Hi,
I'm wondering if someone knows the actual numbers on glue
strength? (i.e., strength per unit of surface)
I'm talking about the plastic glue (yellow or white -- I
think it's vynil-based), assuming that it is used to glue
two pieces of very-flat very-clean along-the-grain wood
surfaces, with no gap between the surfaces of more than
1/200" or so. At least typical values, or worst-case
values (if it depends on the wood, or on the angle of
the surface with respect to the grain, etc.)
A google search on this newsgroup returns nothing; the
specs of the glue (both on its label and on Lepage's web
site) only include the catchy advertising phrase "bonds
with 2 tons of strength" (GOD, such idiots!! Only for
that I shouldn't buy anything from them!!! :-( such
flashbacks of infomertials advertising crap), so I'm at
a loss.
Anyway, I'll be grateful for any info!
Thanks,
Carlos
--
<snip>
> > piece of 13/16" soft maple. I ripped it in half and jointed the dges. I
> > used Lee Valley glue and rubbed the two edges together to make sure that I
> > had a joint that was evenly coated. I took 3 pipe clamps and used a pipe
> > wrench on the handles. The clamps left very nice depressions in the
> > outside of the boards.
<snip>
From all the research that I have read, the strength of the joint is
not directly proportional to the clamp pressure applied. Certainly
using a pipe wrench to tighten a clamp is overkill.
Normal hand pressure (or even less) is probably best if a nice thin
coat of glue is applied to both surfaces.
OTOH, I have not mastered this either and learn with every new project.
Lou
I was interested so I went down to the shop and took a 12" long X 10" wide
piece of 13/16" soft maple. I ripped it in half and jointed the dges. I
used Lee Valley glue and rubbed the two edges together to make sure that I
had a joint that was evenly coated. I took 3 pipe clamps and used a pipe
wrench on the handles. The clamps left very nice depressions in the outside
of the boards.
I let the glue cure overnight and put the piece in my vise. I used a
ribber mallet and beat the board until it finally broke. It did not break
along the glue joint. One sample does not prove the issue but I was not able
to produce a starved glue joint even with 1 clamp every 5 inches or so (1
clamp 1" in from each and and one clamp in the middle).
A more scientific experiment would involve using a hydraulic press on
small (1" X 1") samples.
--
dbchamber at hotmail spam dot com
Remove the spam to reach me
"David" <[email protected]> wrote in message
news:[email protected]...
> :) I hear you George. We all have our opinions and nobody is going to
> change them. I'm not closed minded enough to refuse to learn "new
> tricks".
>
> David
>
> George wrote:
>> Why bother? They're probably as closed-minded as you are. Mine's by
>> experience, can't change that.
>>
>> "David" <[email protected]> wrote in message
>> news:[email protected]...
>>
>>>Talk to the folks at Franklin. Tell them they don't know their business.
>>>
>>>David
>>>
>>>David
>>>
>>>George wrote:
>>>
>>>
>>>>If you apply clamping pressure immediately and excessively, you will
>>
>> squeeze
>>
>>>>so much out that you can actually break on the glue line after cure,
>>>>especially on woods like hard maple which don't soak much. It's NOT a
>>
>> myth
>>
>>>>to an Industrial Arts teacher who's seen what teenage males can do to
>>
>> pipe
>>
>>>>clamps....
>>>>
>>>>"David" <[email protected]> wrote in message
>>>>news:[email protected]...
>>>>
>>>>
>>>>>Yeah, like going swimming within 1 hour of eating will cause drowning
>>>>
>>>>>from cramps. You are repeating a myth.
>>>>
>>>>>David
>>>>>
>>>>>[email protected] wrote:
>>>>>
>>>>>
>>>>>>>Sbtypesetter wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>* Clamping pressures are much lower
>>>>>>>>than most every woodworker uses. Too
>>>>>>>>much pressure will result in a starved
>>>>>>>>joint.
>>>>>>
>>>>>>
>>>>>>
>>>>>>On Thu, 04 Nov 2004 11:58:48 -0800, David <[email protected]> wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>Not so sure I agree with the "starved joint" syndrome, merely from
>>>>>>>the
>>>>>>>application of "too much" clamping pressure. Damaged wood fibers can
>>>>>>>result from behemoth pressures, but more likely a "starved" joint is
>>
>> due
>>
>>>>>>>to insufficient glue applied BEFORE clamping the joint, as opposed to
>>>>>>>the pressure of the clamping being the culprit.
>>>>>>>
>>>>>>>David
>>>>>>>
>>>>>>
>>>>>>
>>>>>>overclamping can starve the joint.
>>>>
>>>>
>>>>
>>
The LMI catalog had a short note on glue
strength a few years back. I cwn't even
begin to recall the numbers but I can
say this much.
* Shelf life will improve if kept in the
refrigerator.
* Shelf life is much shorter than you
might suspect.
* LMI offers a yellow glue with about
double the strength of off-the-shelf
yellow glue. The price is much higher
and when kept cool the shelf life is only
about six months.
* Yellow glue is non gap filling. The
strength comes from infusing the pores
of the wood. Therefore the wood needs
a smooth finish but not burnished as this
will inhibit absorption.
* You are correct on a gap of 1/200th inch.
* Clamping pressures are much lower
than most every woodworker uses. Too
much pressure will result in a starved
joint.
* A perfect joint is much more important
than one mught suspect. Never clamp
tight to close a joint. Some sections of
the joint will be starved, other just right,
and other gap filled. Take the time to
get the joint right.
*Regular yellow glue (A.R.G.?) is usually
stronger than the wood being joined.
That about exhausts my knowledge.
Hope I was of some help.
-Rick Buchanan
On Tue, 09 Nov 2004 00:06:16 GMT, "George E. Cawthon"
<[email protected]> wrote:
<snip>
>>
>> What a pleasant way to say "Our glue will hold with little or no
>> clamping pressure if you guys would get your shit together and make
>> tight joints with straight wood... lol
>>
>> Thanks for posting that... it is good info and a reminder to not blame
>> the glue for my poor workmanship and to be more diligent in learning
>> good joinery..
>
>Actually, what he said was quite different and positive not negative,
>"Our glue will hold if you bring the joints together, either with
>perfect jointing which then requires little pressure or with imperfect
>jointing which requires whatever pressure is needed to squeeze glue
>out along the entire length of the joint."
That was my point, George... that it was a very positive piece...
Must be all those years in sales fermenting my brian, but I just
appreciate how he stated it in such a positive manner...
Wed, Nov 3, 2004, 11:45pm [email protected]
(Carlos=A0Moreno) mumbled:
Hi,
I'm wondering if someone knows the actual numbers on glue strength?
(i.e., strength per unit of surface) <snip>
In any practical applications, it doesn't matter, they're all
stronger than the wood.
JOAT
When you choose an action, you choose the consequences.
- Unknown
>Sbtypesetter wrote:
>
>> * Clamping pressures are much lower
>> than most every woodworker uses. Too
>> much pressure will result in a starved
>> joint.
On Thu, 04 Nov 2004 11:58:48 -0800, David <[email protected]> wrote:
>Not so sure I agree with the "starved joint" syndrome, merely from the
>application of "too much" clamping pressure. Damaged wood fibers can
>result from behemoth pressures, but more likely a "starved" joint is due
>to insufficient glue applied BEFORE clamping the joint, as opposed to
>the pressure of the clamping being the culprit.
>
>David
>
overclamping can starve the joint.
Enough to know that the glue adheres to itself with greater strength than
the wood has along the grain. Unless, of course you don't spread or clamp
properly. The rest is hype for woodworkers, because the material is too
variable for precise data to be meaningful.
"Carlos Moreno" <[email protected]> wrote in message
news:[email protected]...
>
> Hi,
>
> I'm wondering if someone knows the actual numbers on glue
> strength? (i.e., strength per unit of surface)
>
> I'm talking about the plastic glue (yellow or white -- I
> think it's vynil-based), assuming that it is used to glue
> two pieces of very-flat very-clean along-the-grain wood
> surfaces, with no gap between the surfaces of more than
> 1/200" or so. At least typical values, or worst-case
> values (if it depends on the wood, or on the angle of
> the surface with respect to the grain, etc.)
>
> A google search on this newsgroup returns nothing; the
> specs of the glue (both on its label and on Lepage's web
> site) only include the catchy advertising phrase "bonds
> with 2 tons of strength" (GOD, such idiots!! Only for
> that I shouldn't buy anything from them!!! :-( such
> flashbacks of infomertials advertising crap), so I'm at
> a loss.
>
> Anyway, I'll be grateful for any info!
>
> Thanks,
>
> Carlos
> --
If you apply clamping pressure immediately and excessively, you will squeeze
so much out that you can actually break on the glue line after cure,
especially on woods like hard maple which don't soak much. It's NOT a myth
to an Industrial Arts teacher who's seen what teenage males can do to pipe
clamps....
"David" <[email protected]> wrote in message
news:[email protected]...
> Yeah, like going swimming within 1 hour of eating will cause drowning
> from cramps. You are repeating a myth.
>
> David
>
> [email protected] wrote:
> >>Sbtypesetter wrote:
> >>
> >>
> >>>* Clamping pressures are much lower
> >>> than most every woodworker uses. Too
> >>> much pressure will result in a starved
> >>> joint.
> >
> >
> >
> > On Thu, 04 Nov 2004 11:58:48 -0800, David <[email protected]> wrote:
> >
> >
> >>Not so sure I agree with the "starved joint" syndrome, merely from the
> >>application of "too much" clamping pressure. Damaged wood fibers can
> >>result from behemoth pressures, but more likely a "starved" joint is due
> >>to insufficient glue applied BEFORE clamping the joint, as opposed to
> >>the pressure of the clamping being the culprit.
> >>
> >>David
> >>
> >
> >
> > overclamping can starve the joint.
Why bother? They're probably as closed-minded as you are. Mine's by
experience, can't change that.
"David" <[email protected]> wrote in message
news:[email protected]...
> Talk to the folks at Franklin. Tell them they don't know their business.
>
> David
>
> David
>
> George wrote:
>
> > If you apply clamping pressure immediately and excessively, you will
squeeze
> > so much out that you can actually break on the glue line after cure,
> > especially on woods like hard maple which don't soak much. It's NOT a
myth
> > to an Industrial Arts teacher who's seen what teenage males can do to
pipe
> > clamps....
> >
> > "David" <[email protected]> wrote in message
> > news:[email protected]...
> >
> >>Yeah, like going swimming within 1 hour of eating will cause drowning
> >>from cramps. You are repeating a myth.
> >>
> >>David
> >>
> >>[email protected] wrote:
> >>
> >>>>Sbtypesetter wrote:
> >>>>
> >>>>
> >>>>
> >>>>>* Clamping pressures are much lower
> >>>>> than most every woodworker uses. Too
> >>>>> much pressure will result in a starved
> >>>>> joint.
> >>>
> >>>
> >>>
> >>>On Thu, 04 Nov 2004 11:58:48 -0800, David <[email protected]> wrote:
> >>>
> >>>
> >>>
> >>>>Not so sure I agree with the "starved joint" syndrome, merely from the
> >>>>application of "too much" clamping pressure. Damaged wood fibers can
> >>>>result from behemoth pressures, but more likely a "starved" joint is
due
> >>>>to insufficient glue applied BEFORE clamping the joint, as opposed to
> >>>>the pressure of the clamping being the culprit.
> >>>>
> >>>>David
> >>>>
> >>>
> >>>
> >>>overclamping can starve the joint.
> >
> >
> >
mac davis wrote:
>
> On 8 Nov 2004 08:09:14 -0600, jev <[email protected]> wrote:
> >Attached is the text of message from Franklin - makers of titebond. This msg was originally posted to this forum and am sorry i can't credit the original poster.
> >Response from Frnklain/Titebond rep re:Calmping Pressure
> >
> >I am writing in response to your question about clamp pressure.
> >First, your calculation and understanding is correct. If you wanted
> >to produce 200 psi over an area 12" x 12", you would need 28,800
> >pounds of force. On the other hand, it is not clear whether you
> >often, or ever, fell short of the actual, required clamp pressure.
> >
> >The actual required clamp pressure for any bond involving a wood glue
> >is a combination of the small amount of pressure required to squeeze
> >the glue into a thin, consistent layer, and the pressure necessary the
> >compensate for any distortion or lack of fit in the wood stock being
> >used. That means when the surfaces of the pieces being joined are
> >true, and there is no gap between the pieces when they are dry fit,
> >very little pressure is required. If, however, the same assembly is
> >being made using pieces which are bowed, twisted or ill-fitted, the
> >required pressure is much greater, and is largely the pressure
> >required to straighten the wood and pull it into position. Thus, the
> >actual required pressure for a bond also reflects the thickness, or
> >fight, of the wood involved, with much more pressure obviously
> >required to straighten a very thick piece of maple or oak than to
> >straighten a thinner piece of the same species.
> >
> >In many applications, then, pressure, serves to compensate for some
> >lack of diligence in wood preparation. That being the case, good wood
> >preparation lessens the need for, or dependence on, pressure. In the
> >case of our literature, the high suggested pressures reflect the fact
> >that those individuals being addressed include those who, at least on
> >occasion, are trying to bond thick, poorly fitted pieces of wood, and
> >for those readers, the high, suggested values are, indeed, necessary.
> >
> >Finally, because the bond strength produced in a joint is the result
> >of the entanglement of the glue particles which have been drawn into
> >the pores and anchored to the wood on the two sides of the joint,
> >there is rarely any concern for applying so much pressure that the
> >glue is all squeezed out.
> >
> >In fact, the bond strength achieved increases as the bondline or layer
> >of glue becomes thinner. Given that fact, there are only two
> >situations in which high pressures may be counterproductive. First,
> >there is always a concern that the pores of wood at the bonding
> >surfaces not be crushed, and that is the reason that our listed
> >pressures are lower for the softer woods. The second situation deals
> >with bonds involving end grain or other open grain. There the concern
> >is that the open grain is prone to suck up a large amount of glue and,
> >if that thirst has not been quenched before clamping, that excessive
> >absorption of glue may result in a starved, and weak joint. Because
> >most bonds involve face or edge grain which is relatively straight,
> >that particular risk is rarely a concern.
>
> What a pleasant way to say "Our glue will hold with little or no
> clamping pressure if you guys would get your shit together and make
> tight joints with straight wood... lol
>
> Thanks for posting that... it is good info and a reminder to not blame
> the glue for my poor workmanship and to be more diligent in learning
> good joinery..
Actually, what he said was quite different and positive not negative,
"Our glue will hold if you bring the joints together, either with
perfect jointing which then requires little pressure or with imperfect
jointing which requires whatever pressure is needed to squeeze glue
out along the entire length of the joint."
Talk to the folks at Franklin. Tell them they don't know their business.
David
David
George wrote:
> If you apply clamping pressure immediately and excessively, you will squeeze
> so much out that you can actually break on the glue line after cure,
> especially on woods like hard maple which don't soak much. It's NOT a myth
> to an Industrial Arts teacher who's seen what teenage males can do to pipe
> clamps....
>
> "David" <[email protected]> wrote in message
> news:[email protected]...
>
>>Yeah, like going swimming within 1 hour of eating will cause drowning
>>from cramps. You are repeating a myth.
>>
>>David
>>
>>[email protected] wrote:
>>
>>>>Sbtypesetter wrote:
>>>>
>>>>
>>>>
>>>>>* Clamping pressures are much lower
>>>>> than most every woodworker uses. Too
>>>>> much pressure will result in a starved
>>>>> joint.
>>>
>>>
>>>
>>>On Thu, 04 Nov 2004 11:58:48 -0800, David <[email protected]> wrote:
>>>
>>>
>>>
>>>>Not so sure I agree with the "starved joint" syndrome, merely from the
>>>>application of "too much" clamping pressure. Damaged wood fibers can
>>>>result from behemoth pressures, but more likely a "starved" joint is due
>>>>to insufficient glue applied BEFORE clamping the joint, as opposed to
>>>>the pressure of the clamping being the culprit.
>>>>
>>>>David
>>>>
>>>
>>>
>>>overclamping can starve the joint.
>
>
>
Yeah, like going swimming within 1 hour of eating will cause drowning
from cramps. You are repeating a myth.
David
[email protected] wrote:
>>Sbtypesetter wrote:
>>
>>
>>>* Clamping pressures are much lower
>>> than most every woodworker uses. Too
>>> much pressure will result in a starved
>>> joint.
>
>
>
> On Thu, 04 Nov 2004 11:58:48 -0800, David <[email protected]> wrote:
>
>
>>Not so sure I agree with the "starved joint" syndrome, merely from the
>>application of "too much" clamping pressure. Damaged wood fibers can
>>result from behemoth pressures, but more likely a "starved" joint is due
>>to insufficient glue applied BEFORE clamping the joint, as opposed to
>>the pressure of the clamping being the culprit.
>>
>>David
>>
>
>
> overclamping can starve the joint.
:) I hear you George. We all have our opinions and nobody is going to
change them. I'm not closed minded enough to refuse to learn "new tricks".
David
George wrote:
> Why bother? They're probably as closed-minded as you are. Mine's by
> experience, can't change that.
>
> "David" <[email protected]> wrote in message
> news:[email protected]...
>
>>Talk to the folks at Franklin. Tell them they don't know their business.
>>
>>David
>>
>>David
>>
>>George wrote:
>>
>>
>>>If you apply clamping pressure immediately and excessively, you will
>
> squeeze
>
>>>so much out that you can actually break on the glue line after cure,
>>>especially on woods like hard maple which don't soak much. It's NOT a
>
> myth
>
>>>to an Industrial Arts teacher who's seen what teenage males can do to
>
> pipe
>
>>>clamps....
>>>
>>>"David" <[email protected]> wrote in message
>>>news:[email protected]...
>>>
>>>
>>>>Yeah, like going swimming within 1 hour of eating will cause drowning
>>>
>>>>from cramps. You are repeating a myth.
>>>
>>>>David
>>>>
>>>>[email protected] wrote:
>>>>
>>>>
>>>>>>Sbtypesetter wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>* Clamping pressures are much lower
>>>>>>>than most every woodworker uses. Too
>>>>>>>much pressure will result in a starved
>>>>>>>joint.
>>>>>
>>>>>
>>>>>
>>>>>On Thu, 04 Nov 2004 11:58:48 -0800, David <[email protected]> wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>Not so sure I agree with the "starved joint" syndrome, merely from the
>>>>>>application of "too much" clamping pressure. Damaged wood fibers can
>>>>>>result from behemoth pressures, but more likely a "starved" joint is
>
> due
>
>>>>>>to insufficient glue applied BEFORE clamping the joint, as opposed to
>>>>>>the pressure of the clamping being the culprit.
>>>>>>
>>>>>>David
>>>>>>
>>>>>
>>>>>
>>>>>overclamping can starve the joint.
>>>
>>>
>>>
>
>
Soft maple is more porous that other woods. Hardwoods with little or no
surface texture don't glue as well as woods like pine and mahogany. Also, 1
inch samples are not a great test because the short length of straight grain
doesn't offer the board as much support and it will be more likely to split
along the grain lines.
WE would occasionally test glue strength by gluing up 3 or 4 strips into a
top. The strips were 3 or 4 inches wide and 12 to 24 inches long. We then
would put a strip at each edge raising it up off the bench and hit the
center of the board until it split. Sometimes the glue joints failed if it
was too cold in the shop when we glued it up.
There are a lot of variables to an objective test.
max
> I was interested so I went down to the shop and took a 12" long X 10" wide
> piece of 13/16" soft maple. I ripped it in half and jointed the dges. I
> used Lee Valley glue and rubbed the two edges together to make sure that I
> had a joint that was evenly coated. I took 3 pipe clamps and used a pipe
> wrench on the handles. The clamps left very nice depressions in the outside
> of the boards.
>
> I let the glue cure overnight and put the piece in my vise. I used a
> ribber mallet and beat the board until it finally broke. It did not break
> along the glue joint. One sample does not prove the issue but I was not able
> to produce a starved glue joint even with 1 clamp every 5 inches or so (1
> clamp 1" in from each and and one clamp in the middle).
>
> A more scientific experiment would involve using a hydraulic press on
> small (1" X 1") samples.
>
"Sbtypesetter" <[email protected]> wrote in message
news:[email protected]...
> * Clamping pressures are much lower
> than most every woodworker uses.
True but,
> Too much pressure will result in a starved
> joint.
The jury is still out on this one as it has not been prooven either way.
Apparently many people that clamp too hard are trying to close a gap and as
indicated, yellow glues do not fill gaps well. I have never had a joint
fail whether I clamped agressively or not. I choose moderate clamping
pressure now.
George wrote:
> Enough to know that the glue adheres to itself with greater strength than
> the wood has along the grain. Unless, of course you don't spread or clamp
> properly. The rest is hype for woodworkers, because the material is too
> variable for precise data to be meaningful.
Thanks to all that replied.
Yes, I guess this is the bottom line -- and I did know it;
it was partly curiosity to know the numbers. I remember
our teacher (in an introductory woodworking course I took)
mentioned the actual number, and he did a demonstration;
he glued together a couple of pieces by their edges, and
then fixed it, took a hammer, and invited us to try and
break it -- naturally, the piece kept breaking anywhere
except at the glued surface!
Thanks,
Carlos
--
Check out www.titebond.com. They have the PSI ratings for their glues.
David
Carlos Moreno wrote:
>
> Hi,
>
> I'm wondering if someone knows the actual numbers on glue
> strength? (i.e., strength per unit of surface)
>
> I'm talking about the plastic glue (yellow or white -- I
> think it's vynil-based), assuming that it is used to glue
> two pieces of very-flat very-clean along-the-grain wood
> surfaces, with no gap between the surfaces of more than
> 1/200" or so. At least typical values, or worst-case
> values (if it depends on the wood, or on the angle of
> the surface with respect to the grain, etc.)
>
> A google search on this newsgroup returns nothing; the
> specs of the glue (both on its label and on Lepage's web
> site) only include the catchy advertising phrase "bonds
> with 2 tons of strength" (GOD, such idiots!! Only for
> that I shouldn't buy anything from them!!! :-( such
> flashbacks of infomertials advertising crap), so I'm at
> a loss.
>
> Anyway, I'll be grateful for any info!
>
> Thanks,
>
> Carlos
> --
The starved glue joint is a myth. The important part of the glue is the
part that soaks into the wood. I suppose if you could squeeze any
excess glue out before it had a chance to soak in a significant amount
maybe you could "starve" the joint. At a normal working pace, plenty of
glue gets into the wood and the thicker the layer between the two pieces
of wood, the weaker the joint. IMHO.
bob g.
David Chamberlain wrote:
> I was interested so I went down to the shop and took a 12" long X 10" wide
> piece of 13/16" soft maple. I ripped it in half and jointed the dges. I
> used Lee Valley glue and rubbed the two edges together to make sure that I
> had a joint that was evenly coated. I took 3 pipe clamps and used a pipe
> wrench on the handles. The clamps left very nice depressions in the outside
> of the boards.
>
> I let the glue cure overnight and put the piece in my vise. I used a
> ribber mallet and beat the board until it finally broke. It did not break
> along the glue joint. One sample does not prove the issue but I was not able
> to produce a starved glue joint even with 1 clamp every 5 inches or so (1
> clamp 1" in from each and and one clamp in the middle).
>
> A more scientific experiment would involve using a hydraulic press on
> small (1" X 1") samples.
>
>
On 8 Nov 2004 08:09:14 -0600, jev <[email protected]> wrote:
>Attached is the text of message from Franklin - makers of titebond. This msg was originally posted to this forum and am sorry i can't credit the original poster.
>Response from Frnklain/Titebond rep re:Calmping Pressure
>
>I am writing in response to your question about clamp pressure.
>First, your calculation and understanding is correct. If you wanted
>to produce 200 psi over an area 12" x 12", you would need 28,800
>pounds of force. On the other hand, it is not clear whether you
>often, or ever, fell short of the actual, required clamp pressure.
>
>The actual required clamp pressure for any bond involving a wood glue
>is a combination of the small amount of pressure required to squeeze
>the glue into a thin, consistent layer, and the pressure necessary the
>compensate for any distortion or lack of fit in the wood stock being
>used. That means when the surfaces of the pieces being joined are
>true, and there is no gap between the pieces when they are dry fit,
>very little pressure is required. If, however, the same assembly is
>being made using pieces which are bowed, twisted or ill-fitted, the
>required pressure is much greater, and is largely the pressure
>required to straighten the wood and pull it into position. Thus, the
>actual required pressure for a bond also reflects the thickness, or
>fight, of the wood involved, with much more pressure obviously
>required to straighten a very thick piece of maple or oak than to
>straighten a thinner piece of the same species.
>
>In many applications, then, pressure, serves to compensate for some
>lack of diligence in wood preparation. That being the case, good wood
>preparation lessens the need for, or dependence on, pressure. In the
>case of our literature, the high suggested pressures reflect the fact
>that those individuals being addressed include those who, at least on
>occasion, are trying to bond thick, poorly fitted pieces of wood, and
>for those readers, the high, suggested values are, indeed, necessary.
>
>Finally, because the bond strength produced in a joint is the result
>of the entanglement of the glue particles which have been drawn into
>the pores and anchored to the wood on the two sides of the joint,
>there is rarely any concern for applying so much pressure that the
>glue is all squeezed out.
>
>In fact, the bond strength achieved increases as the bondline or layer
>of glue becomes thinner. Given that fact, there are only two
>situations in which high pressures may be counterproductive. First,
>there is always a concern that the pores of wood at the bonding
>surfaces not be crushed, and that is the reason that our listed
>pressures are lower for the softer woods. The second situation deals
>with bonds involving end grain or other open grain. There the concern
>is that the open grain is prone to suck up a large amount of glue and,
>if that thirst has not been quenched before clamping, that excessive
>absorption of glue may result in a starved, and weak joint. Because
>most bonds involve face or edge grain which is relatively straight,
>that particular risk is rarely a concern.
What a pleasant way to say "Our glue will hold with little or no
clamping pressure if you guys would get your shit together and make
tight joints with straight wood... lol
Thanks for posting that... it is good info and a reminder to not blame
the glue for my poor workmanship and to be more diligent in learning
good joinery..
http://www.franklinadhesives.com/IntroPageFA.ASP?UserType=1&ProdSel=WNPressPointCalcFA.asptry
this site they own tite bond adhiesives
"Carlos Moreno" <[email protected]> wrote in message
news:[email protected]...
>
> Hi,
>
> I'm wondering if someone knows the actual numbers on glue
> strength? (i.e., strength per unit of surface)
>
> I'm talking about the plastic glue (yellow or white -- I
> think it's vynil-based), assuming that it is used to glue
> two pieces of very-flat very-clean along-the-grain wood
> surfaces, with no gap between the surfaces of more than
> 1/200" or so. At least typical values, or worst-case
> values (if it depends on the wood, or on the angle of
> the surface with respect to the grain, etc.)
>
> A google search on this newsgroup returns nothing; the
> specs of the glue (both on its label and on Lepage's web
> site) only include the catchy advertising phrase "bonds
> with 2 tons of strength" (GOD, such idiots!! Only for
> that I shouldn't buy anything from them!!! :-( such
> flashbacks of infomertials advertising crap), so I'm at
> a loss.
>
> Anyway, I'll be grateful for any info!
>
> Thanks,
>
> Carlos
> --
On Sun, 7 Nov 2004 16:41:21 -0500, "David Chamberlain"
<[email protected]> wrote:
> I was interested so I went down to the shop and took a 12" long X 10" wide
>piece of 13/16" soft maple. I ripped it in half and jointed the dges. I
>used Lee Valley glue and rubbed the two edges together to make sure that I
>had a joint that was evenly coated. I took 3 pipe clamps and used a pipe
>wrench on the handles. The clamps left very nice depressions in the outside
>of the boards.
>
> I let the glue cure overnight and put the piece in my vise. I used a
>ribber mallet and beat the board until it finally broke. It did not break
>along the glue joint. One sample does not prove the issue but I was not able
>to produce a starved glue joint even with 1 clamp every 5 inches or so (1
>clamp 1" in from each and and one clamp in the middle).
>
> A more scientific experiment would involve using a hydraulic press on
>small (1" X 1") samples.
Attached is the text of message from Franklin - makers of titebond.
This msg was originally posted to this forum and am sorry i can't
credit the original poster.
Response from Frnklain/Titebond rep re:Calmping Pressure
After our discussion here, I wrote to technical support at Titebond
regarding our discussion of clamp pressure. I got a next day reply
from a very knowledgeable and helpful gentleman, Mr. Zimmerman. I'm
posting it here.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I am writing in response to your question about clamp pressure.
First, your calculation and understanding is correct. If you wanted
to produce 200 psi over an area 12" x 12", you would need 28,800
pounds of force. On the other hand, it is not clear whether you
often, or ever, fell short of the actual, required clamp pressure.
The actual required clamp pressure for any bond involving a wood glue
is a combination of the small amount of pressure required to squeeze
the glue into a thin, consistent layer, and the pressure necessary the
compensate for any distortion or lack of fit in the wood stock being
used. That means when the surfaces of the pieces being joined are
true, and there is no gap between the pieces when they are dry fit,
very little pressure is required. If, however, the same assembly is
being made using pieces which are bowed, twisted or ill-fitted, the
required pressure is much greater, and is largely the pressure
required to straighten the wood and pull it into position. Thus, the
actual required pressure for a bond also reflects the thickness, or
fight, of the wood involved, with much more pressure obviously
required to straighten a very thick piece of maple or oak than to
straighten a thinner piece of the same species.
In many applications, then, pressure, serves to compensate for some
lack of diligence in wood preparation. That being the case, good wood
preparation lessens the need for, or dependence on, pressure. In the
case of our literature, the high suggested pressures reflect the fact
that those individuals being addressed include those who, at least on
occasion, are trying to bond thick, poorly fitted pieces of wood, and
for those readers, the high, suggested values are, indeed, necessary.
Finally, because the bond strength produced in a joint is the result
of the entanglement of the glue particles which have been drawn into
the pores and anchored to the wood on the two sides of the joint,
there is rarely any concern for applying so much pressure that the
glue is all squeezed out.
In fact, the bond strength achieved increases as the bondline or layer
of glue becomes thinner. Given that fact, there are only two
situations in which high pressures may be counterproductive. First,
there is always a concern that the pores of wood at the bonding
surfaces not be crushed, and that is the reason that our listed
pressures are lower for the softer woods. The second situation deals
with bonds involving end grain or other open grain. There the concern
is that the open grain is prone to suck up a large amount of glue and,
if that thirst has not been quenched before clamping, that excessive
absorption of glue may result in a starved, and weak joint. Because
most bonds involve face or edge grain which is relatively straight,
that particular risk is rarely a concern.
I hope this response is helpful, and ask that you feel free to write
again or to call me at 1-800-###-#### if I can be of any further
assistance.
On Wed, 03 Nov 2004 23:45:51 -0500, Carlos Moreno
<[email protected]> calmly ranted:
>
>Hi,
>
>I'm wondering if someone knows the actual numbers on glue
>strength? (i.e., strength per unit of surface)
What more do you need to know (about strength) than the fact
that the glue is stronger than the wood it bonds?
Don't heat the joint to 150F+ (or soak it in vinegar) and the
bond will last your lifetime or longer.
--------------------------------------------------------
Murphy was an Optimist
----------------------------
http://diversify.com Comprehensive Website Development
On Wed, 03 Nov 2004 23:45:51 -0500, Carlos Moreno
<[email protected]> wrote:
>I'm wondering if someone knows the actual numbers on glue
>strength? (i.e., strength per unit of surface)
Why do you need to know? Have you had glue failure? What are your
spec requirements that the manufacturer should meet? Most modern
brand-name glues do far more than necessary to hold two pieces of wood
together, so the actual rating is unimportant unless you are using it
to build a 747, in which case you'd better make sure as well that the
cuts are flat-accurate to =/-.001" or better. For any glues I know
the wood would shatter well before the bond broke. Any break I've
seen has had wood stuck to it, showing that the break was in the wood,
and not between glue and wood [actual surface-surface bonding]. I'd
be more concerned with other problems such as how long does it take to
set. I had one that grew a mould [mold, US] and had to dump most of
it.
http://www.franklinadhesives.com/IntroPageFA.ASP?UserType=1&ProdSel=WNPressPointCalcFA.asp.
try this site they own Tite bond adhiesive.
"Carlos Moreno" <[email protected]> wrote in message
news:[email protected]...
>
> Hi,
>
> I'm wondering if someone knows the actual numbers on glue
> strength? (i.e., strength per unit of surface)
>
> I'm talking about the plastic glue (yellow or white -- I
> think it's vynil-based), assuming that it is used to glue
> two pieces of very-flat very-clean along-the-grain wood
> surfaces, with no gap between the surfaces of more than
> 1/200" or so. At least typical values, or worst-case
> values (if it depends on the wood, or on the angle of
> the surface with respect to the grain, etc.)
>
> A google search on this newsgroup returns nothing; the
> specs of the glue (both on its label and on Lepage's web
> site) only include the catchy advertising phrase "bonds
> with 2 tons of strength" (GOD, such idiots!! Only for
> that I shouldn't buy anything from them!!! :-( such
> flashbacks of infomertials advertising crap), so I'm at
> a loss.
>
> Anyway, I'll be grateful for any info!
>
> Thanks,
>
> Carlos
> --
Not so sure I agree with the "starved joint" syndrome, merely from the
application of "too much" clamping pressure. Damaged wood fibers can
result from behemoth pressures, but more likely a "starved" joint is due
to insufficient glue applied BEFORE clamping the joint, as opposed to
the pressure of the clamping being the culprit.
David
Sbtypesetter wrote:
> * Clamping pressures are much lower
> than most every woodworker uses. Too
> much pressure will result in a starved
> joint.