>>> The general Q is: when to use what for what?
>>>>>
>>>>> For example, in the .030 SS/Alum I will place over 1/2" ply, I would
>>>>> like to be able to just roll on some suitable adhesive over the full
>>>>> 4x6 area, and press them together, proly via weight plates. What
>>>>> would good choices be? How thick?
>>>>>
>>>>> Interestingly, an increase in thickness from ..5 to .532 will
>>>>> generate about a 13% increase in stiffness, since stiffness is
>>>>> proportional to the square of thickness...
>>>>
>>>> Proportional to the *cube* of thickness.
>>>>
>>>>> , but ONLY if there is no slippage between the two layers.
>>>>
>>>> Correct.
>>>>
>>>>> Thus, the requirement for full-surface bonding, via adhesive.
>>>>>
>>>>> Ackshooly, that 13% inc in stiffness presumes similar materials. I
>>>>> measured that 1/4" alum plate is as stiff or stiffer than decent 1/2"
>>>>> ply, so the increase in stiffness is likely to be a bit more than
>>>>> 13%.
>>>>
>>>> Laminating materials with different Young's modulus is not generally
>>>> additive.
>>>
>>> For 030 aluminum over 1/2" plywood the aluminum is going to carry most
>>> of the tensile load from bending.....
>>
>> Yeah, as long as it's on the tension side....
>>
>>>..., which means that (a) the shear load at the
>>> aluminum to plywood joint is going to be tremendous, and (b) the
>>> assembly is going to be approximately as stiff as a 3/16" plate of
>>> aluminum (because the cube root of 9/16 cubed minus 1/2 cubed is about
>>> equal to 3/8).
>>>
>>> At least until the glue joint, or the underlying plywood, gives way.
>>> Then it'll be a gawdaful mess.
>>
>> It doesn't sound like a good idea, does it? I wonder what kind of load
>> EA is thinking about, that he's concerned about bending stiffness.
>
> The plywood would keep the aluminum on the compression side from
> buckling, for a while. Its kinda like an aluminum honeycomb between
> solid sheet, with the plywood instead of the honeycomb.
>
> If "light and stiff" are what he's looking for, it'd certainly deliver.
> But when it let go it'd let go with a bang, and there's all sorts of
> wrong with trying to bond wood to metal.

Christ, idn't ANYTHING simple, anymore??? Sheeesh.....
--
EA




>
> --
> Tim Wescott
> Control system and signal processing consulting
> www.wescottdesign.com

"Jim Wilkins" <[email protected]> wrote in message
news:7b948d4f-6276-4307-94a4-4c57ec4bcbf9@gh5g2000vbb.googlegroups.com...
On Jul 12, 1:39 am, Tim <[email protected]> wrote:
> ...>
> If "light and stiff" are what he's looking for, it'd certainly deliver.
> But when it let go it'd let go with a bang, and there's all sorts of
> wrong with trying to bond wood to metal.
>
> --
> Tim Wescott

>The temperature coefficients of expansion, for one.
>
>jsw

That shouldn't be a big issue indoors. With wood, the big issue is expansion
and shrinkage from changes in humidity, even indoors, between seasons. If
you put an impermeable material on just one side, you're likely to have some
serious warping between seasons.

--
Ed Huntress

"dadiOH" <[email protected]> wrote in message
news:[email protected]...
> Existential Angst wrote:
>> Awl --
>>
>> Previously (on RW), I asked about coatings, waterproofing plywood.
>>
>> Now, in an interior environment (moisture not an issue), I'm curious
>> about laminating an approx. 4' x 6' area of plywood with some other
>> thin-ish, or even not so thin-ish material -- from formica laminates,
>> to .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>>
>> I recall carpenters using gobs of white elmers glue for large-contact
>> wood areas, in building mezzanines in lofts, etc.
>> Then there is elmer's carpenter's/wood glue, mastics for tile (what's
>> a mastic, inyway??), epoxies, a zillion other adhesives.
>
> Mastic is a pasty material. Like linoleum paste...Liquid Nails...etc.
> __________________
>
>> The general Q is: when to use what for what?
>
> http://www.thistothat.com/

Very inneresting site, lots of upside potential with that site, that I
emailed them about.


>
> For most of the things you mentioned, contact cement.

So it seems!!!
--
EA





> _________________
>
> --
>
> dadiOH
> ____________________________
>
> dadiOH's dandies v3.06...
> ...a help file of info about MP3s, recording from
> LP/cassette and tips & tricks on this and that.
> Get it at http://mysite.verizon.net/xico
>
>
>

"Robatoy" <[email protected]> wrote in message
news:[email protected]...
On Jul 11, 10:54 pm, "Existential Angst" <[email protected]> wrote:

> Any opinions on this?

Yes. Many opinions. Just make sure that when laminating dissimilar
materials, to do both sides of the substrate, a 'balance' sheet.
==========================================

A very inneresting idea, altho in this case it will likely add substantially
to costs.
But mebbe a workable compromise is to laminate both sides, but not with
identical materials.
Proly an ongoing experiment.
But I do hear the demands of symmetry.... :)



Trying to get away without one is foolish. In case of laminate, just a
cheap discontinued colour will suffice.
===========================================

In non-stress situations, like countertops, one-sided lamination seems OK,
but mebbe even there, two-sided lamination might help longevity (warping,
etc)..



Also, look into Wilsonart 3000 adhesive. Water based, will stick
anything to anything (other than greasy plastics).
Lots of open time and a decent roller which will allow your body
weight to do the work is all you need.
Wilsonart 3000 is NOT contact cement but works a bit like it. One side
of the joint has to have minimal porosity.
==============================================

Will look into Wilsonart.

What does "contact cement" connote, adhesive-wise? Is it a specific genre,
or are there a variety of types?
--
EA

"Tim" <[email protected]> wrote in message
news:[email protected]...
> On Tue, 12 Jul 2011 07:13:44 -0400, dadiOH wrote:
>
>> Existential Angst wrote:
>>> Awl --
>>>
>>> Previously (on RW), I asked about coatings, waterproofing plywood.
>>>
>>> Now, in an interior environment (moisture not an issue), I'm curious
>>> about laminating an approx. 4' x 6' area of plywood with some other
>>> thin-ish, or even not so thin-ish material -- from formica laminates,
>>> to .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>>>
>>> I recall carpenters using gobs of white elmers glue for large-contact
>>> wood areas, in building mezzanines in lofts, etc. Then there is elmer's
>>> carpenter's/wood glue, mastics for tile (what's a mastic, inyway??),
>>> epoxies, a zillion other adhesives.
>>
>> Mastic is a pasty material. Like linoleum paste...Liquid Nails...etc.
>> __________________
>>
>>> The general Q is: when to use what for what?
>>
>> http://www.thistothat.com/
>>
>> For most of the things you mentioned, contact cement. _________________
>
> Contact cement would, I think, work well for 030 aluminum to one side of
> 1/4 plywood, where the wood would have a chance to flex. It may work on
> 1/2" plywood if the bond isn't heavily stressed.

You're saying the bond would be less stressed with thinner ply than
thicker??
That seems counter-intuitive!


But I think you'd
> overcome the strength of the bond if you tried it on both sides, and then
> loaded things heavily.

Iow, you advise against Robatoy's advice of laminating both sides?
Reason?

>
> 'course, a quick look at yield strengths of Al and contact cement, plus
> some calculations, would tell you what's what.

4 ft x 6 ft is a lot of contact area. There will be some flex, but not like
bending anything into a U.
I'm thinking over a 4-6 ft dimension, occasional flex of mebbe an inch or
two.
--
EA





>
> --
> Tim Wescott
> Control system and signal processing consulting
> www.wescottdesign.com

"Existential Angst" <[email protected]> wrote in message
news:[email protected]...
> "Robatoy" <[email protected]> wrote in message
> news:[email protected]...
> On Jul 11, 10:54 pm, "Existential Angst" <[email protected]> wrote:
>
>> Any opinions on this?
>
> Yes. Many opinions. Just make sure that when laminating dissimilar
> materials, to do both sides of the substrate, a 'balance' sheet.
> ==========================================
>
> A very inneresting idea, altho in this case it will likely add
> substantially to costs.
> But mebbe a workable compromise is to laminate both sides, but not with
> identical materials.
> Proly an ongoing experiment.
> But I do hear the demands of symmetry.... :)
>
>
>
> Trying to get away without one is foolish. In case of laminate, just a
> cheap discontinued colour will suffice.
> ===========================================
>
> In non-stress situations, like countertops, one-sided lamination seems OK,
> but mebbe even there, two-sided lamination might help longevity (warping,
> etc)..
>
>
>
> Also, look into Wilsonart 3000 adhesive. Water based, will stick
> anything to anything (other than greasy plastics).
> Lots of open time and a decent roller which will allow your body
> weight to do the work is all you need.
> Wilsonart 3000 is NOT contact cement but works a bit like it. One side
> of the joint has to have minimal porosity.
> ==============================================
>
> Will look into Wilsonart.
>
> What does "contact cement" connote, adhesive-wise? Is it a specific
> genre, or are there a variety of types?
> --
> EA

There are a several types. They have great relative peel and cleavage
strength, but they yield a bit in shear. You want that with a countertop or
you'd have warping problems.

EA, you've asked a question that could go around in circles for a long time.
Why don't you just tell us what it is you're trying to accomplish? That will
narrow it down.

As for being complicated, back in '78 or '79 I wrote a 16-page Special
Report for _American Machinist_, titled "Adhesives in Metalworking," or
something like that. I took four months to research it and I travelled all
over the country, visiting engineering companies and suppliers who work at
the high-performance end of the business. My report had so many elements in
it, it was hard to keep it organized. And it just scratched the surface of
the subject.

You're right, it is a very complicated subject. If you've ever read the
reports on adhesives from the USDA Forest Products Laboratory, you know
they're long -- and excellent. And that's just for wood and wood composites.
When you get metal and plastics involved, the complexity compounds.

That is, if you need high performance. The gummy glues, like contact cement
and consumer-grade moisture-cure polyurethanes, solve a hundred different
problems very neatly. But that's because most applications only require one
or two types of strength -- in their case, it's mostly peel and cleavage,
which are the toughest kinds of strength to get, usually, when you're
bonding dissimilar materials. Contact cement is not a strong adhesive in
engineering terms. But it may well be the strongest, and the best, for your
application.

So tell us what the application is.

--
Ed Huntress

"Existential Angst" <[email protected]> wrote in message
news:[email protected]...
> "Tim" <[email protected]> wrote in message
> news:[email protected]...
>> On Tue, 12 Jul 2011 07:13:44 -0400, dadiOH wrote:
>>
>>> Existential Angst wrote:
>>>> Awl --
>>>>
>>>> Previously (on RW), I asked about coatings, waterproofing plywood.
>>>>
>>>> Now, in an interior environment (moisture not an issue), I'm curious
>>>> about laminating an approx. 4' x 6' area of plywood with some other
>>>> thin-ish, or even not so thin-ish material -- from formica laminates,
>>>> to .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>>>>
>>>> I recall carpenters using gobs of white elmers glue for large-contact
>>>> wood areas, in building mezzanines in lofts, etc. Then there is elmer's
>>>> carpenter's/wood glue, mastics for tile (what's a mastic, inyway??),
>>>> epoxies, a zillion other adhesives.
>>>
>>> Mastic is a pasty material. Like linoleum paste...Liquid Nails...etc.
>>> __________________
>>>
>>>> The general Q is: when to use what for what?
>>>
>>> http://www.thistothat.com/
>>>
>>> For most of the things you mentioned, contact cement. _________________
>>
>> Contact cement would, I think, work well for 030 aluminum to one side of
>> 1/4 plywood, where the wood would have a chance to flex. It may work on
>> 1/2" plywood if the bond isn't heavily stressed.
>
> You're saying the bond would be less stressed with thinner ply than
> thicker??
> That seems counter-intuitive!

Tim is right.



>
>
> But I think you'd
>> overcome the strength of the bond if you tried it on both sides, and then
>> loaded things heavily.
>
> Iow, you advise against Robatoy's advice of laminating both sides?
> Reason?
>
>>
>> 'course, a quick look at yield strengths of Al and contact cement, plus
>> some calculations, would tell you what's what.
>
> 4 ft x 6 ft is a lot of contact area. There will be some flex, but not
> like bending anything into a U.
> I'm thinking over a 4-6 ft dimension, occasional flex of mebbe an inch or
> two.
> --
> EA
>
>
>
>
>
>>
>> --
>> Tim Wescott
>> Control system and signal processing consulting
>> www.wescottdesign.com
>
>

"Ed Huntress" <[email protected]> wrote in message
news:[email protected]...
>
> "Existential Angst" <[email protected]> wrote in message
> news:[email protected]...
>> Awl --
>>
>> Previously (on RW), I asked about coatings, waterproofing plywood.
>>
>> Now, in an interior environment (moisture not an issue), I'm curious
>> about laminating an approx. 4' x 6' area of plywood with some other
>> thin-ish, or even not so thin-ish material -- from formica laminates, to
>> .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>>
>> I recall carpenters using gobs of white elmers glue for large-contact
>> wood areas, in building mezzanines in lofts, etc.
>> Then there is elmer's carpenter's/wood glue, mastics for tile (what's a
>> mastic, inyway??), epoxies, a zillion other adhesives.
>>
>> The general Q is: when to use what for what?
>>
>> For example, in the .030 SS/Alum I will place over 1/2" ply, I would like
>> to be able to just roll on some suitable adhesive over the full 4x6 area,
>> and press them together, proly via weight plates.
>> What would good choices be? How thick?
>>
>> Interestingly, an increase in thickness from ..5 to .532 will generate
>> about a 13% increase in stiffness, since stiffness is proportional to the
>> square of thickness...
>
> Proportional to the *cube* of thickness.

Dayum....... :)


>
>> , but ONLY if there is no slippage between the two layers.
>
> Correct.
>
>> Thus, the requirement for full-surface bonding, via adhesive.
>>
>> Ackshooly, that 13% inc in stiffness presumes similar materials. I
>> measured that 1/4" alum plate is as stiff or stiffer than decent 1/2"
>> ply, so the increase in stiffness is likely to be a bit more than 13%.
>
> Laminating materials with different Young's modulus is not generally
> additive.
>
>>
>> Inyway, I'd like an idea of how to gauge the type of adhesive to
>> application. Bang fer the buck is always good, as well.
>
> If you're laminating on the neutral axis, the situation is not demanding.
> White glue works fine for two layers of softwood, of equal thickness.
> Shear loads are low.
>
> When the lamination occurs off the neutral axis you have bigger shear
> loads on the glue line, and they can be quite high.
>
> Aluminum is a bugger to bond to if you need high strength. Commercially,
> they use PAA -- phosphoric acid anodizing -- and you actually bond to the
> anodizing, not the aluminum. I've described the "scratch-in" method of
> getting a good bond to epoxy several times here. That would work, but it's
> not practical for a big surface. It's good for small things.
>
> When I have a question like that I get on the phone with 3M, Loctite, or
> one of the other big guys, and keep bugging them until I get to an
> engineer who knows what he's talking about. Ask about self-etching
> adhesives and adhesive primers for aluminum. I've heard of them, but I
> don't know of any specifics.
>
>>
>> Along these lines, I see all kinds of two-part epoxies, specialized for
>> wood, metal, ceramics/glass, etc.
>> Afaict, they all work the same on everything, with perhaps the exception
>> of things like nylon, delrin, other "greasy" plastics. Any opinions on
>> this?
>
> There are a blue million epoxy formulations. The common one that would be
> reasonable in your application is an ordinary room-temperature-cure (RTC),
> phenol-cured epoxy. In other words, boatbuilding epoxy. You probably have
> a West Marine Supply (not WEST System) somewhere near Yonkers. We have
> them in NJ. They carry common brands.
>
> Epoxy is anti-thixotropic. In other words, it drools, unless it's modified
> for surfacing.
>
> When you price it, you'll probably realize that you're better off buying
> overlaid plywood in the first place. If you want to paint it, MDO
> (medium-density-overlay) plywood is fairly cheap and very smooth. Any
> lumber supply that serves custom cabinet builders should have it. Don't
> get it wet or you'll be sorry.
>
> There are many other overlays available, including at least two thickness
> of melamine (Formica, etc.). If print-through of the grain is an issue,
> make sure it's either a thick overlay (MDO is thick enough), that it's a
> hard material (like melamine), or it has a hardwood top veneer under the
> overlay. Now you're getting into more costly stuff.
>
> Good luck.

It appears ahm gonna need it!!
Unless some of the simple solutions turn out.
Also, effing .030 alum is not cheap!! 1/8" would cost on the order of $150,
while 1/32" costs $75!!!!!
Talk about non-linear pricing -- holy shit.....

.030 SS is of course worse: $150 for the piece, altho I didn't compare this
to 1/8". I suspect about as non-linear.
Heh, and the 1/2" ply costs.... $20???? LOL

Appreciate the overview.

Oh, I asked elsewhere, but what does "contact cement" specifically connote?
Is it a genre, like "two-part epoxy" or white glues? A few people have
recommended it. Just wondering if I should be looking at a specific type.
--
EA


>
> --
> Ed Huntress
>
>
>> --
>> EA
>>
>>
>
>

"Ed Huntress" <[email protected]> wrote in message
news:[email protected]...
>
> "Existential Angst" <[email protected]> wrote in message
> news:[email protected]...
>> "Tim" <[email protected]> wrote in message
>> news:[email protected]...
>>> On Tue, 12 Jul 2011 07:13:44 -0400, dadiOH wrote:
>>>
>>>> Existential Angst wrote:
>>>>> Awl --
>>>>>
>>>>> Previously (on RW), I asked about coatings, waterproofing plywood.
>>>>>
>>>>> Now, in an interior environment (moisture not an issue), I'm curious
>>>>> about laminating an approx. 4' x 6' area of plywood with some other
>>>>> thin-ish, or even not so thin-ish material -- from formica laminates,
>>>>> to .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>>>>>
>>>>> I recall carpenters using gobs of white elmers glue for large-contact
>>>>> wood areas, in building mezzanines in lofts, etc. Then there is
>>>>> elmer's
>>>>> carpenter's/wood glue, mastics for tile (what's a mastic, inyway??),
>>>>> epoxies, a zillion other adhesives.
>>>>
>>>> Mastic is a pasty material. Like linoleum paste...Liquid Nails...etc.
>>>> __________________
>>>>
>>>>> The general Q is: when to use what for what?
>>>>
>>>> http://www.thistothat.com/
>>>>
>>>> For most of the things you mentioned, contact cement. _________________
>>>
>>> Contact cement would, I think, work well for 030 aluminum to one side of
>>> 1/4 plywood, where the wood would have a chance to flex. It may work on
>>> 1/2" plywood if the bond isn't heavily stressed.
>>
>> You're saying the bond would be less stressed with thinner ply than
>> thicker??
>> That seems counter-intuitive!
>
> Tim is right.

Because there's less distance to the neutral axis?
If I'm right, do I get a prize??
--
EA


>
>
>
>>
>>
>> But I think you'd
>>> overcome the strength of the bond if you tried it on both sides, and
>>> then
>>> loaded things heavily.
>>
>> Iow, you advise against Robatoy's advice of laminating both sides?
>> Reason?
>>
>>>
>>> 'course, a quick look at yield strengths of Al and contact cement, plus
>>> some calculations, would tell you what's what.
>>
>> 4 ft x 6 ft is a lot of contact area. There will be some flex, but not
>> like bending anything into a U.
>> I'm thinking over a 4-6 ft dimension, occasional flex of mebbe an inch or
>> two.
>> --
>> EA
>>
>>
>>
>>
>>
>>>
>>> --
>>> Tim Wescott
>>> Control system and signal processing consulting
>>> www.wescottdesign.com
>>
>>
>
>

"Ed Huntress" <[email protected]> wrote in message
news:[email protected]...
>
> "Existential Angst" <[email protected]> wrote in message
> news:[email protected]...
>> "Robatoy" <[email protected]> wrote in message
>> news:[email protected]...
>> On Jul 11, 10:54 pm, "Existential Angst" <[email protected]> wrote:
>>
>>> Any opinions on this?
>>
>> Yes. Many opinions. Just make sure that when laminating dissimilar
>> materials, to do both sides of the substrate, a 'balance' sheet.
>> ==========================================
>>
>> A very inneresting idea, altho in this case it will likely add
>> substantially to costs.
>> But mebbe a workable compromise is to laminate both sides, but not with
>> identical materials.
>> Proly an ongoing experiment.
>> But I do hear the demands of symmetry.... :)
>>
>>
>>
>> Trying to get away without one is foolish. In case of laminate, just a
>> cheap discontinued colour will suffice.
>> ===========================================
>>
>> In non-stress situations, like countertops, one-sided lamination seems
>> OK, but mebbe even there, two-sided lamination might help longevity
>> (warping, etc)..
>>
>>
>>
>> Also, look into Wilsonart 3000 adhesive. Water based, will stick
>> anything to anything (other than greasy plastics).
>> Lots of open time and a decent roller which will allow your body
>> weight to do the work is all you need.
>> Wilsonart 3000 is NOT contact cement but works a bit like it. One side
>> of the joint has to have minimal porosity.
>> ==============================================
>>
>> Will look into Wilsonart.
>>
>> What does "contact cement" connote, adhesive-wise? Is it a specific
>> genre, or are there a variety of types?
>> --
>> EA
>
> There are a several types. They have great relative peel and cleavage
> strength, but they yield a bit in shear. You want that with a countertop
> or you'd have warping problems.
>
> EA, you've asked a question that could go around in circles for a long
> time. Why don't you just tell us what it is you're trying to accomplish?
> That will narrow it down.
>
> As for being complicated, back in '78 or '79 I wrote a 16-page Special
> Report for _American Machinist_, titled "Adhesives in Metalworking," or
> something like that. I took four months to research it and I travelled all
> over the country, visiting engineering companies and suppliers who work at
> the high-performance end of the business. My report had so many elements
> in it, it was hard to keep it organized. And it just scratched the surface
> of the subject.

There is no end of complexity in chemistry. I worked with a guy whose
specialty was a single effing orbital of the copper atom under specific
energy conditions..... goodgawd......

>
> You're right, it is a very complicated subject. If you've ever read the
> reports on adhesives from the USDA Forest Products Laboratory, you know
> they're long -- and excellent. And that's just for wood and wood
> composites. When you get metal and plastics involved, the complexity
> compounds.
>
> That is, if you need high performance. The gummy glues, like contact
> cement and consumer-grade moisture-cure polyurethanes, solve a hundred
> different problems very neatly. But that's because most applications only
> require one or two types of strength -- in their case, it's mostly peel
> and cleavage, which are the toughest kinds of strength to get, usually,
> when you're bonding dissimilar materials. Contact cement is not a strong
> adhesive in engineering terms. But it may well be the strongest, and the
> best, for your application.
>
> So tell us what the application is.

Well, I can't spill ALL the beans..... :) :)

But basically it is a semi-portable jungle-jim-type apparatus, that needs to
be stabilized by a base, as the user will be pushing/pulling on the
apparatus, and the user's bodyweight is often what will prevent tipping.
True, I could make the apparatus itself 1,000# or so, and then I wouldn't
need a base..... LOL

The base has "guy poles" and gussets to the apparatus itself, so in
actuality, the base can be surprisingly thin and function pretty well, but
of course not too thin. I was frankly quite surprised that the 1/2 ply
works so well.

So there is some flex in the base, on the order of a cupla inches over a 4
ft to 6 ft dimension, but nothing like a foot.

My laminating jihad here is in lieu of having to finish the ply. Ordinary
ply (one "good" face), with boucou coats of poly, actually turns out VERY
nicely, but goddamm, what a pita!! -- and ultimately proly perty costly ito
production. I'm looking for more of a slam/dunk solution, as well as some
alternative solutions ito style, interior design, etc.

So dats the overall context. I have some neat solutions for capping the
edges, etc, which is another story, but which also lends to the rigidity.
Heh, I could also get away with no adhesive at all, because of how the
edging is finished, and, if shear is really such a big deal (and would
destroy the ply over time in the flexing process), then mebbe the solution
is to omit the adhesive and just live without the additional stiffness of
unitized members.

We'll see what happens. Heh, you want a unit??
It's basically the portable version of the stuff I've been building, that I
offered you once before -- which you graciously declined..... :) :)
Oh, and for YOU, FREE INSTALLATION!!!!

So how do you resolve the disparate opinion from Tim and Robatoy, ito of
symmetrical lamination?
--
EA




>
> --
> Ed Huntress
>

"Existential Angst" <[email protected]> wrote in message
news:[email protected]...
> "Ed Huntress" <[email protected]> wrote in message
> news:[email protected]...
>>
>> "Existential Angst" <[email protected]> wrote in message
>> news:[email protected]...
>>> Awl --
>>>
>>> Previously (on RW), I asked about coatings, waterproofing plywood.
>>>
>>> Now, in an interior environment (moisture not an issue), I'm curious
>>> about laminating an approx. 4' x 6' area of plywood with some other
>>> thin-ish, or even not so thin-ish material -- from formica laminates, to
>>> .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>>>
>>> I recall carpenters using gobs of white elmers glue for large-contact
>>> wood areas, in building mezzanines in lofts, etc.
>>> Then there is elmer's carpenter's/wood glue, mastics for tile (what's a
>>> mastic, inyway??), epoxies, a zillion other adhesives.
>>>
>>> The general Q is: when to use what for what?
>>>
>>> For example, in the .030 SS/Alum I will place over 1/2" ply, I would
>>> like to be able to just roll on some suitable adhesive over the full 4x6
>>> area, and press them together, proly via weight plates.
>>> What would good choices be? How thick?
>>>
>>> Interestingly, an increase in thickness from ..5 to .532 will generate
>>> about a 13% increase in stiffness, since stiffness is proportional to
>>> the square of thickness...
>>
>> Proportional to the *cube* of thickness.
>
> Dayum....... :)
>
>
>>
>>> , but ONLY if there is no slippage between the two layers.
>>
>> Correct.
>>
>>> Thus, the requirement for full-surface bonding, via adhesive.
>>>
>>> Ackshooly, that 13% inc in stiffness presumes similar materials. I
>>> measured that 1/4" alum plate is as stiff or stiffer than decent 1/2"
>>> ply, so the increase in stiffness is likely to be a bit more than 13%.
>>
>> Laminating materials with different Young's modulus is not generally
>> additive.
>>
>>>
>>> Inyway, I'd like an idea of how to gauge the type of adhesive to
>>> application. Bang fer the buck is always good, as well.
>>
>> If you're laminating on the neutral axis, the situation is not demanding.
>> White glue works fine for two layers of softwood, of equal thickness.
>> Shear loads are low.
>>
>> When the lamination occurs off the neutral axis you have bigger shear
>> loads on the glue line, and they can be quite high.
>>
>> Aluminum is a bugger to bond to if you need high strength. Commercially,
>> they use PAA -- phosphoric acid anodizing -- and you actually bond to the
>> anodizing, not the aluminum. I've described the "scratch-in" method of
>> getting a good bond to epoxy several times here. That would work, but
>> it's not practical for a big surface. It's good for small things.
>>
>> When I have a question like that I get on the phone with 3M, Loctite, or
>> one of the other big guys, and keep bugging them until I get to an
>> engineer who knows what he's talking about. Ask about self-etching
>> adhesives and adhesive primers for aluminum. I've heard of them, but I
>> don't know of any specifics.
>>
>>>
>>> Along these lines, I see all kinds of two-part epoxies, specialized for
>>> wood, metal, ceramics/glass, etc.
>>> Afaict, they all work the same on everything, with perhaps the exception
>>> of things like nylon, delrin, other "greasy" plastics. Any opinions on
>>> this?
>>
>> There are a blue million epoxy formulations. The common one that would be
>> reasonable in your application is an ordinary room-temperature-cure
>> (RTC), phenol-cured epoxy. In other words, boatbuilding epoxy. You
>> probably have a West Marine Supply (not WEST System) somewhere near
>> Yonkers. We have them in NJ. They carry common brands.
>>
>> Epoxy is anti-thixotropic. In other words, it drools, unless it's
>> modified for surfacing.
>>
>> When you price it, you'll probably realize that you're better off buying
>> overlaid plywood in the first place. If you want to paint it, MDO
>> (medium-density-overlay) plywood is fairly cheap and very smooth. Any
>> lumber supply that serves custom cabinet builders should have it. Don't
>> get it wet or you'll be sorry.
>>
>> There are many other overlays available, including at least two thickness
>> of melamine (Formica, etc.). If print-through of the grain is an issue,
>> make sure it's either a thick overlay (MDO is thick enough), that it's a
>> hard material (like melamine), or it has a hardwood top veneer under the
>> overlay. Now you're getting into more costly stuff.
>>
>> Good luck.
>
> It appears ahm gonna need it!!
> Unless some of the simple solutions turn out.
> Also, effing .030 alum is not cheap!! 1/8" would cost on the order of
> $150, while 1/32" costs $75!!!!!
> Talk about non-linear pricing -- holy shit.....
>
> .030 SS is of course worse: $150 for the piece, altho I didn't compare
> this to 1/8". I suspect about as non-linear.
> Heh, and the 1/2" ply costs.... $20???? LOL
>
> Appreciate the overview.
>
> Oh, I asked elsewhere, but what does "contact cement" specifically
> connote?

Rubber-based. Usually Neoprene family. Solvent-type can be a wide variety of
Neoprene-type rubbers. Water-based typically is polychloroproprene. Don't
ask me what the hell that is, except that it's related to Neoprene.

> Is it a genre, like "two-part epoxy" or white glues?

It refers to glues that you usually apply to both surfaces, wait a bit, and
then press them together. You'll need a slip sheet of slick drafting paper
or something similar. Brown kraft paper will work. If you haven't done it,
look it up on YouTube and save yourself some grief.

The adhesive is somewhat air-impeded, like laminating polyester resin, so
the surface of each side is ready to stick when most of the solvent
evaporates.

But it's rubber, in the end.

> A few people have recommended it. Just wondering if I should be looking
> at a specific type.

Solvent-based usually is stronger, but don't count on that anymore. 3M
supplies some data on their formulations.

If you're counting on that bonded stiffness, and the panel stiffness that
results from making the structure thicker, that you were talking about
earlier, you won't get a lot of it with contact cement. But I think you're
chasing your tail on that issue, anyway. Again, it's a question of what your
application is.

--
Ed Huntress


> --
> EA

"Existential Angst" <[email protected]> wrote in message
news:[email protected]...
> "Ed Huntress" <[email protected]> wrote in message
> news:[email protected]...
>>
>> "Existential Angst" <[email protected]> wrote in message
>> news:[email protected]...
>>> "Tim" <[email protected]> wrote in message
>>> news:[email protected]...
>>>> On Tue, 12 Jul 2011 07:13:44 -0400, dadiOH wrote:
>>>>
>>>>> Existential Angst wrote:
>>>>>> Awl --
>>>>>>
>>>>>> Previously (on RW), I asked about coatings, waterproofing plywood.
>>>>>>
>>>>>> Now, in an interior environment (moisture not an issue), I'm curious
>>>>>> about laminating an approx. 4' x 6' area of plywood with some other
>>>>>> thin-ish, or even not so thin-ish material -- from formica laminates,
>>>>>> to .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>>>>>>
>>>>>> I recall carpenters using gobs of white elmers glue for large-contact
>>>>>> wood areas, in building mezzanines in lofts, etc. Then there is
>>>>>> elmer's
>>>>>> carpenter's/wood glue, mastics for tile (what's a mastic, inyway??),
>>>>>> epoxies, a zillion other adhesives.
>>>>>
>>>>> Mastic is a pasty material. Like linoleum paste...Liquid Nails...etc.
>>>>> __________________
>>>>>
>>>>>> The general Q is: when to use what for what?
>>>>>
>>>>> http://www.thistothat.com/
>>>>>
>>>>> For most of the things you mentioned, contact cement.
>>>>> _________________
>>>>
>>>> Contact cement would, I think, work well for 030 aluminum to one side
>>>> of
>>>> 1/4 plywood, where the wood would have a chance to flex. It may work
>>>> on
>>>> 1/2" plywood if the bond isn't heavily stressed.
>>>
>>> You're saying the bond would be less stressed with thinner ply than
>>> thicker??
>>> That seems counter-intuitive!
>>
>> Tim is right.
>
> Because there's less distance to the neutral axis?

No, because the force is a product of the volume of the material that's
trying to stretch or shrink, and thicker material exerts more force.

> If I'm right, do I get a prize??

When you're right, we'll consider it. d8-)

--
Ed Huntress


> --
> EA
>
>
>>
>>
>>
>>>
>>>
>>> But I think you'd
>>>> overcome the strength of the bond if you tried it on both sides, and
>>>> then
>>>> loaded things heavily.
>>>
>>> Iow, you advise against Robatoy's advice of laminating both sides?
>>> Reason?
>>>
>>>>
>>>> 'course, a quick look at yield strengths of Al and contact cement, plus
>>>> some calculations, would tell you what's what.
>>>
>>> 4 ft x 6 ft is a lot of contact area. There will be some flex, but not
>>> like bending anything into a U.
>>> I'm thinking over a 4-6 ft dimension, occasional flex of mebbe an inch
>>> or two.
>>> --
>>> EA
>>>
>>>
>>>
>>>
>>>
>>>>
>>>> --
>>>> Tim Wescott
>>>> Control system and signal processing consulting
>>>> www.wescottdesign.com
>>>
>>>
>>
>>
>
>

"Ed Huntress" <[email protected]> wrote in message
news:[email protected]...
>
> "Existential Angst" <[email protected]> wrote in message
> news:[email protected]...
>> "Ed Huntress" <[email protected]> wrote in message
>> news:[email protected]...
>>>
>>> "Existential Angst" <[email protected]> wrote in message
>>> news:[email protected]...
>>>> "Tim" <[email protected]> wrote in message
>>>> news:[email protected]...
>>>>> On Tue, 12 Jul 2011 07:13:44 -0400, dadiOH wrote:
>>>>>
>>>>>> Existential Angst wrote:
>>>>>>> Awl --
>>>>>>>
>>>>>>> Previously (on RW), I asked about coatings, waterproofing plywood.
>>>>>>>
>>>>>>> Now, in an interior environment (moisture not an issue), I'm curious
>>>>>>> about laminating an approx. 4' x 6' area of plywood with some other
>>>>>>> thin-ish, or even not so thin-ish material -- from formica
>>>>>>> laminates,
>>>>>>> to .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>>>>>>>
>>>>>>> I recall carpenters using gobs of white elmers glue for
>>>>>>> large-contact
>>>>>>> wood areas, in building mezzanines in lofts, etc. Then there is
>>>>>>> elmer's
>>>>>>> carpenter's/wood glue, mastics for tile (what's a mastic, inyway??),
>>>>>>> epoxies, a zillion other adhesives.
>>>>>>
>>>>>> Mastic is a pasty material. Like linoleum paste...Liquid
>>>>>> Nails...etc.
>>>>>> __________________
>>>>>>
>>>>>>> The general Q is: when to use what for what?
>>>>>>
>>>>>> http://www.thistothat.com/
>>>>>>
>>>>>> For most of the things you mentioned, contact cement.
>>>>>> _________________
>>>>>
>>>>> Contact cement would, I think, work well for 030 aluminum to one side
>>>>> of
>>>>> 1/4 plywood, where the wood would have a chance to flex. It may work
>>>>> on
>>>>> 1/2" plywood if the bond isn't heavily stressed.
>>>>
>>>> You're saying the bond would be less stressed with thinner ply than
>>>> thicker??
>>>> That seems counter-intuitive!
>>>
>>> Tim is right.
>>
>> Because there's less distance to the neutral axis?
>
> No, because the force is a product of the volume of the material that's
> trying to stretch or shrink, and thicker material exerts more force.

Well, in the case of pure flex, won't a thicker material flex less, thereby
introducing less force?
Seems like an optimization problem here.....
Also, by definition, distance from the neutral axis would have SOME
contribution, no?

>
>> If I'm right, do I get a prize??
>
> When you're right, we'll consider it. d8-)

Will I get to specify her dimensions?
--
EA


>
> --
> Ed Huntress
>
>
>> --
>> EA
>>
>>
>>>
>>>
>>>
>>>>
>>>>
>>>> But I think you'd
>>>>> overcome the strength of the bond if you tried it on both sides, and
>>>>> then
>>>>> loaded things heavily.
>>>>
>>>> Iow, you advise against Robatoy's advice of laminating both sides?
>>>> Reason?
>>>>
>>>>>
>>>>> 'course, a quick look at yield strengths of Al and contact cement,
>>>>> plus
>>>>> some calculations, would tell you what's what.
>>>>
>>>> 4 ft x 6 ft is a lot of contact area. There will be some flex, but not
>>>> like bending anything into a U.
>>>> I'm thinking over a 4-6 ft dimension, occasional flex of mebbe an inch
>>>> or two.
>>>> --
>>>> EA
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>>
>>>>> --
>>>>> Tim Wescott
>>>>> Control system and signal processing consulting
>>>>> www.wescottdesign.com
>>>>
>>>>
>>>
>>>
>>
>>
>
>

"Existential Angst" <[email protected]> wrote in message
news:[email protected]...
> "Ed Huntress" <[email protected]> wrote in message
> news:[email protected]...
>>
>> "Existential Angst" <[email protected]> wrote in message
>> news:[email protected]...
>>> "Robatoy" <[email protected]> wrote in message
>>> news:[email protected]...
>>> On Jul 11, 10:54 pm, "Existential Angst" <[email protected]> wrote:
>>>
>>>> Any opinions on this?
>>>
>>> Yes. Many opinions. Just make sure that when laminating dissimilar
>>> materials, to do both sides of the substrate, a 'balance' sheet.
>>> ==========================================
>>>
>>> A very inneresting idea, altho in this case it will likely add
>>> substantially to costs.
>>> But mebbe a workable compromise is to laminate both sides, but not with
>>> identical materials.
>>> Proly an ongoing experiment.
>>> But I do hear the demands of symmetry.... :)
>>>
>>>
>>>
>>> Trying to get away without one is foolish. In case of laminate, just a
>>> cheap discontinued colour will suffice.
>>> ===========================================
>>>
>>> In non-stress situations, like countertops, one-sided lamination seems
>>> OK, but mebbe even there, two-sided lamination might help longevity
>>> (warping, etc)..
>>>
>>>
>>>
>>> Also, look into Wilsonart 3000 adhesive. Water based, will stick
>>> anything to anything (other than greasy plastics).
>>> Lots of open time and a decent roller which will allow your body
>>> weight to do the work is all you need.
>>> Wilsonart 3000 is NOT contact cement but works a bit like it. One side
>>> of the joint has to have minimal porosity.
>>> ==============================================
>>>
>>> Will look into Wilsonart.
>>>
>>> What does "contact cement" connote, adhesive-wise? Is it a specific
>>> genre, or are there a variety of types?
>>> --
>>> EA
>>
>> There are a several types. They have great relative peel and cleavage
>> strength, but they yield a bit in shear. You want that with a countertop
>> or you'd have warping problems.
>>
>> EA, you've asked a question that could go around in circles for a long
>> time. Why don't you just tell us what it is you're trying to accomplish?
>> That will narrow it down.
>>
>> As for being complicated, back in '78 or '79 I wrote a 16-page Special
>> Report for _American Machinist_, titled "Adhesives in Metalworking," or
>> something like that. I took four months to research it and I travelled
>> all over the country, visiting engineering companies and suppliers who
>> work at the high-performance end of the business. My report had so many
>> elements in it, it was hard to keep it organized. And it just scratched
>> the surface of the subject.
>
> There is no end of complexity in chemistry. I worked with a guy whose
> specialty was a single effing orbital of the copper atom under specific
> energy conditions..... goodgawd......
>
>>
>> You're right, it is a very complicated subject. If you've ever read the
>> reports on adhesives from the USDA Forest Products Laboratory, you know
>> they're long -- and excellent. And that's just for wood and wood
>> composites. When you get metal and plastics involved, the complexity
>> compounds.
>>
>> That is, if you need high performance. The gummy glues, like contact
>> cement and consumer-grade moisture-cure polyurethanes, solve a hundred
>> different problems very neatly. But that's because most applications only
>> require one or two types of strength -- in their case, it's mostly peel
>> and cleavage, which are the toughest kinds of strength to get, usually,
>> when you're bonding dissimilar materials. Contact cement is not a strong
>> adhesive in engineering terms. But it may well be the strongest, and the
>> best, for your application.
>>
>> So tell us what the application is.
>
> Well, I can't spill ALL the beans..... :) :)
>
> But basically it is a semi-portable jungle-jim-type apparatus, that needs
> to be stabilized by a base, as the user will be pushing/pulling on the
> apparatus, and the user's bodyweight is often what will prevent tipping.
> True, I could make the apparatus itself 1,000# or so, and then I wouldn't
> need a base..... LOL
>
> The base has "guy poles" and gussets to the apparatus itself, so in
> actuality, the base can be surprisingly thin and function pretty well, but
> of course not too thin. I was frankly quite surprised that the 1/2 ply
> works so well.
>
> So there is some flex in the base, on the order of a cupla inches over a 4
> ft to 6 ft dimension, but nothing like a foot.
>
> My laminating jihad here is in lieu of having to finish the ply. Ordinary
> ply (one "good" face), with boucou coats of poly, actually turns out VERY
> nicely, but goddamm, what a pita!! -- and ultimately proly perty costly
> ito production. I'm looking for more of a slam/dunk solution, as well as
> some alternative solutions ito style, interior design, etc.
>
> So dats the overall context. I have some neat solutions for capping the
> edges, etc, which is another story, but which also lends to the rigidity.
> Heh, I could also get away with no adhesive at all, because of how the
> edging is finished, and, if shear is really such a big deal (and would
> destroy the ply over time in the flexing process), then mebbe the solution
> is to omit the adhesive and just live without the additional stiffness of
> unitized members.

Ok, the answer is clear. You want a pre-finished, overlaid plywood. You will
kick yourself if you find the right material *after* you've screwed around
trying to laminate it yourself. It will be cheaper in the long run, and
maybe in the short run.

Start Googling for overlaid plywood. There are many types.

Without getting into the engineering too much, consider this: You know that
the stiffness (and strength) increases with the cube of the thickness. So a
small increase in the ply thickness will be as good as a thinner, fancy,
two-sided laminate. As for one side versus two, the reasons for two sides
are to minimize warping and to get MUCH more strength from the compression
strength of the side that's in compression. Plywood's compression strength
ain't all that great. But if you aren't loading it too hard (you aren't),
compression stength should not come into play. One-sided should do it.
Warping probably will not be a problem.

BUT....and this is a big butt....the stiffness/weight ratio of plywood is
HIGHER than medium-grade foam-core fiberglass laminate. No kidding. You need
a fancy laminate, with high-density foam and Kevlar/carbon to produce better
stiffness/weight than ply. That's why racing dinghies (noteably
International 14s) are stiffer when made of cold-molded plywood than when
made of fiberglass. (And they last much longer, too, but that's another
story).

So go for ply, and any benefits you get from a pre-overlaid surface will be
cosmetic. That's all you need. If you want more stiffness, go for thicker
ply. If you're buying inch-graded ply and you want just a little more, get
some metric stuff.

As for the overlay, it depends on how much dent and ding resistance you
need. Resin-coated paper looks nice and takes paint well but it dents
easily. MDO is slick as a baby's butt but it, too, dings easily. The thin
melamine surfaces also ding easily, but they're cheap and they look nice
until you stick something hard into them. The thin melamine is great, too,
on MDF and particle board, but the first isn't very strong and the latter is
heavy as sin. Plywood is much stronger and lighter. Thick melamine overlay
can be expensive but it's nice.

You'll be much happier with overlay, I'm sure. Just look around to find the
right one.

>
> We'll see what happens. Heh, you want a unit??
> It's basically the portable version of the stuff I've been building, that
> I offered you once before -- which you graciously declined..... :) :)
> Oh, and for YOU, FREE INSTALLATION!!!!

I'd love one. But if you saw how small my house is, and how my shop is
already sort of multi-tiered, you'd realize why I graciously decline.

Besides, what I need is not a gym. It's joint and tendon therapy. d8-)

>
> So how do you resolve the disparate opinion from Tim and Robatoy, ito of
> symmetrical lamination?

See above. There is more to it, but we're not engineering aircraft wings or
racing boats.

--
Ed Huntress


> --
> EA

"Existential Angst" <[email protected]> wrote in message
news:[email protected]...
> "Ed Huntress" <[email protected]> wrote in message
> news:[email protected]...
>>
>> "Existential Angst" <[email protected]> wrote in message
>> news:[email protected]...
>>> "Ed Huntress" <[email protected]> wrote in message
>>> news:[email protected]...
>>>>
>>>> "Existential Angst" <[email protected]> wrote in message
>>>> news:[email protected]...
>>>>> "Tim" <[email protected]> wrote in message
>>>>> news:[email protected]...
>>>>>> On Tue, 12 Jul 2011 07:13:44 -0400, dadiOH wrote:
>>>>>>
>>>>>>> Existential Angst wrote:
>>>>>>>> Awl --
>>>>>>>>
>>>>>>>> Previously (on RW), I asked about coatings, waterproofing plywood.
>>>>>>>>
>>>>>>>> Now, in an interior environment (moisture not an issue), I'm
>>>>>>>> curious
>>>>>>>> about laminating an approx. 4' x 6' area of plywood with some other
>>>>>>>> thin-ish, or even not so thin-ish material -- from formica
>>>>>>>> laminates,
>>>>>>>> to .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>>>>>>>>
>>>>>>>> I recall carpenters using gobs of white elmers glue for
>>>>>>>> large-contact
>>>>>>>> wood areas, in building mezzanines in lofts, etc. Then there is
>>>>>>>> elmer's
>>>>>>>> carpenter's/wood glue, mastics for tile (what's a mastic,
>>>>>>>> inyway??),
>>>>>>>> epoxies, a zillion other adhesives.
>>>>>>>
>>>>>>> Mastic is a pasty material. Like linoleum paste...Liquid
>>>>>>> Nails...etc.
>>>>>>> __________________
>>>>>>>
>>>>>>>> The general Q is: when to use what for what?
>>>>>>>
>>>>>>> http://www.thistothat.com/
>>>>>>>
>>>>>>> For most of the things you mentioned, contact cement.
>>>>>>> _________________
>>>>>>
>>>>>> Contact cement would, I think, work well for 030 aluminum to one side
>>>>>> of
>>>>>> 1/4 plywood, where the wood would have a chance to flex. It may work
>>>>>> on
>>>>>> 1/2" plywood if the bond isn't heavily stressed.
>>>>>
>>>>> You're saying the bond would be less stressed with thinner ply than
>>>>> thicker??
>>>>> That seems counter-intuitive!
>>>>
>>>> Tim is right.
>>>
>>> Because there's less distance to the neutral axis?
>>
>> No, because the force is a product of the volume of the material that's
>> trying to stretch or shrink, and thicker material exerts more force.
>
> Well, in the case of pure flex, won't a thicker material flex less,
> thereby introducing less force?

Thinner gives more, so it won't load the aluminum-to-wood bond as much.

> Seems like an optimization problem here.....
> Also, by definition, distance from the neutral axis would have SOME
> contribution, no?

Let's not go there. We'd need pictures and I'm not up for it.

>
>>
>>> If I'm right, do I get a prize??
>>
>> When you're right, we'll consider it. d8-)
>
> Will I get to specify her dimensions?

And degrees of firmness. Do you prefer inflatable or foam-filled?

--
Ed Huntress




> --
> EA
>
>>>>
>>>>>
>>>>>
>>>>> But I think you'd
>>>>>> overcome the strength of the bond if you tried it on both sides, and
>>>>>> then
>>>>>> loaded things heavily.
>>>>>
>>>>> Iow, you advise against Robatoy's advice of laminating both sides?
>>>>> Reason?
>>>>>
>>>>>>
>>>>>> 'course, a quick look at yield strengths of Al and contact cement,
>>>>>> plus
>>>>>> some calculations, would tell you what's what.
>>>>>
>>>>> 4 ft x 6 ft is a lot of contact area. There will be some flex, but
>>>>> not like bending anything into a U.
>>>>> I'm thinking over a 4-6 ft dimension, occasional flex of mebbe an inch
>>>>> or two.
>>>>> --
>>>>> EA
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>
>>>>>> --
>>>>>> Tim Wescott
>>>>>> Control system and signal processing consulting
>>>>>> www.wescottdesign.com
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>
>

"Ed Huntress" <[email protected]> wrote in message
news:[email protected]...
>
> "Existential Angst" <[email protected]> wrote in message
> news:[email protected]...
>> "Ed Huntress" <[email protected]> wrote in message
>> news:[email protected]...
>>>
>>> "Existential Angst" <[email protected]> wrote in message
>>> news:[email protected]...
>>>> "Robatoy" <[email protected]> wrote in message
>>>> news:[email protected]...
>>>> On Jul 11, 10:54 pm, "Existential Angst" <[email protected]> wrote:
>>>>
>>>>> Any opinions on this?
>>>>
>>>> Yes. Many opinions. Just make sure that when laminating dissimilar
>>>> materials, to do both sides of the substrate, a 'balance' sheet.
>>>> ==========================================
>>>>
>>>> A very inneresting idea, altho in this case it will likely add
>>>> substantially to costs.
>>>> But mebbe a workable compromise is to laminate both sides, but not with
>>>> identical materials.
>>>> Proly an ongoing experiment.
>>>> But I do hear the demands of symmetry.... :)
>>>>
>>>>
>>>>
>>>> Trying to get away without one is foolish. In case of laminate, just a
>>>> cheap discontinued colour will suffice.
>>>> ===========================================
>>>>
>>>> In non-stress situations, like countertops, one-sided lamination seems
>>>> OK, but mebbe even there, two-sided lamination might help longevity
>>>> (warping, etc)..
>>>>
>>>>
>>>>
>>>> Also, look into Wilsonart 3000 adhesive. Water based, will stick
>>>> anything to anything (other than greasy plastics).
>>>> Lots of open time and a decent roller which will allow your body
>>>> weight to do the work is all you need.
>>>> Wilsonart 3000 is NOT contact cement but works a bit like it. One side
>>>> of the joint has to have minimal porosity.
>>>> ==============================================
>>>>
>>>> Will look into Wilsonart.
>>>>
>>>> What does "contact cement" connote, adhesive-wise? Is it a specific
>>>> genre, or are there a variety of types?
>>>> --
>>>> EA
>>>
>>> There are a several types. They have great relative peel and cleavage
>>> strength, but they yield a bit in shear. You want that with a countertop
>>> or you'd have warping problems.
>>>
>>> EA, you've asked a question that could go around in circles for a long
>>> time. Why don't you just tell us what it is you're trying to accomplish?
>>> That will narrow it down.
>>>
>>> As for being complicated, back in '78 or '79 I wrote a 16-page Special
>>> Report for _American Machinist_, titled "Adhesives in Metalworking," or
>>> something like that. I took four months to research it and I travelled
>>> all over the country, visiting engineering companies and suppliers who
>>> work at the high-performance end of the business. My report had so many
>>> elements in it, it was hard to keep it organized. And it just scratched
>>> the surface of the subject.
>>
>> There is no end of complexity in chemistry. I worked with a guy whose
>> specialty was a single effing orbital of the copper atom under specific
>> energy conditions..... goodgawd......
>>
>>>
>>> You're right, it is a very complicated subject. If you've ever read the
>>> reports on adhesives from the USDA Forest Products Laboratory, you know
>>> they're long -- and excellent. And that's just for wood and wood
>>> composites. When you get metal and plastics involved, the complexity
>>> compounds.
>>>
>>> That is, if you need high performance. The gummy glues, like contact
>>> cement and consumer-grade moisture-cure polyurethanes, solve a hundred
>>> different problems very neatly. But that's because most applications
>>> only require one or two types of strength -- in their case, it's mostly
>>> peel and cleavage, which are the toughest kinds of strength to get,
>>> usually, when you're bonding dissimilar materials. Contact cement is not
>>> a strong adhesive in engineering terms. But it may well be the
>>> strongest, and the best, for your application.
>>>
>>> So tell us what the application is.
>>
>> Well, I can't spill ALL the beans..... :) :)
>>
>> But basically it is a semi-portable jungle-jim-type apparatus, that needs
>> to be stabilized by a base, as the user will be pushing/pulling on the
>> apparatus, and the user's bodyweight is often what will prevent tipping.
>> True, I could make the apparatus itself 1,000# or so, and then I wouldn't
>> need a base..... LOL
>>
>> The base has "guy poles" and gussets to the apparatus itself, so in
>> actuality, the base can be surprisingly thin and function pretty well,
>> but of course not too thin. I was frankly quite surprised that the 1/2
>> ply works so well.
>>
>> So there is some flex in the base, on the order of a cupla inches over a
>> 4 ft to 6 ft dimension, but nothing like a foot.
>>
>> My laminating jihad here is in lieu of having to finish the ply.
>> Ordinary ply (one "good" face), with boucou coats of poly, actually turns
>> out VERY nicely, but goddamm, what a pita!! -- and ultimately proly perty
>> costly ito production. I'm looking for more of a slam/dunk solution, as
>> well as some alternative solutions ito style, interior design, etc.
>>
>> So dats the overall context. I have some neat solutions for capping the
>> edges, etc, which is another story, but which also lends to the rigidity.
>> Heh, I could also get away with no adhesive at all, because of how the
>> edging is finished, and, if shear is really such a big deal (and would
>> destroy the ply over time in the flexing process), then mebbe the
>> solution is to omit the adhesive and just live without the additional
>> stiffness of unitized members.
>
> Ok, the answer is clear. You want a pre-finished, overlaid plywood. You
> will kick yourself if you find the right material *after* you've screwed
> around trying to laminate it yourself. It will be cheaper in the long run,
> and maybe in the short run.
>
> Start Googling for overlaid plywood. There are many types.
>
> Without getting into the engineering too much, consider this: You know
> that the stiffness (and strength) increases with the cube of the
> thickness. So a small increase in the ply thickness will be as good as a
> thinner, fancy, two-sided laminate. As for one side versus two, the
> reasons for two sides are to minimize warping and to get MUCH more
> strength from the compression strength of the side that's in compression.
> Plywood's compression strength ain't all that great. But if you aren't
> loading it too hard (you aren't), compression stength should not come into
> play. One-sided should do it. Warping probably will not be a problem.
>
> BUT....and this is a big butt....the stiffness/weight ratio of plywood is
> HIGHER than medium-grade foam-core fiberglass laminate. No kidding. You
> need a fancy laminate, with high-density foam and Kevlar/carbon to produce
> better stiffness/weight than ply. That's why racing dinghies (noteably
> International 14s) are stiffer when made of cold-molded plywood than when
> made of fiberglass. (And they last much longer, too, but that's another
> story).
>
> So go for ply, and any benefits you get from a pre-overlaid surface will
> be cosmetic. That's all you need. If you want more stiffness, go for
> thicker ply. If you're buying inch-graded ply and you want just a little
> more, get some metric stuff.
>
> As for the overlay, it depends on how much dent and ding resistance you
> need. Resin-coated paper looks nice and takes paint well but it dents
> easily. MDO is slick as a baby's butt but it, too, dings easily. The thin
> melamine surfaces also ding easily, but they're cheap and they look nice
> until you stick something hard into them. The thin melamine is great, too,
> on MDF and particle board, but the first isn't very strong and the latter
> is heavy as sin. Plywood is much stronger and lighter. Thick melamine
> overlay can be expensive but it's nice.
>
> You'll be much happier with overlay, I'm sure. Just look around to find
> the right one.

DAMN YOU, Ed..... JUST when I was about to order my .032 aluminum!!!!
Gawd, I waffle enough already, WITHOUT good advice.... :)

Ackshooly, I'm building a bunch of these, and I sort of have to experiment
with aluminum anyway, so nothing is really lost, but I certainly will
research the overlaid ply, as I proly will have call to deliver a variety of
base surfaces/finishes.

>
>>
>> We'll see what happens. Heh, you want a unit??
>> It's basically the portable version of the stuff I've been building, that
>> I offered you once before -- which you graciously declined..... :) :)
>> Oh, and for YOU, FREE INSTALLATION!!!!
>
> I'd love one. But if you saw how small my house is, and how my shop is
> already sort of multi-tiered, you'd realize why I graciously decline.
>
> Besides, what I need is not a gym. It's joint and tendon therapy. d8-)

Well, if you recall, my original stuff is for a doorway, and a very large
part of its utility is precisely for rehab-type applications, of atrophied
muscle, joints, etc. Really VERY elegant, a virtual/literal ZERO footprint.
Heh, and not-bad machining!!!

The offer still stands. BottleBob has one, Gary Knutson has one -- oh, and
Tom Brewer has one, who REALLY had some rehab issues....
You can talk to them for how they use my ditties, see if you can use one.
BB uses it, ostensibly preparing for Olympic events.... LOL

I'm 10 mins from the GWB, so if yer ever around this way, stop by. I proly
have the most sophisticated shop ever crammed into an Englich Tudor.... And
you can see the various installations of my Folly.
All gratis, I'll even come out there and put it up, altho the doorway
version is literally a 5 min install in a wooden doorway.

However, degenerative-type joint disease is a difficult bear for any type of
correction, rehab, but even in this context, I believe my stuff would have
at least some utility, just not the extraordinary utility as in other
scenarios.
--
EA

>
>>
>> So how do you resolve the disparate opinion from Tim and Robatoy, ito of
>> symmetrical lamination?
>
> See above. There is more to it, but we're not engineering aircraft wings
> or racing boats.
>
> --
> Ed Huntress
>
>
>> --
>> EA
>
>

<[email protected]> wrote in message
news:e264f1cc-fa4d-4af4-b42a-758a0f2d2d4e@m18g2000vbl.googlegroups.com...
On Jul 11, 8:54 pm, "Existential Angst" <[email protected]> wrote:
> Awl --
>
> Previously (on RW), I asked about coatings, waterproofing plywood.
>
> Now, in an interior environment (moisture not an issue), I'm curious about
> laminating an approx. 4' x 6' area of plywood with some other thin-ish, or
> even not so thin-ish material -- from formica laminates, to .030 SS or
> Alum
> sheet, to 1/4" rubberized tile, linoleum.
>
> I recall carpenters using gobs of white elmers glue for large-contact wood
> areas, in building mezzanines in lofts, etc.
> Then there is elmer's carpenter's/wood glue, mastics for tile (what's a
> mastic, inyway??), epoxies, a zillion other adhesives.
>
> The general Q is: when to use what for what?
>
> For example, in the .030 SS/Alum I will place over 1/2" ply, I would like
> to
> be able to just roll on some suitable adhesive over the full 4x6 area, and
> press them together, proly via weight plates.
> What would good choices be? How thick?
>
> Interestingly, an increase in thickness from ..5 to .532 will generate
> about
> a 13% increase in stiffness, since stiffness is proportional to the square
> of thickness, but ONLY if there is no slippage between the two layers.
> Thus, the requirement for full-surface bonding, via adhesive.
>
> Ackshooly, that 13% inc in stiffness presumes similar materials. I
> measured
> that 1/4" alum plate is as stiff or stiffer than decent 1/2" ply, so the
> increase in stiffness is likely to be a bit more than 13%.
>
> Inyway, I'd like an idea of how to gauge the type of adhesive to
> application. Bang fer the buck is always good, as well.
>
> Along these lines, I see all kinds of two-part epoxies, specialized for
> wood, metal, ceramics/glass, etc.
> Afaict, they all work the same on everything, with perhaps the exception
> of
> things like nylon, delrin, other "greasy" plastics. Any opinions on this?
> --
> EA

>If you want stiffness out of wood construction, look up "torsion
>box". Can be scaled to whatever size you want.
>I've seen the technique used for cantilevered shelves coming out of
>walls with no supports.
>
>Stan

Torsion boxes are great, but if you follow the whole thread, it sounds like
he needs something much thinner.

--
Ed Huntress

"Tim Wescott" <[email protected]> wrote in message
news:[email protected]...
> On 07/12/2011 08:14 AM, Ed Huntress wrote:
>> "Existential Angst"<[email protected]> wrote in message
>> news:[email protected]...
>>> "Ed Huntress"<[email protected]> wrote in message
>>> news:[email protected]...
>>>>
>>>> "Existential Angst"<[email protected]> wrote in message
>>>> news:[email protected]...
>>>>> "Tim"<[email protected]> wrote in message
>>>>> news:[email protected]...
>>>>>> On Tue, 12 Jul 2011 07:13:44 -0400, dadiOH wrote:
>>>>>>
>>>>>>> Existential Angst wrote:
>>>>>>>> Awl --
>>>>>>>>
>>>>>>>> Previously (on RW), I asked about coatings, waterproofing plywood.
>>>>>>>>
>>>>>>>> Now, in an interior environment (moisture not an issue), I'm
>>>>>>>> curious
>>>>>>>> about laminating an approx. 4' x 6' area of plywood with some other
>>>>>>>> thin-ish, or even not so thin-ish material -- from formica
>>>>>>>> laminates,
>>>>>>>> to .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>>>>>>>>
>>>>>>>> I recall carpenters using gobs of white elmers glue for
>>>>>>>> large-contact
>>>>>>>> wood areas, in building mezzanines in lofts, etc. Then there is
>>>>>>>> elmer's
>>>>>>>> carpenter's/wood glue, mastics for tile (what's a mastic,
>>>>>>>> inyway??),
>>>>>>>> epoxies, a zillion other adhesives.
>>>>>>>
>>>>>>> Mastic is a pasty material. Like linoleum paste...Liquid
>>>>>>> Nails...etc.
>>>>>>> __________________
>>>>>>>
>>>>>>>> The general Q is: when to use what for what?
>>>>>>>
>>>>>>> http://www.thistothat.com/
>>>>>>>
>>>>>>> For most of the things you mentioned, contact cement.
>>>>>>> _________________
>>>>>>
>>>>>> Contact cement would, I think, work well for 030 aluminum to one side
>>>>>> of
>>>>>> 1/4 plywood, where the wood would have a chance to flex. It may work
>>>>>> on
>>>>>> 1/2" plywood if the bond isn't heavily stressed.
>>>>>
>>>>> You're saying the bond would be less stressed with thinner ply than
>>>>> thicker??
>>>>> That seems counter-intuitive!
>>>>
>>>> Tim is right.
>>>
>>> Because there's less distance to the neutral axis?
>>
>> No, because the force is a product of the volume of the material that's
>> trying to stretch or shrink, and thicker material exerts more force.
>
> I dunno -- I was seeing it as the distance from the neutral axis. You
> can't increase the distance from the neutral axis without increasing
> volume, so they pretty much go together.

It's not the neutral axis that's determining the force. It's an integrated
value of all of the force exerted by the expanding wood from the bond plane
to the plane of the wood panel farthest from the aluminum. And all of that
force is applied to the bending resistance of the aluminum, through the glue
bond.

Compounding the effect is the greater leverage exerted by any expansion
force generated in the wood fibers farthest from the aluminum.

>
> I was saying that if you only put the aluminum on _one side_, _and_ you
> use something thinner than 1/2 inch, that you should be OK.

It would be less likely to sheer off.

> Basically, the aluminum is going to move a lot less than the wood. Only
> doing one side gives the wood an opportunity to move (and to bow with
> humidity), which relieves stress on the glue joint.

But the force is applied *to* the glue joint, as the wood tries to expand.
More wood, more force.

>
> Put Al on both sides of the wood and you're right back to gluing a strong
> thing to a weak thing with stuff of questionable strength -- so if you
> stress it to breaking, either the glue bond or the underlying wood is
> going to shear, or the glue on the compression side is going to let the
> aluminum lift and buckle, or the wood on the compression side is going to
> let the aluminum dig in and buckle.

True, but as others have said, it will be stiffer to begin with, and much
less vulnerable to expansion from changes in humidity.
>
> But (again) if rigidity is more important than strength, this may not be a
> bad way to go.

I think EA has a fairly low-tech application here. He can get away with a
lot, as long as the plywood is thick enough to provide the stiffness he
needs.

'Don't know why he's talking about aluminum, though. That's the biggest
bonding problem, and it has little else to offer to the application. It must
be something he isn't telling us. d8-)

--
Ed Huntress

>
> --
>
> Tim Wescott
> Wescott Design Services
> http://www.wescottdesign.com
>
> Do you need to implement control loops in software?
> "Applied Control Theory for Embedded Systems" was written for you.
> See details at http://www.wescottdesign.com/actfes/actfes.html

"Tim Wescott" <[email protected]> wrote in message
news:[email protected]...
> On 07/12/2011 08:12 AM, Existential Angst wrote:
>> "Ed Huntress"<[email protected]> wrote in message
>> news:[email protected]...
>>>
>>> "Existential Angst"<[email protected]> wrote in message
>>> news:[email protected]...
>>>> "Robatoy"<[email protected]> wrote in message
>>>> news:[email protected]...
>>>> On Jul 11, 10:54 pm, "Existential Angst"<[email protected]> wrote:
>>>>
>>>>> Any opinions on this?
>>>>
>>>> Yes. Many opinions. Just make sure that when laminating dissimilar
>>>> materials, to do both sides of the substrate, a 'balance' sheet.
>>>> ==========================================
>>>>
>>>> A very inneresting idea, altho in this case it will likely add
>>>> substantially to costs.
>>>> But mebbe a workable compromise is to laminate both sides, but not with
>>>> identical materials.
>>>> Proly an ongoing experiment.
>>>> But I do hear the demands of symmetry.... :)
>>>>
>>>>
>>>>
>>>> Trying to get away without one is foolish. In case of laminate, just a
>>>> cheap discontinued colour will suffice.
>>>> ===========================================
>>>>
>>>> In non-stress situations, like countertops, one-sided lamination seems
>>>> OK, but mebbe even there, two-sided lamination might help longevity
>>>> (warping, etc)..
>>>>
>>>>
>>>>
>>>> Also, look into Wilsonart 3000 adhesive. Water based, will stick
>>>> anything to anything (other than greasy plastics).
>>>> Lots of open time and a decent roller which will allow your body
>>>> weight to do the work is all you need.
>>>> Wilsonart 3000 is NOT contact cement but works a bit like it. One side
>>>> of the joint has to have minimal porosity.
>>>> ==============================================
>>>>
>>>> Will look into Wilsonart.
>>>>
>>>> What does "contact cement" connote, adhesive-wise? Is it a specific
>>>> genre, or are there a variety of types?
>>>> --
>>>> EA
>>>
>>> There are a several types. They have great relative peel and cleavage
>>> strength, but they yield a bit in shear. You want that with a countertop
>>> or you'd have warping problems.
>>>
>>> EA, you've asked a question that could go around in circles for a long
>>> time. Why don't you just tell us what it is you're trying to accomplish?
>>> That will narrow it down.
>>>
>>> As for being complicated, back in '78 or '79 I wrote a 16-page Special
>>> Report for _American Machinist_, titled "Adhesives in Metalworking," or
>>> something like that. I took four months to research it and I travelled
>>> all
>>> over the country, visiting engineering companies and suppliers who work
>>> at
>>> the high-performance end of the business. My report had so many elements
>>> in it, it was hard to keep it organized. And it just scratched the
>>> surface
>>> of the subject.
>>
>> There is no end of complexity in chemistry. I worked with a guy whose
>> specialty was a single effing orbital of the copper atom under specific
>> energy conditions..... goodgawd......
>>
>>>
>>> You're right, it is a very complicated subject. If you've ever read the
>>> reports on adhesives from the USDA Forest Products Laboratory, you know
>>> they're long -- and excellent. And that's just for wood and wood
>>> composites. When you get metal and plastics involved, the complexity
>>> compounds.
>>>
>>> That is, if you need high performance. The gummy glues, like contact
>>> cement and consumer-grade moisture-cure polyurethanes, solve a hundred
>>> different problems very neatly. But that's because most applications
>>> only
>>> require one or two types of strength -- in their case, it's mostly peel
>>> and cleavage, which are the toughest kinds of strength to get, usually,
>>> when you're bonding dissimilar materials. Contact cement is not a strong
>>> adhesive in engineering terms. But it may well be the strongest, and the
>>> best, for your application.
>>>
>>> So tell us what the application is.
>>
>> Well, I can't spill ALL the beans..... :) :)
>>
>> But basically it is a semi-portable jungle-jim-type apparatus, that needs
>> to
>> be stabilized by a base, as the user will be pushing/pulling on the
>> apparatus, and the user's bodyweight is often what will prevent tipping.
>> True, I could make the apparatus itself 1,000# or so, and then I wouldn't
>> need a base..... LOL
>>
>> The base has "guy poles" and gussets to the apparatus itself, so in
>> actuality, the base can be surprisingly thin and function pretty well,
>> but
>> of course not too thin. I was frankly quite surprised that the 1/2 ply
>> works so well.
>>
>> So there is some flex in the base, on the order of a cupla inches over a
>> 4
>> ft to 6 ft dimension, but nothing like a foot.
>>
>> My laminating jihad here is in lieu of having to finish the ply.
>> Ordinary
>> ply (one "good" face), with boucou coats of poly, actually turns out VERY
>> nicely, but goddamm, what a pita!! -- and ultimately proly perty costly
>> ito
>> production. I'm looking for more of a slam/dunk solution, as well as
>> some
>> alternative solutions ito style, interior design, etc.
>>
>> So dats the overall context. I have some neat solutions for capping the
>> edges, etc, which is another story, but which also lends to the rigidity.
>> Heh, I could also get away with no adhesive at all, because of how the
>> edging is finished, and, if shear is really such a big deal (and would
>> destroy the ply over time in the flexing process), then mebbe the
>> solution
>> is to omit the adhesive and just live without the additional stiffness of
>> unitized members.
>>
>> We'll see what happens. Heh, you want a unit??
>> It's basically the portable version of the stuff I've been building, that
>> I
>> offered you once before -- which you graciously declined..... :) :)
>> Oh, and for YOU, FREE INSTALLATION!!!!
>>
>> So how do you resolve the disparate opinion from Tim and Robatoy, ito of
>> symmetrical lamination?
>
> Robatoy is telling you how to do it if you're using ordinary stuff that
> you might laminate to ply (read: stuff that normal folks normally use),
> and that you don't want to warp.
>
> I'm specifically addressing how you might do it if you're laminating
> something thats Really Fricking Strong* compared to plywood, and how you
> would do it in such a way that nothing actually breaks. In other words --
> I'm having fun trying to figure out what would essentially be an aviation
> or similar application, he's trying to tell you how to make things work
> right for something much like what you're doing.
>
> I think you want to go with something like melamine or Formica or other
> 'normal' hard surface for wood, that's not going to lend much strength to
> the wood (and hence isn't going to stress the glue too much). Vinyl,
> maybe. That'll go on with ordinary contact cement, it'll stretch and
> shrink with the wood, and it'll look good.
>
> Make extra special delux units with hardwood veneer and varnish --
> charge $$ extra.
>
> * That's an engineering term, by the way.

Then it needs an oh-ficial abbreviation: RF'gS. :)

So then, if I insist on using an alum or SS "laminate", mebbe the best
strategy is to forego the adhesive altogether, as I think I mentioned to Ed
H.
The system is already stiff enough, and altho it pains me forego a cubed
increase in stiffness, it beats tearing stuff apart, *after* a lot of pita
labor and effort.

Would you agree with that?

Btw, vinyl/rubberish coverings are also a very real option, with also
sidesteps the whole shear/adhesive issue, fwi now understand.
--
EA

>
> --
>
> Tim Wescott
> Wescott Design Services
> http://www.wescottdesign.com
>
> Do you need to implement control loops in software?
> "Applied Control Theory for Embedded Systems" was written for you.
> See details at http://www.wescottdesign.com/actfes/actfes.html

"Ed Huntress" <[email protected]> wrote in message
news:[email protected]...
>
> "Tim Wescott" <[email protected]> wrote in message
> news:[email protected]...
>> On 07/12/2011 08:14 AM, Ed Huntress wrote:
>>> "Existential Angst"<[email protected]> wrote in message
>>> news:[email protected]...
>>>> "Ed Huntress"<[email protected]> wrote in message
>>>> news:[email protected]...
>>>>>
>>>>> "Existential Angst"<[email protected]> wrote in message
>>>>> news:[email protected]...
>>>>>> "Tim"<[email protected]> wrote in message
>>>>>> news:[email protected]...
>>>>>>> On Tue, 12 Jul 2011 07:13:44 -0400, dadiOH wrote:
>>>>>>>
>>>>>>>> Existential Angst wrote:
>>>>>>>>> Awl --
>>>>>>>>>
>>>>>>>>> Previously (on RW), I asked about coatings, waterproofing plywood.
>>>>>>>>>
>>>>>>>>> Now, in an interior environment (moisture not an issue), I'm
>>>>>>>>> curious
>>>>>>>>> about laminating an approx. 4' x 6' area of plywood with some
>>>>>>>>> other
>>>>>>>>> thin-ish, or even not so thin-ish material -- from formica
>>>>>>>>> laminates,
>>>>>>>>> to .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>>>>>>>>>
>>>>>>>>> I recall carpenters using gobs of white elmers glue for
>>>>>>>>> large-contact
>>>>>>>>> wood areas, in building mezzanines in lofts, etc. Then there is
>>>>>>>>> elmer's
>>>>>>>>> carpenter's/wood glue, mastics for tile (what's a mastic,
>>>>>>>>> inyway??),
>>>>>>>>> epoxies, a zillion other adhesives.
>>>>>>>>
>>>>>>>> Mastic is a pasty material. Like linoleum paste...Liquid
>>>>>>>> Nails...etc.
>>>>>>>> __________________
>>>>>>>>
>>>>>>>>> The general Q is: when to use what for what?
>>>>>>>>
>>>>>>>> http://www.thistothat.com/
>>>>>>>>
>>>>>>>> For most of the things you mentioned, contact cement.
>>>>>>>> _________________
>>>>>>>
>>>>>>> Contact cement would, I think, work well for 030 aluminum to one
>>>>>>> side
>>>>>>> of
>>>>>>> 1/4 plywood, where the wood would have a chance to flex. It may
>>>>>>> work
>>>>>>> on
>>>>>>> 1/2" plywood if the bond isn't heavily stressed.
>>>>>>
>>>>>> You're saying the bond would be less stressed with thinner ply than
>>>>>> thicker??
>>>>>> That seems counter-intuitive!
>>>>>
>>>>> Tim is right.
>>>>
>>>> Because there's less distance to the neutral axis?
>>>
>>> No, because the force is a product of the volume of the material that's
>>> trying to stretch or shrink, and thicker material exerts more force.
>>
>> I dunno -- I was seeing it as the distance from the neutral axis. You
>> can't increase the distance from the neutral axis without increasing
>> volume, so they pretty much go together.
>
> It's not the neutral axis that's determining the force. It's an integrated
> value of all of the force exerted by the expanding wood from the bond
> plane to the plane of the wood panel farthest from the aluminum. And all
> of that force is applied to the bending resistance of the aluminum,
> through the glue bond.
>
> Compounding the effect is the greater leverage exerted by any expansion
> force generated in the wood fibers farthest from the aluminum.
>
>>
>> I was saying that if you only put the aluminum on _one side_, _and_ you
>> use something thinner than 1/2 inch, that you should be OK.
>
> It would be less likely to sheer off.
>
>> Basically, the aluminum is going to move a lot less than the wood. Only
>> doing one side gives the wood an opportunity to move (and to bow with
>> humidity), which relieves stress on the glue joint.
>
> But the force is applied *to* the glue joint, as the wood tries to expand.
> More wood, more force.
>
>>
>> Put Al on both sides of the wood and you're right back to gluing a strong
>> thing to a weak thing with stuff of questionable strength -- so if you
>> stress it to breaking, either the glue bond or the underlying wood is
>> going to shear, or the glue on the compression side is going to let the
>> aluminum lift and buckle, or the wood on the compression side is going to
>> let the aluminum dig in and buckle.
>
> True, but as others have said, it will be stiffer to begin with, and much
> less vulnerable to expansion from changes in humidity.
>>
>> But (again) if rigidity is more important than strength, this may not be
>> a bad way to go.
>
> I think EA has a fairly low-tech application here. He can get away with a
> lot, as long as the plywood is thick enough to provide the stiffness he
> needs.
>
> 'Don't know why he's talking about aluminum, though. That's the biggest
> bonding problem, and it has little else to offer to the application. It
> must be something he isn't telling us. d8-)

Uhhh..... it's SHINY???? :)
Well, at least it starts off shiny!!
And it's half the price of same-thickness SS.

Not absolutely wedded to any single strategy, as there are no doubt lotsa
unforeseen things that will make one strategy more do-able than another.
And regardless of what the laminating strategy is, I have the luxury of
using no adhesive at all, due to the way the edges are treated.

Lotsa options here, super info, appreciate all the input.
--
EA



>
> --
> Ed Huntress
>
>>
>> --
>>
>> Tim Wescott
>> Wescott Design Services
>> http://www.wescottdesign.com
>>
>> Do you need to implement control loops in software?
>> "Applied Control Theory for Embedded Systems" was written for you.
>> See details at http://www.wescottdesign.com/actfes/actfes.html
>
>

"Existential Angst" <[email protected]> wrote in message
news:[email protected]...
> "Ed Huntress" <[email protected]> wrote in message
> news:[email protected]...
>>
>> "Tim Wescott" <[email protected]> wrote in message
>> news:[email protected]...
>>> On 07/12/2011 08:14 AM, Ed Huntress wrote:
>>>> "Existential Angst"<[email protected]> wrote in message
>>>> news:[email protected]...
>>>>> "Ed Huntress"<[email protected]> wrote in message
>>>>> news:[email protected]...
>>>>>>
>>>>>> "Existential Angst"<[email protected]> wrote in message
>>>>>> news:[email protected]...
>>>>>>> "Tim"<[email protected]> wrote in message
>>>>>>> news:[email protected]...
>>>>>>>> On Tue, 12 Jul 2011 07:13:44 -0400, dadiOH wrote:
>>>>>>>>
>>>>>>>>> Existential Angst wrote:
>>>>>>>>>> Awl --
>>>>>>>>>>
>>>>>>>>>> Previously (on RW), I asked about coatings, waterproofing
>>>>>>>>>> plywood.
>>>>>>>>>>
>>>>>>>>>> Now, in an interior environment (moisture not an issue), I'm
>>>>>>>>>> curious
>>>>>>>>>> about laminating an approx. 4' x 6' area of plywood with some
>>>>>>>>>> other
>>>>>>>>>> thin-ish, or even not so thin-ish material -- from formica
>>>>>>>>>> laminates,
>>>>>>>>>> to .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>>>>>>>>>>
>>>>>>>>>> I recall carpenters using gobs of white elmers glue for
>>>>>>>>>> large-contact
>>>>>>>>>> wood areas, in building mezzanines in lofts, etc. Then there is
>>>>>>>>>> elmer's
>>>>>>>>>> carpenter's/wood glue, mastics for tile (what's a mastic,
>>>>>>>>>> inyway??),
>>>>>>>>>> epoxies, a zillion other adhesives.
>>>>>>>>>
>>>>>>>>> Mastic is a pasty material. Like linoleum paste...Liquid
>>>>>>>>> Nails...etc.
>>>>>>>>> __________________
>>>>>>>>>
>>>>>>>>>> The general Q is: when to use what for what?
>>>>>>>>>
>>>>>>>>> http://www.thistothat.com/
>>>>>>>>>
>>>>>>>>> For most of the things you mentioned, contact cement.
>>>>>>>>> _________________
>>>>>>>>
>>>>>>>> Contact cement would, I think, work well for 030 aluminum to one
>>>>>>>> side
>>>>>>>> of
>>>>>>>> 1/4 plywood, where the wood would have a chance to flex. It may
>>>>>>>> work
>>>>>>>> on
>>>>>>>> 1/2" plywood if the bond isn't heavily stressed.
>>>>>>>
>>>>>>> You're saying the bond would be less stressed with thinner ply than
>>>>>>> thicker??
>>>>>>> That seems counter-intuitive!
>>>>>>
>>>>>> Tim is right.
>>>>>
>>>>> Because there's less distance to the neutral axis?
>>>>
>>>> No, because the force is a product of the volume of the material that's
>>>> trying to stretch or shrink, and thicker material exerts more force.
>>>
>>> I dunno -- I was seeing it as the distance from the neutral axis. You
>>> can't increase the distance from the neutral axis without increasing
>>> volume, so they pretty much go together.
>>
>> It's not the neutral axis that's determining the force. It's an
>> integrated value of all of the force exerted by the expanding wood from
>> the bond plane to the plane of the wood panel farthest from the aluminum.
>> And all of that force is applied to the bending resistance of the
>> aluminum, through the glue bond.
>>
>> Compounding the effect is the greater leverage exerted by any expansion
>> force generated in the wood fibers farthest from the aluminum.
>>
>>>
>>> I was saying that if you only put the aluminum on _one side_, _and_ you
>>> use something thinner than 1/2 inch, that you should be OK.
>>
>> It would be less likely to sheer off.
>>
>>> Basically, the aluminum is going to move a lot less than the wood. Only
>>> doing one side gives the wood an opportunity to move (and to bow with
>>> humidity), which relieves stress on the glue joint.
>>
>> But the force is applied *to* the glue joint, as the wood tries to
>> expand. More wood, more force.
>>
>>>
>>> Put Al on both sides of the wood and you're right back to gluing a
>>> strong thing to a weak thing with stuff of questionable strength -- so
>>> if you stress it to breaking, either the glue bond or the underlying
>>> wood is going to shear, or the glue on the compression side is going to
>>> let the aluminum lift and buckle, or the wood on the compression side is
>>> going to let the aluminum dig in and buckle.
>>
>> True, but as others have said, it will be stiffer to begin with, and much
>> less vulnerable to expansion from changes in humidity.
>>>
>>> But (again) if rigidity is more important than strength, this may not be
>>> a bad way to go.
>>
>> I think EA has a fairly low-tech application here. He can get away with a
>> lot, as long as the plywood is thick enough to provide the stiffness he
>> needs.
>>
>> 'Don't know why he's talking about aluminum, though. That's the biggest
>> bonding problem, and it has little else to offer to the application. It
>> must be something he isn't telling us. d8-)
>
> Uhhh..... it's SHINY???? :)

Damn. I didn't think about that. d8-)

> Well, at least it starts off shiny!!
> And it's half the price of same-thickness SS.
>
> Not absolutely wedded to any single strategy, as there are no doubt lotsa
> unforeseen things that will make one strategy more do-able than another.
> And regardless of what the laminating strategy is, I have the luxury of
> using no adhesive at all, due to the way the edges are treated.
>
> Lotsa options here, super info, appreciate all the input.
> --
> EA

Sometimes it's good to just fish around like that, to hear some options you
might not have considered. But now you can get down to looking at your
objectives in light of what's available.

I still think that laminating it yourself is going to be a losing
proposition relative to buying overlaid ply, but you can check out those
options for yourself.

Let us know how it works out.

--
Ed Huntress

"Existential Angst" <[email protected]> wrote in message
news:[email protected]...
> "Ed Huntress" <[email protected]> wrote in message
> news:[email protected]...
>>
>> "Existential Angst" <[email protected]> wrote in message
>> news:[email protected]...
>>> "Ed Huntress" <[email protected]> wrote in message
>>> news:[email protected]...
>>>>
>>>> "Existential Angst" <[email protected]> wrote in message
>>>> news:[email protected]...
>>>>> "Robatoy" <[email protected]> wrote in message
>>>>> news:[email protected]...
>>>>> On Jul 11, 10:54 pm, "Existential Angst" <[email protected]> wrote:
>>>>>
>>>>>> Any opinions on this?
>>>>>
>>>>> Yes. Many opinions. Just make sure that when laminating dissimilar
>>>>> materials, to do both sides of the substrate, a 'balance' sheet.
>>>>> ==========================================
>>>>>
>>>>> A very inneresting idea, altho in this case it will likely add
>>>>> substantially to costs.
>>>>> But mebbe a workable compromise is to laminate both sides, but not
>>>>> with identical materials.
>>>>> Proly an ongoing experiment.
>>>>> But I do hear the demands of symmetry.... :)
>>>>>
>>>>>
>>>>>
>>>>> Trying to get away without one is foolish. In case of laminate, just a
>>>>> cheap discontinued colour will suffice.
>>>>> ===========================================
>>>>>
>>>>> In non-stress situations, like countertops, one-sided lamination seems
>>>>> OK, but mebbe even there, two-sided lamination might help longevity
>>>>> (warping, etc)..
>>>>>
>>>>>
>>>>>
>>>>> Also, look into Wilsonart 3000 adhesive. Water based, will stick
>>>>> anything to anything (other than greasy plastics).
>>>>> Lots of open time and a decent roller which will allow your body
>>>>> weight to do the work is all you need.
>>>>> Wilsonart 3000 is NOT contact cement but works a bit like it. One side
>>>>> of the joint has to have minimal porosity.
>>>>> ==============================================
>>>>>
>>>>> Will look into Wilsonart.
>>>>>
>>>>> What does "contact cement" connote, adhesive-wise? Is it a specific
>>>>> genre, or are there a variety of types?
>>>>> --
>>>>> EA
>>>>
>>>> There are a several types. They have great relative peel and cleavage
>>>> strength, but they yield a bit in shear. You want that with a
>>>> countertop or you'd have warping problems.
>>>>
>>>> EA, you've asked a question that could go around in circles for a long
>>>> time. Why don't you just tell us what it is you're trying to
>>>> accomplish? That will narrow it down.
>>>>
>>>> As for being complicated, back in '78 or '79 I wrote a 16-page Special
>>>> Report for _American Machinist_, titled "Adhesives in Metalworking," or
>>>> something like that. I took four months to research it and I travelled
>>>> all over the country, visiting engineering companies and suppliers who
>>>> work at the high-performance end of the business. My report had so many
>>>> elements in it, it was hard to keep it organized. And it just scratched
>>>> the surface of the subject.
>>>
>>> There is no end of complexity in chemistry. I worked with a guy whose
>>> specialty was a single effing orbital of the copper atom under specific
>>> energy conditions..... goodgawd......
>>>
>>>>
>>>> You're right, it is a very complicated subject. If you've ever read the
>>>> reports on adhesives from the USDA Forest Products Laboratory, you know
>>>> they're long -- and excellent. And that's just for wood and wood
>>>> composites. When you get metal and plastics involved, the complexity
>>>> compounds.
>>>>
>>>> That is, if you need high performance. The gummy glues, like contact
>>>> cement and consumer-grade moisture-cure polyurethanes, solve a hundred
>>>> different problems very neatly. But that's because most applications
>>>> only require one or two types of strength -- in their case, it's mostly
>>>> peel and cleavage, which are the toughest kinds of strength to get,
>>>> usually, when you're bonding dissimilar materials. Contact cement is
>>>> not a strong adhesive in engineering terms. But it may well be the
>>>> strongest, and the best, for your application.
>>>>
>>>> So tell us what the application is.
>>>
>>> Well, I can't spill ALL the beans..... :) :)
>>>
>>> But basically it is a semi-portable jungle-jim-type apparatus, that
>>> needs to be stabilized by a base, as the user will be pushing/pulling on
>>> the apparatus, and the user's bodyweight is often what will prevent
>>> tipping.
>>> True, I could make the apparatus itself 1,000# or so, and then I
>>> wouldn't need a base..... LOL
>>>
>>> The base has "guy poles" and gussets to the apparatus itself, so in
>>> actuality, the base can be surprisingly thin and function pretty well,
>>> but of course not too thin. I was frankly quite surprised that the 1/2
>>> ply works so well.
>>>
>>> So there is some flex in the base, on the order of a cupla inches over a
>>> 4 ft to 6 ft dimension, but nothing like a foot.
>>>
>>> My laminating jihad here is in lieu of having to finish the ply.
>>> Ordinary ply (one "good" face), with boucou coats of poly, actually
>>> turns out VERY nicely, but goddamm, what a pita!! -- and ultimately
>>> proly perty costly ito production. I'm looking for more of a slam/dunk
>>> solution, as well as some alternative solutions ito style, interior
>>> design, etc.
>>>
>>> So dats the overall context. I have some neat solutions for capping the
>>> edges, etc, which is another story, but which also lends to the
>>> rigidity.
>>> Heh, I could also get away with no adhesive at all, because of how the
>>> edging is finished, and, if shear is really such a big deal (and would
>>> destroy the ply over time in the flexing process), then mebbe the
>>> solution is to omit the adhesive and just live without the additional
>>> stiffness of unitized members.
>>
>> Ok, the answer is clear. You want a pre-finished, overlaid plywood. You
>> will kick yourself if you find the right material *after* you've screwed
>> around trying to laminate it yourself. It will be cheaper in the long
>> run, and maybe in the short run.
>>
>> Start Googling for overlaid plywood. There are many types.
>>
>> Without getting into the engineering too much, consider this: You know
>> that the stiffness (and strength) increases with the cube of the
>> thickness. So a small increase in the ply thickness will be as good as a
>> thinner, fancy, two-sided laminate. As for one side versus two, the
>> reasons for two sides are to minimize warping and to get MUCH more
>> strength from the compression strength of the side that's in compression.
>> Plywood's compression strength ain't all that great. But if you aren't
>> loading it too hard (you aren't), compression stength should not come
>> into play. One-sided should do it. Warping probably will not be a
>> problem.
>>
>> BUT....and this is a big butt....the stiffness/weight ratio of plywood is
>> HIGHER than medium-grade foam-core fiberglass laminate. No kidding. You
>> need a fancy laminate, with high-density foam and Kevlar/carbon to
>> produce better stiffness/weight than ply. That's why racing dinghies
>> (noteably International 14s) are stiffer when made of cold-molded plywood
>> than when made of fiberglass. (And they last much longer, too, but that's
>> another story).
>>
>> So go for ply, and any benefits you get from a pre-overlaid surface will
>> be cosmetic. That's all you need. If you want more stiffness, go for
>> thicker ply. If you're buying inch-graded ply and you want just a little
>> more, get some metric stuff.
>>
>> As for the overlay, it depends on how much dent and ding resistance you
>> need. Resin-coated paper looks nice and takes paint well but it dents
>> easily. MDO is slick as a baby's butt but it, too, dings easily. The thin
>> melamine surfaces also ding easily, but they're cheap and they look nice
>> until you stick something hard into them. The thin melamine is great,
>> too, on MDF and particle board, but the first isn't very strong and the
>> latter is heavy as sin. Plywood is much stronger and lighter. Thick
>> melamine overlay can be expensive but it's nice.
>>
>> You'll be much happier with overlay, I'm sure. Just look around to find
>> the right one.
>
> DAMN YOU, Ed..... JUST when I was about to order my .032 aluminum!!!!
> Gawd, I waffle enough already, WITHOUT good advice.... :)
>
> Ackshooly, I'm building a bunch of these, and I sort of have to experiment
> with aluminum anyway, so nothing is really lost, but I certainly will
> research the overlaid ply, as I proly will have call to deliver a variety
> of base surfaces/finishes.
>
>>
>>>
>>> We'll see what happens. Heh, you want a unit??
>>> It's basically the portable version of the stuff I've been building,
>>> that I offered you once before -- which you graciously declined.....
>>> :) :)
>>> Oh, and for YOU, FREE INSTALLATION!!!!
>>
>> I'd love one. But if you saw how small my house is, and how my shop is
>> already sort of multi-tiered, you'd realize why I graciously decline.
>>
>> Besides, what I need is not a gym. It's joint and tendon therapy. d8-)
>
> Well, if you recall, my original stuff is for a doorway, and a very large
> part of its utility is precisely for rehab-type applications, of atrophied
> muscle, joints, etc. Really VERY elegant, a virtual/literal ZERO
> footprint.
> Heh, and not-bad machining!!!
>
> The offer still stands.

Ok, I'm convinced, and I need something that will fit. I'll come up there
sometime soon.

BottleBob has one, Gary Knutson has one -- oh, and
> Tom Brewer has one, who REALLY had some rehab issues....
> You can talk to them for how they use my ditties, see if you can use one.
> BB uses it, ostensibly preparing for Olympic events.... LOL
>
> I'm 10 mins from the GWB, so if yer ever around this way, stop by. I
> proly have the most sophisticated shop ever crammed into an Englich
> Tudor.... And you can see the various installations of my Folly.
> All gratis, I'll even come out there and put it up, altho the doorway
> version is literally a 5 min install in a wooden doorway.

I appreciate that, but I'll be coming up that way anyway, and there isn't
much to see here, since I just got rid of my mill, my surface grinder, and
two woodworking machines. I want to buy a new mill but not right now. I'm
just too busy to fool in the shop much. Even my bandsaw and tablesaw are
lying in pieces for an overhaul.

I'll be heading for IL in a few weeks (and I'll stop in to see Iggy again,
if he's around), and then I want to go up to Lime Rock Park. I'll either
stop in then or I'll make a special trip.

We'll be in touch.

>
> However, degenerative-type joint disease is a difficult bear for any type
> of correction, rehab, but even in this context, I believe my stuff would
> have at least some utility, just not the extraordinary utility as in other
> scenarios.

This isn't degenerative stuff, except plain 'ol age. I was sort of joking
about the joints. They're doing quite well. But I just got over Achilles
tendonitis (it took over 3 years to heal, and my doc was amazed that it
healed at all -- he was ready to put me under the knife). I'm recovering
from rotator-cuff tendonitis in one shoulder and unknown tendonitis in the
other. No more MRIs until I try rehabbing that sucker for a while.
Fortunately, my back is as good as a twenty-year-old's. I think that would
kill me if it ever went out.

I feel like a clapped-out racecar. Parts keep falling off, but they do make
me lighter. d8-)

--
Ed Huntress


> --
> EA
>
>>
>>>
>>> So how do you resolve the disparate opinion from Tim and Robatoy, ito of
>>> symmetrical lamination?
>>
>> See above. There is more to it, but we're not engineering aircraft wings
>> or racing boats.
>>
>> --
>> Ed Huntress
>>
>>
>>> --
>>> EA
>>
>>
>
>

On Jul 12, 1:39=A0am, Tim <[email protected]> wrote:
> ...>
> If "light and stiff" are what he's looking for, it'd certainly deliver. =
=A0
> But when it let go it'd let go with a bang, and there's all sorts of
> wrong with trying to bond wood to metal.
>
> --
> Tim Wescott

The temperature coefficients of expansion, for one.

jsw

On Jul 12, 11:30=A0am, "dadiOH" <[email protected]> wrote:

>
> Contact cement is hard to apply evenly and is messy: plan on throwing awa=
y
> any roller/brush used for application.

You are also hoping the cheap roller isn't made with pile stuck into
an adhesive that the solvent in the contact cement doesn't dissolve.
That way the roller itself will unroll, and then you're in trouble.

>=A0Porous surfaces will most likely
> require two coats. =A0Each surface needs to look glossy all over and must=
be
> dry enough so your finger doesn't stick.
>
> Others have suggested using paper slip sheets.

Nooooo paper slip sheets... they can get caught and tear. Dowels 5/16"
or bigger.=A0

> That will work but the thing
> about contact cement is, well, it bonds on contact. =A0I prefer to use do=
wels
> or sticks to keep the two surfaces well apart from each other until you a=
re
> ready to bond them. =A0I usually space them (dowels) 12-15" apart, depend=
s on
> the dowel diameter.
>
> Once you start bonding, start at the center and work out toward the ends =
to
> avoid trapping air. =A0Once all is bonded it needs to be *BONDED*. =A0Do =
that
> with a J-roller, lots of pressure; again, work from center out to the end=
s
> and edges. =A0You can also use a rubber mallet, roller is better.
>
J roller indeed. You obviously know your laminating stuff.

On 07/12/2011 08:12 AM, Existential Angst wrote:
> "Ed Huntress"<[email protected]> wrote in message
> news:[email protected]...
>>
>> "Existential Angst"<[email protected]> wrote in message
>> news:[email protected]...
>>> "Robatoy"<[email protected]> wrote in message
>>> news:[email protected]...
>>> On Jul 11, 10:54 pm, "Existential Angst"<[email protected]> wrote:
>>>
>>>> Any opinions on this?
>>>
>>> Yes. Many opinions. Just make sure that when laminating dissimilar
>>> materials, to do both sides of the substrate, a 'balance' sheet.
>>> ==========================================
>>>
>>> A very inneresting idea, altho in this case it will likely add
>>> substantially to costs.
>>> But mebbe a workable compromise is to laminate both sides, but not with
>>> identical materials.
>>> Proly an ongoing experiment.
>>> But I do hear the demands of symmetry.... :)
>>>
>>>
>>>
>>> Trying to get away without one is foolish. In case of laminate, just a
>>> cheap discontinued colour will suffice.
>>> ===========================================
>>>
>>> In non-stress situations, like countertops, one-sided lamination seems
>>> OK, but mebbe even there, two-sided lamination might help longevity
>>> (warping, etc)..
>>>
>>>
>>>
>>> Also, look into Wilsonart 3000 adhesive. Water based, will stick
>>> anything to anything (other than greasy plastics).
>>> Lots of open time and a decent roller which will allow your body
>>> weight to do the work is all you need.
>>> Wilsonart 3000 is NOT contact cement but works a bit like it. One side
>>> of the joint has to have minimal porosity.
>>> ==============================================
>>>
>>> Will look into Wilsonart.
>>>
>>> What does "contact cement" connote, adhesive-wise? Is it a specific
>>> genre, or are there a variety of types?
>>> --
>>> EA
>>
>> There are a several types. They have great relative peel and cleavage
>> strength, but they yield a bit in shear. You want that with a countertop
>> or you'd have warping problems.
>>
>> EA, you've asked a question that could go around in circles for a long
>> time. Why don't you just tell us what it is you're trying to accomplish?
>> That will narrow it down.
>>
>> As for being complicated, back in '78 or '79 I wrote a 16-page Special
>> Report for _American Machinist_, titled "Adhesives in Metalworking," or
>> something like that. I took four months to research it and I travelled all
>> over the country, visiting engineering companies and suppliers who work at
>> the high-performance end of the business. My report had so many elements
>> in it, it was hard to keep it organized. And it just scratched the surface
>> of the subject.
>
> There is no end of complexity in chemistry. I worked with a guy whose
> specialty was a single effing orbital of the copper atom under specific
> energy conditions..... goodgawd......
>
>>
>> You're right, it is a very complicated subject. If you've ever read the
>> reports on adhesives from the USDA Forest Products Laboratory, you know
>> they're long -- and excellent. And that's just for wood and wood
>> composites. When you get metal and plastics involved, the complexity
>> compounds.
>>
>> That is, if you need high performance. The gummy glues, like contact
>> cement and consumer-grade moisture-cure polyurethanes, solve a hundred
>> different problems very neatly. But that's because most applications only
>> require one or two types of strength -- in their case, it's mostly peel
>> and cleavage, which are the toughest kinds of strength to get, usually,
>> when you're bonding dissimilar materials. Contact cement is not a strong
>> adhesive in engineering terms. But it may well be the strongest, and the
>> best, for your application.
>>
>> So tell us what the application is.
>
> Well, I can't spill ALL the beans..... :) :)
>
> But basically it is a semi-portable jungle-jim-type apparatus, that needs to
> be stabilized by a base, as the user will be pushing/pulling on the
> apparatus, and the user's bodyweight is often what will prevent tipping.
> True, I could make the apparatus itself 1,000# or so, and then I wouldn't
> need a base..... LOL
>
> The base has "guy poles" and gussets to the apparatus itself, so in
> actuality, the base can be surprisingly thin and function pretty well, but
> of course not too thin. I was frankly quite surprised that the 1/2 ply
> works so well.
>
> So there is some flex in the base, on the order of a cupla inches over a 4
> ft to 6 ft dimension, but nothing like a foot.
>
> My laminating jihad here is in lieu of having to finish the ply. Ordinary
> ply (one "good" face), with boucou coats of poly, actually turns out VERY
> nicely, but goddamm, what a pita!! -- and ultimately proly perty costly ito
> production. I'm looking for more of a slam/dunk solution, as well as some
> alternative solutions ito style, interior design, etc.
>
> So dats the overall context. I have some neat solutions for capping the
> edges, etc, which is another story, but which also lends to the rigidity.
> Heh, I could also get away with no adhesive at all, because of how the
> edging is finished, and, if shear is really such a big deal (and would
> destroy the ply over time in the flexing process), then mebbe the solution
> is to omit the adhesive and just live without the additional stiffness of
> unitized members.
>
> We'll see what happens. Heh, you want a unit??
> It's basically the portable version of the stuff I've been building, that I
> offered you once before -- which you graciously declined..... :) :)
> Oh, and for YOU, FREE INSTALLATION!!!!
>
> So how do you resolve the disparate opinion from Tim and Robatoy, ito of
> symmetrical lamination?

Robatoy is telling you how to do it if you're using ordinary stuff that
you might laminate to ply (read: stuff that normal folks normally use),
and that you don't want to warp.

I'm specifically addressing how you might do it if you're laminating
something thats Really Fricking Strong* compared to plywood, and how you
would do it in such a way that nothing actually breaks. In other words
-- I'm having fun trying to figure out what would essentially be an
aviation or similar application, he's trying to tell you how to make
things work right for something much like what you're doing.

I think you want to go with something like melamine or Formica or other
'normal' hard surface for wood, that's not going to lend much strength
to the wood (and hence isn't going to stress the glue too much). Vinyl,
maybe. That'll go on with ordinary contact cement, it'll stretch and
shrink with the wood, and it'll look good.

Make extra special delux units with hardwood veneer and varnish --
charge $$ extra.

* That's an engineering term, by the way.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

>>>>
>>>> Ackshooly, that 13% inc in stiffness presumes similar materials. I
>>>> measured that 1/4" alum plate is as stiff or stiffer than decent 1/2"
>>>> ply, so the increase in stiffness is likely to be a bit more than 13%.
>>> Laminating materials with different Young's modulus is not generally
>>> additive.
>> For 030 aluminum over 1/2" plywood the aluminum is going to carry most of
>> the tensile load from bending.....
>
> Yeah, as long as it's on the tension side....
>
>> ..., which means that (a) the shear load at the
>> aluminum to plywood joint is going to be tremendous, and (b) the assembly
>> is going to be approximately as stiff as a 3/16" plate of aluminum
>> (because the cube root of 9/16 cubed minus 1/2 cubed is about equal to
>> 3/8).
>>
>> At least until the glue joint, or the underlying plywood, gives way.
>> Then it'll be a gawdaful mess.
>
> It doesn't sound like a good idea, does it? I wonder what kind of load EA is
> thinking about, that he's concerned about bending stiffness.
>

No, it actually sounds like a very Bad Idea (tm).

Advice to OP, pick ONE material and use enough of it to handle the load.

And, unless you can match Boeing's aluminum bonding technology, don't.


--

Richard Lamb
http://www.home.earthlink.net/~cavelamb
http://www.home.earthlink.net/~sv_temptress

In article <[email protected]>, [email protected]
says...
>
> "Tim" <[email protected]> wrote in message
> news:[email protected]...
> > On Tue, 12 Jul 2011 01:06:07 -0400, Ed Huntress wrote:
> >
> >> "Tim" <[email protected]> wrote in message
> >> news:[email protected]...
> >>> On Mon, 11 Jul 2011 23:23:50 -0400, Ed Huntress wrote:
> >>>
> >>>> "Existential Angst" <[email protected]> wrote in message
> >>>> news:[email protected]...
> >>>>> Awl --
> >>>>>
> >>>>> Previously (on RW), I asked about coatings, waterproofing plywood.
> >>>>>
> >>>>> Now, in an interior environment (moisture not an issue), I'm curious
> >>>>> about laminating an approx. 4' x 6' area of plywood with some other
> >>>>> thin-ish, or even not so thin-ish material -- from formica laminates,
> >>>>> to .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
> >>>>>
> >>>>> I recall carpenters using gobs of white elmers glue for large-contact
> >>>>> wood areas, in building mezzanines in lofts, etc. Then there is
> >>>>> elmer's carpenter's/wood glue, mastics for tile (what's a mastic,
> >>>>> inyway??), epoxies, a zillion other adhesives.
> >>>>>
> >>>>> The general Q is: when to use what for what?
> >>>>>
> >>>>> For example, in the .030 SS/Alum I will place over 1/2" ply, I would
> >>>>> like to be able to just roll on some suitable adhesive over the full
> >>>>> 4x6 area, and press them together, proly via weight plates. What
> >>>>> would good choices be? How thick?
> >>>>>
> >>>>> Interestingly, an increase in thickness from ..5 to .532 will
> >>>>> generate about a 13% increase in stiffness, since stiffness is
> >>>>> proportional to the square of thickness...
> >>>>
> >>>> Proportional to the *cube* of thickness.
> >>>>
> >>>>> , but ONLY if there is no slippage between the two layers.
> >>>>
> >>>> Correct.
> >>>>
> >>>>> Thus, the requirement for full-surface bonding, via adhesive.
> >>>>>
> >>>>> Ackshooly, that 13% inc in stiffness presumes similar materials. I
> >>>>> measured that 1/4" alum plate is as stiff or stiffer than decent 1/2"
> >>>>> ply, so the increase in stiffness is likely to be a bit more than
> >>>>> 13%.
> >>>>
> >>>> Laminating materials with different Young's modulus is not generally
> >>>> additive.
> >>>
> >>> For 030 aluminum over 1/2" plywood the aluminum is going to carry most
> >>> of the tensile load from bending.....
> >>
> >> Yeah, as long as it's on the tension side....
> >>
> >>>..., which means that (a) the shear load at the
> >>> aluminum to plywood joint is going to be tremendous, and (b) the
> >>> assembly is going to be approximately as stiff as a 3/16" plate of
> >>> aluminum (because the cube root of 9/16 cubed minus 1/2 cubed is about
> >>> equal to 3/8).
> >>>
> >>> At least until the glue joint, or the underlying plywood, gives way.
> >>> Then it'll be a gawdaful mess.
> >>
> >> It doesn't sound like a good idea, does it? I wonder what kind of load
> >> EA is thinking about, that he's concerned about bending stiffness.
> >
> > The plywood would keep the aluminum on the compression side from
> > buckling, for a while. Its kinda like an aluminum honeycomb between
> > solid sheet, with the plywood instead of the honeycomb.
> >
> > If "light and stiff" are what he's looking for, it'd certainly deliver.
> > But when it let go it'd let go with a bang, and there's all sorts of
> > wrong with trying to bond wood to metal.
>
> Christ, idn't ANYTHING simple, anymore??? Sheeesh.....

Not if you're looking for "light and stiff".

If you want something light, stiff, and cheap and easy to make from
readily available materials, use pink foam insulation and bond 1/8"
plywood to each side with a structural-rated adhesive labelled for use
with foam (some structural adhesives use solvents that will dissolve
foam).

Home Depot and Lowes should have everything you need for small panels,
you may have to go to real lumber yard to get 1/8" ply in big panels.

The ply gives you the tension and compression members, the foam carries
the shear between them, and the foam takes glue well.

If you're going to need to put screws into it or bolts through it, cut
out the foam and put some solid wood blocks where the screws or bolts
will go.

For a neat job you can also put solid wood around the edges--pieces
milled from the spruce 2x3s that Home Depot sells work well for this and
are very light.

Don't trust anybody's life to it without making up a sample and testing
to destruction.

In article <[email protected]>, [email protected]
says...
>
> <[email protected]> wrote in message
> news:e264f1cc-fa4d-4af4-b42a-758a0f2d2d4e@m18g2000vbl.googlegroups.com...
> On Jul 11, 8:54 pm, "Existential Angst" <[email protected]> wrote:
> > Awl --
> >
> > Previously (on RW), I asked about coatings, waterproofing plywood.
> >
> > Now, in an interior environment (moisture not an issue), I'm curious about
> > laminating an approx. 4' x 6' area of plywood with some other thin-ish, or
> > even not so thin-ish material -- from formica laminates, to .030 SS or
> > Alum
> > sheet, to 1/4" rubberized tile, linoleum.
> >
> > I recall carpenters using gobs of white elmers glue for large-contact wood
> > areas, in building mezzanines in lofts, etc.
> > Then there is elmer's carpenter's/wood glue, mastics for tile (what's a
> > mastic, inyway??), epoxies, a zillion other adhesives.
> >
> > The general Q is: when to use what for what?
> >
> > For example, in the .030 SS/Alum I will place over 1/2" ply, I would like
> > to
> > be able to just roll on some suitable adhesive over the full 4x6 area, and
> > press them together, proly via weight plates.
> > What would good choices be? How thick?
> >
> > Interestingly, an increase in thickness from ..5 to .532 will generate
> > about
> > a 13% increase in stiffness, since stiffness is proportional to the square
> > of thickness, but ONLY if there is no slippage between the two layers.
> > Thus, the requirement for full-surface bonding, via adhesive.
> >
> > Ackshooly, that 13% inc in stiffness presumes similar materials. I
> > measured
> > that 1/4" alum plate is as stiff or stiffer than decent 1/2" ply, so the
> > increase in stiffness is likely to be a bit more than 13%.
> >
> > Inyway, I'd like an idea of how to gauge the type of adhesive to
> > application. Bang fer the buck is always good, as well.
> >
> > Along these lines, I see all kinds of two-part epoxies, specialized for
> > wood, metal, ceramics/glass, etc.
> > Afaict, they all work the same on everything, with perhaps the exception
> > of
> > things like nylon, delrin, other "greasy" plastics. Any opinions on this?
> > --
> > EA
>
> >If you want stiffness out of wood construction, look up "torsion
> >box". Can be scaled to whatever size you want.
> >I've seen the technique used for cantilevered shelves coming out of
> >walls with no supports.
> >
> >Stan
>
> Torsion boxes are great, but if you follow the whole thread, it sounds like
> he needs something much thinner.

If he wants something fairly stiff, light, and about a half inch thick,
I'd say try bonding some 20" wide flashing to both sides of a piece of
1/2" foam insulation. Use a structural adhesive rated for foam and
aluminum. Point of failure will likely be shear in the foam. Same
caveats as with all foam core--if you need to put screws or bolts
through it, cut out the foam where they go and put in something solid.

And test the Hell out of it before trusting it in a situation in which
someone can get hurt.

On 07/12/2011 12:08 PM, Robatoy wrote:
> On Jul 12, 1:41 pm, Tim Wescott<[email protected]> wrote:
>> On 07/12/2011 10:09 AM, Robatoy wrote:
>>
>>> On Jul 12, 11:12 am, "Existential Angst"<[email protected]> wrote:
>>
>>>> So how do you resolve the disparate opinion from Tim and Robatoy, ito of
>>>> symmetrical lamination?
>>
>>> I can't speak for Tim, but I have laminated elevator panels,
>>> restaurant cabinets, bars, floors, walls, tables, countertops in a
>>> variety of materials, back splashes, suspended ceiling sections,
>>> valences.... I could go on.
>>
>> Like I said, I was specifically addressing the oddball case of
>> laminating aluminum to plywood.
>
> Laminating aluminum, clear, brushed, shiny comes in many diffent
> sheens, and is already prepped for laminating.
> Just about anybody sells that stuff, Wilsonart, Formica, Arborite,
> Nevamar.

But is it load bearing? Can you laminate it onto plywood, then actually
use the strength of the aluminum?

Or is it just a way to make it shiny?

>> It makes a really interesting
>> theoretical problem, and may even be practical for a homebuilt airplane,
>> if you need the strength and you're a hot-shit adhesive engineer, and
>> you keep it dry.
>>
>> But it's not what EA wants.
>>
>
> Yea.... what DOES he want? LOL
>


--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

On 07/12/2011 08:14 AM, Ed Huntress wrote:
> "Existential Angst"<[email protected]> wrote in message
> news:[email protected]...
>> "Ed Huntress"<[email protected]> wrote in message
>> news:[email protected]...
>>>
>>> "Existential Angst"<[email protected]> wrote in message
>>> news:[email protected]...
>>>> "Tim"<[email protected]> wrote in message
>>>> news:[email protected]...
>>>>> On Tue, 12 Jul 2011 07:13:44 -0400, dadiOH wrote:
>>>>>
>>>>>> Existential Angst wrote:
>>>>>>> Awl --
>>>>>>>
>>>>>>> Previously (on RW), I asked about coatings, waterproofing plywood.
>>>>>>>
>>>>>>> Now, in an interior environment (moisture not an issue), I'm curious
>>>>>>> about laminating an approx. 4' x 6' area of plywood with some other
>>>>>>> thin-ish, or even not so thin-ish material -- from formica laminates,
>>>>>>> to .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>>>>>>>
>>>>>>> I recall carpenters using gobs of white elmers glue for large-contact
>>>>>>> wood areas, in building mezzanines in lofts, etc. Then there is
>>>>>>> elmer's
>>>>>>> carpenter's/wood glue, mastics for tile (what's a mastic, inyway??),
>>>>>>> epoxies, a zillion other adhesives.
>>>>>>
>>>>>> Mastic is a pasty material. Like linoleum paste...Liquid Nails...etc.
>>>>>> __________________
>>>>>>
>>>>>>> The general Q is: when to use what for what?
>>>>>>
>>>>>> http://www.thistothat.com/
>>>>>>
>>>>>> For most of the things you mentioned, contact cement.
>>>>>> _________________
>>>>>
>>>>> Contact cement would, I think, work well for 030 aluminum to one side
>>>>> of
>>>>> 1/4 plywood, where the wood would have a chance to flex. It may work
>>>>> on
>>>>> 1/2" plywood if the bond isn't heavily stressed.
>>>>
>>>> You're saying the bond would be less stressed with thinner ply than
>>>> thicker??
>>>> That seems counter-intuitive!
>>>
>>> Tim is right.
>>
>> Because there's less distance to the neutral axis?
>
> No, because the force is a product of the volume of the material that's
> trying to stretch or shrink, and thicker material exerts more force.

I dunno -- I was seeing it as the distance from the neutral axis. You
can't increase the distance from the neutral axis without increasing
volume, so they pretty much go together.

I was saying that if you only put the aluminum on _one side_, _and_ you
use something thinner than 1/2 inch, that you should be OK. Basically,
the aluminum is going to move a lot less than the wood. Only doing one
side gives the wood an opportunity to move (and to bow with humidity),
which relieves stress on the glue joint.

Put Al on both sides of the wood and you're right back to gluing a
strong thing to a weak thing with stuff of questionable strength -- so
if you stress it to breaking, either the glue bond or the underlying
wood is going to shear, or the glue on the compression side is going to
let the aluminum lift and buckle, or the wood on the compression side is
going to let the aluminum dig in and buckle.

But (again) if rigidity is more important than strength, this may not be
a bad way to go.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

On Jul 11, 8:54=A0pm, "Existential Angst" <[email protected]> wrote:
> Awl --
>
> Previously (on RW), I asked about coatings, waterproofing plywood.
>
> Now, in an interior environment (moisture not an issue), I'm curious abou=
t
> laminating an approx. 4' x 6' area of plywood with some other thin-ish, o=
r
> even not so thin-ish material -- from formica laminates, to .030 SS or Al=
um
> sheet, to 1/4" rubberized tile, linoleum.
>
> I recall carpenters using gobs of white elmers glue for large-contact woo=
d
> areas, in building mezzanines in lofts, etc.
> Then there is elmer's carpenter's/wood glue, mastics for tile (what's a
> mastic, inyway??), epoxies, a zillion other adhesives.
>
> The general Q is: =A0when to use what for what?
>
> For example, in the .030 SS/Alum I will place over 1/2" ply, I would like=
to
> be able to just roll on some suitable adhesive over the full 4x6 area, an=
d
> press them together, proly via weight plates.
> What would good choices be? =A0How thick?
>
> Interestingly, an increase in thickness from ..5 to .532 will generate ab=
out
> a 13% increase in stiffness, since stiffness is proportional to the squar=
e
> of thickness, but ONLY if there is no slippage between the two layers.
> Thus, the requirement for full-surface bonding, via adhesive.
>
> Ackshooly, that 13% inc in stiffness presumes similar materials. =A0I mea=
sured
> that 1/4" alum plate is as stiff or stiffer than decent 1/2" ply, so the
> increase in stiffness is likely to be a bit more than 13%.
>
> Inyway, I'd like an idea of how to gauge the type of adhesive to
> application. =A0Bang fer the buck is always good, as well.
>
> Along these lines, I see all kinds of two-part epoxies, specialized for
> wood, metal, ceramics/glass, etc.
> Afaict, they all work the same on everything, with perhaps the exception =
of
> things like nylon, delrin, other "greasy" plastics. =A0Any opinions on th=
is?
> --
> EA

If you want stiffness out of wood construction, look up "torsion
box". Can be scaled to whatever size you want.
I've seen the technique used for cantilevered shelves coming out of
walls with no supports.

Stan

On Jul 11, 10:54=A0pm, "Existential Angst" <[email protected]> wrote:

> =A0Any opinions on this?

Yes. Many opinions. Just make sure that when laminating dissimilar
materials, to do both sides of the substrate, a 'balance' sheet.
Trying to get away without one is foolish. In case of laminate, just a
cheap discontinued colour will suffice.
Also, look into Wilsonart 3000 adhesive. Water based, will stick
anything to anything (other than greasy plastics).
Lots of open time and a decent roller which will allow your body
weight to do the work is all you need.
Wilsonart 3000 is NOT contact cement but works a bit like it. One side
of the joint has to have minimal porosity.

On Jul 12, 1:41=A0pm, Tim Wescott <[email protected]> wrote:
> On 07/12/2011 10:09 AM, Robatoy wrote:
>
> > On Jul 12, 11:12 am, "Existential Angst"<[email protected]> =A0wrote=
:
>
> >> So how do you resolve the disparate opinion from Tim and Robatoy, ito =
of
> >> symmetrical lamination?
>
> > I can't speak for Tim, but I have laminated elevator panels,
> > restaurant cabinets, bars, floors, walls, tables, countertops in a
> > variety of materials, back splashes, suspended ceiling sections,
> > valences.... I could go on.
>
> Like I said, I was specifically addressing the oddball case of
> laminating aluminum to plywood.

Laminating aluminum, clear, brushed, shiny comes in many diffent
sheens, and is already prepped for laminating.
Just about anybody sells that stuff, Wilsonart, Formica, Arborite,
Nevamar.

> It makes a really interesting
> theoretical problem, and may even be practical for a homebuilt airplane,
> if you need the strength and you're a hot-shit adhesive engineer, and
> you keep it dry.
>
> But it's not what EA wants.
>

Yea.... what DOES he want? LOL

On Jul 12, 1:11=A0pm, "J. Clarke" <[email protected]> wrote:
> In article <[email protected]>, [email protected]
> says...
>
>
>
>
>
>
>
> > <[email protected]> wrote in message
> >news:e264f1cc-fa4d-4af4-b42a-758a0f2d2d4e@m18g2000vbl.googlegroups.com..=
.
> > On Jul 11, 8:54 pm, "Existential Angst" <[email protected]> wrote:
> > > Awl --
>
> > > Previously (on RW), I asked about coatings, waterproofing plywood.
>
> > > Now, in an interior environment (moisture not an issue), I'm curious =
about
> > > laminating an approx. 4' x 6' area of plywood with some other thin-is=
h, or
> > > even not so thin-ish material -- from formica laminates, to .030 SS o=
r
> > > Alum
> > > sheet, to 1/4" rubberized tile, linoleum.
>
> > > I recall carpenters using gobs of white elmers glue for large-contact=
wood
> > > areas, in building mezzanines in lofts, etc.
> > > Then there is elmer's carpenter's/wood glue, mastics for tile (what's=
a
> > > mastic, inyway??), epoxies, a zillion other adhesives.
>
> > > The general Q is: when to use what for what?
>
> > > For example, in the .030 SS/Alum I will place over 1/2" ply, I would =
like
> > > to
> > > be able to just roll on some suitable adhesive over the full 4x6 area=
, and
> > > press them together, proly via weight plates.
> > > What would good choices be? How thick?
>
> > > Interestingly, an increase in thickness from ..5 to .532 will generat=
e
> > > about
> > > a 13% increase in stiffness, since stiffness is proportional to the s=
quare
> > > of thickness, but ONLY if there is no slippage between the two layers=
.
> > > Thus, the requirement for full-surface bonding, via adhesive.
>
> > > Ackshooly, that 13% inc in stiffness presumes similar materials. I
> > > measured
> > > that 1/4" alum plate is as stiff or stiffer than decent 1/2" ply, so =
the
> > > increase in stiffness is likely to be a bit more than 13%.
>
> > > Inyway, I'd like an idea of how to gauge the type of adhesive to
> > > application. Bang fer the buck is always good, as well.
>
> > > Along these lines, I see all kinds of two-part epoxies, specialized f=
or
> > > wood, metal, ceramics/glass, etc.
> > > Afaict, they all work the same on everything, with perhaps the except=
ion
> > > of
> > > things like nylon, delrin, other "greasy" plastics. Any opinions on t=
his?
> > > --
> > > EA
>
> > >If you want stiffness out of wood construction, look up "torsion
> > >box". =A0Can be scaled to whatever size you want.
> > >I've seen the technique used for cantilevered shelves coming out of
> > >walls with no supports.
>
> > >Stan
>
> > Torsion boxes are great, but if you follow the whole thread, it sounds =
like
> > he needs something much thinner.
>
> If he wants something fairly stiff, light, and about a half inch thick,
> I'd say try bonding some 20" wide flashing to both sides of a piece of
> 1/2" foam insulation. =A0Use a structural adhesive rated for foam and
> aluminum. =A0Point of failure will likely be shear in the foam. =A0Same
> caveats as with all foam core--if you need to put screws or bolts
> through it, cut out the foam where they go and put in something solid.
>
> And test the Hell out of it before trusting it in a situation in which
> someone can get hurt.

Virtually NO impact resistance... maybe some in blunt impact...but...

Existential Angst wrote:
> Awl --
>
> Previously (on RW), I asked about coatings, waterproofing plywood.
>
> Now, in an interior environment (moisture not an issue), I'm curious
> about laminating an approx. 4' x 6' area of plywood with some other
> thin-ish, or even not so thin-ish material -- from formica laminates,
> to .030 SS or Alum sheet, to 1/4" rubberized tile, linoleum.
>
> I recall carpenters using gobs of white elmers glue for large-contact
> wood areas, in building mezzanines in lofts, etc.
> Then there is elmer's carpenter's/wood glue, mastics for tile (what's
> a mastic, inyway??), epoxies, a zillion other adhesives.

Mastic is a pasty material. Like linoleum paste...Liquid Nails...etc.
__________________

> The general Q is: when to use what for what?

http://www.thistothat.com/

For most of the things you mentioned, contact cement.
_________________

--

dadiOH
____________________________

dadiOH's dandies v3.06...
...a help file of info about MP3s, recording from
LP/cassette and tips & tricks on this and that.
Get it at http://mysite.verizon.net/xico

Existential Angst wrote:
> "dadiOH" <[email protected]> wrote in message
> news:[email protected]...
>> Existential Angst wrote:
>>> Awl --
>>>
>>> Previously (on RW), I asked about coatings, waterproofing plywood.
>>>
>>> Now, in an interior environment (moisture not an issue), I'm curious
>>> about laminating an approx. 4' x 6' area of plywood with some other
>>> thin-ish, or even not so thin-ish material -- from formica
>>> laminates, to .030 SS or Alum sheet, to 1/4" rubberized tile,
>>> linoleum. I recall carpenters using gobs of white elmers glue for
>>> large-contact wood areas, in building mezzanines in lofts, etc.
>>> Then there is elmer's carpenter's/wood glue, mastics for tile
>>> (what's a mastic, inyway??), epoxies, a zillion other adhesives.
>>
>> Mastic is a pasty material. Like linoleum paste...Liquid
>> Nails...etc. __________________
>>
>>> The general Q is: when to use what for what?
>>
>> http://www.thistothat.com/
>
> Very inneresting site, lots of upside potential with that site, that I
> emailed them about.
>
>
>>
>> For most of the things you mentioned, contact cement.
>
> So it seems!!!


Contact cement is hard to apply evenly and is messy: plan on throwing away
any roller/brush used for application. Porous surfaces will most likely
require two coats. Each surface needs to look glossy all over and must be
dry enough so your finger doesn't stick.

Others have suggested using paper slip sheets. That will work but the thing
about contact cement is, well, it bonds on contact. I prefer to use dowels
or sticks to keep the two surfaces well apart from each other until you are
ready to bond them. I usually space them (dowels) 12-15" apart, depends on
the dowel diameter.

Once you start bonding, start at the center and work out toward the ends to
avoid trapping air. Once all is bonded it needs to be *BONDED*. Do that
with a J-roller, lots of pressure; again, work from center out to the ends
and edges. You can also use a rubber mallet, roller is better.


--

dadiOH
____________________________

dadiOH's dandies v3.06...
...a help file of info about MP3s, recording from
LP/cassette and tips & tricks on this and that.
Get it at http://mysite.verizon.net/xico