Everyone likes to talk about how a good glue joint is stronger than the
wood itself. I think this may be true in a very technical sense, but
absolutely false in practice.
Take for example, a panel glue up with two 5" wide oak boards glued
edge to edge (no biscuits, etc). There is no way in the world that this
panel is stronger than a single 10" wide piece of oak.
If you whack the glued-up panel with a sledgehammer hard enough, it
will split along the glue line. It may take a little wood from either
side of the joint, but is will definitely break right along the joint.
Conversely, the solid 10" wide piece of oak will certainly withstand a
harder blow without breaking than would the glue-up panel.
What am I missing in this 'glue is stronger than the wood itself'
argument?
> If you whack the glued-up panel with a sledgehammer hard enough, it
> will split along the glue line. It may take a little wood from either
> side of the joint, but is will definitely break right along the joint.
>
The glue joint is an irregularity, and if you wack it hard enough to break
the panel, it will probably break at the irregularity.
However, it will not break any easier than the solid panel.
The point of "the glue is stronger than the wood" pretty much means that
there is no advantage to using glue that is twice as strong, because the
glue is already as strong as possible.
Try your little experiment with epoxy; the result will be the same.
<SNIP>
> What am I missing in this 'glue is stronger than the wood itself'
> argument?
>
<SNIP>
Hi Chuck,
Interesting discussion you started....
But...if you actually have glued some wood along the
same grain, you wiould soon realize how strong that
glue joint is
How strong? Strong enough for furniture etc - that's
about all we need.
Besides, Norm sez the glue joint is stronger - good 'nough
for me and my stuff.
Lou
On 1 Jun 2005 11:37:01 -0700, "Chuck" <[email protected]> wrote:
>Everyone likes to talk about how a good glue joint is stronger than the
>wood itself. I think this may be true in a very technical sense, but
>absolutely false in practice.
>
>Take for example, a panel glue up with two 5" wide oak boards glued
>edge to edge (no biscuits, etc). There is no way in the world that this
>panel is stronger than a single 10" wide piece of oak.
>
>If you whack the glued-up panel with a sledgehammer hard enough, it
>will split along the glue line. It may take a little wood from either
>side of the joint, but is will definitely break right along the joint.
>
>Conversely, the solid 10" wide piece of oak will certainly withstand a
>harder blow without breaking than would the glue-up panel.
>
>What am I missing in this 'glue is stronger than the wood itself'
>argument?
A real world application:
My son took Tai Kwan Do a few years back and had to break 1x10 pine
boards with various parts of his body. Breaking practice soon became
expensive, so I decided to re-cut the wider portions of the boards and
edge glue them together with Elmer's carpenter's glue. I clamped them
firmly over night and let them set for a couple of days. Of a few
dozen practice breaks, only one board broke on the glued joint,
leaving "a little wood on either side". All of the other boards broke
somewhere other than the glued joint.
Bill
Chuck wrote:
> That's what I meant by being technically stronger, but not stronger in
> practice. If the glued-up panel breaks with less force than the solid
> wood panel, then the glued up panel is weaker. Whether it breaks clean
> on the glue line, or takes a little wood with it is irrelevant.
I guess it depends on what you mean by "a little wood".
If it takes 1/8" all the way down on either side of the glue line, I
would say the glue like is stronger than the wood itself.
Chuck wrote:
> That's what I meant by being technically stronger, but not stronger in
> practice. If the glued-up panel breaks with less force than the solid
> wood panel, then the glued up panel is weaker. Whether it breaks clean
> on the glue line, or takes a little wood with it is irrelevant.
I guess it depends on what you mean by "a little wood".
If it takes 1/8" all the way down on either side of the glue line, I
would say the glue line is stronger than the wood itself.
>But...if you actually have glued some wood along the
>same grain, you wiould soon realize how strong that
>glue joint is
OK so the cannonical test for this question would be to take a series
of 8/4 10" boards taken from the same tree, resaw them so that you have
pairs of boards that are as near to being identical as possible, then
rip one board from each pair at varying distances from the edge ranging
from (say) 1" through to 5" (the middle).
Then test breaking resistance under both static and dynamic loads
according to a range of configurations.
I suspect however that the test is still not testing the failure mode
that most of us see which is a board that has split due to the wood
shrinking but being unable to move for some reason. Boards glued in
this fashion using pre 1960s glues will most definitely have a tendency
to fail along the glue line, the glues of that era are nowhere near the
quality of modern glues.
>My son also took TKD (even got his black belt, for whatever that must be
>worth). Those pine boards break if you look at them funny.
>I hope you use better wood in woodworking; the example is worthless.
Give the lad a maple board, toughen him up a bit.
Of course to really give 'em a challenge take a 1" thick piece of
polycarbonate (also known as bullet-proof 'glass') and veneer each face
with pine so they can't tell the difference.
"Chuck" <[email protected]> wrote in message
news:[email protected]...
>
> Take for example, a panel glue up with two 5" wide oak boards glued
> edge to edge (no biscuits, etc). There is no way in the world that this
> panel is stronger than a single 10" wide piece of oak.
>
> If you whack the glued-up panel with a sledgehammer hard enough, it
> will split along the glue line. It may take a little wood from either
> side of the joint, but is will definitely break right along the joint.
Instead of two 5" wide boards, glue up a 3" board and an 7" board. Then
whack it with your sledge. I THINK you will find it still splits down the
middle, not on the glue line.
--
********
Bill Pounds
http://www.billpounds.com
In article <[email protected]>,
blueman <[email protected]> wrote:
>"Leon" <[email protected]> writes:
>> "Chuck" <[email protected]> wrote in message
>> news:[email protected]...
>> > That's what I meant by being technically stronger, but not stronger in
>> > practice. If the glued-up panel breaks with less force than the solid
>> > wood panel, then the glued up panel is weaker. Whether it breaks clean
>> > on the glue line, or takes a little wood with it is irrelevant.
>> >
>>
>> NOW you are changing the whole story. In your title you indicate that glue
>> is not stronger than wood. NO ONE has said that glue makes a panel
>> stronger. Most everyone knows that a glued up panel will not break and
>> leave exposed glue, wood is always exposed. Hence the glue is stronger than
>> the wood.
>
>If glue is stronger than wood and the break is along a wood-wood line,
>then why use biscuits or dowels? If anything they would be most needed
>anywhere but the glue line...
Maybe because they are used to help insure _alignment_ of the joint, not
primarily to strengthen it? do you suppose? just maybe? *snort*
In article <[email protected]>, "Chuck" <[email protected]> wrote:
>Everyone likes to talk about how a good glue joint is stronger than the
>wood itself. I think this may be true in a very technical sense, but
>absolutely false in practice.
>
>Take for example, a panel glue up with two 5" wide oak boards glued
>edge to edge (no biscuits, etc). There is no way in the world that this
>panel is stronger than a single 10" wide piece of oak.
Try it. You may be in for a surprise.
>
>If you whack the glued-up panel with a sledgehammer hard enough, it
>will split along the glue line. It may take a little wood from either
>side of the joint, but is will definitely break right along the joint.
I'm guessing you haven't actually attempted the experiment. :-)
>
>Conversely, the solid 10" wide piece of oak will certainly withstand a
>harder blow without breaking than would the glue-up panel.
>
>What am I missing in this 'glue is stronger than the wood itself'
>argument?
Real-world experience.
--
Regards,
Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?
Chuck wrote:
>
> That's what I meant by being technically stronger, but not stronger in
> practice. If the glued-up panel breaks with less force than the solid
> wood panel, then the glued up panel is weaker. Whether it breaks clean
> on the glue line, or takes a little wood with it is irrelevant.
No. If the joint is well-prepared and a good quality glue is properly
applied and cured (even PVA will work), the joint will rarely be what
actually fails. A wide panel breaks more easily because there's a
larger moment arm...actually, the appearance of "easier" is an illusion
as the stress before the breaking point will be (within the variability
of the wood itself) the same.
Have you actually done an experiment or just spouting?
CW wrote:
>
> The glue joint is stronger. It is also less flexible. Stresses that would
> ordinarily fairly evenly spread over the board will concentrate in this hard
> spot.
>
I think that depends on both the specific wood and the specific
glue...pva's, for instance, aren't very rigid. I don't have figures for
modulus, though, but I suspect they're close, at best.
"Chuck" <[email protected]> wrote in message
news:[email protected]...
> Everyone likes to talk about how a good glue joint is stronger than the
> wood itself. I think this may be true in a very technical sense, but
> absolutely false in practice.
>
> Take for example, a panel glue up with two 5" wide oak boards glued
> edge to edge (no biscuits, etc). There is no way in the world that this
> panel is stronger than a single 10" wide piece of oak.
>
> If you whack the glued-up panel with a sledgehammer hard enough, it
> will split along the glue line. It may take a little wood from either
> side of the joint, but is will definitely break right along the joint.
>
> Conversely, the solid 10" wide piece of oak will certainly withstand a
> harder blow without breaking than would the glue-up panel.
>
> What am I missing in this 'glue is stronger than the wood itself'
> argument?
>
Nothing. Glue is not stronger than the wood. It does, however, seem to bond
cellulose stronger than lignin.
Oh yes, your example depends a lot on the orientation of the growth rings.
"Phillip Hallam-Baker" <[email protected]> wrote in message
news:[email protected]...
> >My son also took TKD (even got his black belt, for whatever that must be
> >worth). Those pine boards break if you look at them funny.
> >I hope you use better wood in woodworking; the example is worthless.
>
> Give the lad a maple board, toughen him up a bit.
>
Support it at either end, and make hem break it across the grain.
Hell, have some fun and use some nice springy ash....
Greetings and Salutations...
On Thu, 02 Jun 2005 05:17:35 -0500, Prometheus
<[email protected]> wrote:
>On Thu, 02 Jun 2005 02:49:15 GMT, "toller" <[email protected]> wrote:
>
>
>>> Now I have just about heard everything. The break is PROBABLY not going
>>> to be at the joint. I may be very close to the joint but not at the
>>> joint. Glue is stronger than wood means that the wood will break and the
>>> glue joint will not.
>>You may have heard everything, but evidently you have tried nothing. Break
>>some glued up panels. 90% will be just off the glueline.
>
>Why are you guys so determined to bust up nicely glued panels? Make a
>little tabletop or something out of them, and be happy you had glue
>instead of baling wire or double-sided tape! :)
>
>
>
You kids with your glue...you are LUCKY to have glue. When I
was a boy, we only had snail slime to hold the wood together....and
that on a good day! And we had to walk 10 miles, through the
snow...barefoot...to get to the shop to scrape the wood flat with
our fingernails...
Now...as for the strength issue...It's a non-issue for me.
If it is a structural issue, then, one needs to use plywood, or
something that will provide a panel of appropriate side and strength
without the need of joints. If it is to get a good-looking raised
panel for a door, that is NOT structural, but, DOES require that
the glue joint be cut VERY ACCURATELY. Some folks advocate a slight
cup to the joint, so the ends get crushed together "to keep gaps
from opening up". I advocate making the glue line as straight
as a laser line on BOTH boards. My goal is to joint them so that
when I lay the pieces down on the saw table, and push them together,
the joint closes up and disappears.
The fact of the matter IS that glue is "stronger" than
wood, and, that a well done glue joint WILL hold enough that
the wood will split next to it. However, far too many glue
joints are poorly done - they are starved for glue, or, cut with
such gaps that the glue is acting as a filler, or, (As with a chair
seat I repaired a while ago) the glue surface has been sealed with
finish BEFORE glueing...keeping the glue from penetrating properly.
A bad glue joint is MUCH weaker than wood...and indeed, will split
first.
Regards
Dave Mundt
"J. Clarke" <[email protected]> wrote in message
news:[email protected]...
> They didn't want us to work it because so many of us blinded ourselves
with
> the chips. Dangerous stuff that flaked flint.
>
The micron-sized particles caused silicosis.
<carver3(remove)[email protected]> wrote in message
news:[email protected]...
snip
Of a few
> dozen practice breaks, only one board broke on the glued joint,
> leaving "a little wood on either side".
Umm if a little wood was left on either side of the glued joint, the joint
did not break. I simply broke near the joint. Unless you saw glue down one
edge, the wood broke.
On Fri, 03 Jun 2005 21:16:14 GMT, "Edwin Pawlowski" <[email protected]>
wrote:
>
>"Dave Mundt" <[email protected]> wrote in message
>> And we had to walk 10 miles, through the
>> snow...barefoot...to get to the shop to scrape the wood flat with
>> our fingernails...
>>
>
>You worked inside a building? We used a clearing in the woods at the top of
>a hill where the snow lasted 10 months of the year.
>
Was it up hill both to and from the clearing?
Barry
<carver3(remove)[email protected]> wrote in message
news:[email protected]...
> On 1 Jun 2005 11:37:01 -0700, "Chuck" <[email protected]> wrote:
>
>>Everyone likes to talk about how a good glue joint is stronger than the
>>wood itself. I think this may be true in a very technical sense, but
>>absolutely false in practice.
>>
>>Take for example, a panel glue up with two 5" wide oak boards glued
>>edge to edge (no biscuits, etc). There is no way in the world that this
>>panel is stronger than a single 10" wide piece of oak.
>>
>>If you whack the glued-up panel with a sledgehammer hard enough, it
>>will split along the glue line. It may take a little wood from either
>>side of the joint, but is will definitely break right along the joint.
>>
>>Conversely, the solid 10" wide piece of oak will certainly withstand a
>>harder blow without breaking than would the glue-up panel.
>>
>>What am I missing in this 'glue is stronger than the wood itself'
>>argument?
>
> A real world application:
>
> My son took Tai Kwan Do a few years back and had to break 1x10 pine
> boards with various parts of his body. Breaking practice soon became
> expensive, so I decided to re-cut the wider portions of the boards and
> edge glue them together with Elmer's carpenter's glue. I clamped them
> firmly over night and let them set for a couple of days. Of a few
> dozen practice breaks, only one board broke on the glued joint,
> leaving "a little wood on either side". All of the other boards broke
> somewhere other than the glued joint.
>
My son also took TKD (even got his black belt, for whatever that must be
worth). Those pine boards break if you look at them funny.
I hope you use better wood in woodworking; the example is worthless.
"Chuck" <[email protected]> wrote in message
news:[email protected]...
> Everyone likes to talk about how a good glue joint is stronger than the
> wood itself. I think this may be true in a very technical sense, but
> absolutely false in practice.
>
> Take for example, a panel glue up with two 5" wide oak boards glued
> edge to edge (no biscuits, etc). There is no way in the world that this
> panel is stronger than a single 10" wide piece of oak.
>
> If you whack the glued-up panel with a sledgehammer hard enough, it
> will split along the glue line. It may take a little wood from either
> side of the joint, but is will definitely break right along the joint.
>
> Conversely, the solid 10" wide piece of oak will certainly withstand a
> harder blow without breaking than would the glue-up panel.
>
> What am I missing in this 'glue is stronger than the wood itself'
> argument?
>
I guess I live in a more practical world. If I am designing a project that
is going to be subjected to this kind of stress, use plywood! The strength
difference between a solid and a glued up board would be so close, either
could fail. Why take the chance? Who designes a project that close to
failure points?
Dennis
On Wed, 01 Jun 2005 22:22:03 GMT, skeezics <[email protected]> wrote:
>On 1 Jun 2005 11:37:01 -0700, "Chuck" <[email protected]> wrote:
>>What am I missing in this 'glue is stronger than the wood itself'
>>argument?
>
>no argument exept that if you use NO glue it will surely break at the
>joint! lol :-]>
Not if you use enough biscuits!
--
"We need to make a sacrifice to the gods, find me a young virgin... oh, and bring something to kill"
Tim Douglass
http://www.DouglassClan.com
"Chuck" <[email protected]> wrote in message
news:[email protected]...
.
>
> If you whack the glued-up panel with a sledgehammer hard enough, it
> will split along the glue line. It may take a little wood from either
> side of the joint, but is will definitely break right along the joint.
>
> Conversely, the solid 10" wide piece of oak will certainly withstand a
> harder blow without breaking than would the glue-up panel.
>
> What am I missing in this 'glue is stronger than the wood itself'
> argument?
Reread what you declared in your findings, "It may take a little wood from
either side of the joint," think about it a bit and you will realize that
the glue is stronger than the wood.
"Chuck" <[email protected]> wrote in message
news:[email protected]...
> Everyone likes to talk about how a good glue joint is stronger than the
> wood itself. I think this may be true in a very technical sense, but
> absolutely false in practice.
>
> Take for example, a panel glue up with two 5" wide oak boards glued
> edge to edge (no biscuits, etc). There is no way in the world that this
> panel is stronger than a single 10" wide piece of oak.
>
> If you whack the glued-up panel with a sledgehammer hard enough, it
> will split along the glue line. It may take a little wood from either
> side of the joint, but is will definitely break right along the joint.
>
> Conversely, the solid 10" wide piece of oak will certainly withstand a
> harder blow without breaking than would the glue-up panel.
>
> What am I missing in this 'glue is stronger than the wood itself'
> argument?
>
http://www.newwoodworker.com/useglue.html for a non-chemical discussion of
glue joints. Fact of the matter is that even in your example, while not
absolute, a properly done glue joint is likely to be stronger than the wood
itself. Even oak. (Although I'd suspect that a hardwood like oak would
certainly test the limits of the theory.)
Does seem strange, doesn't it?
James...
In article <[email protected]>, "toller" <[email protected]> wrote:
>You may have heard everything, but evidently you have tried nothing. Break
>some glued up panels. 90% will be just off the glueline.
I don't imagine you've tried it either.... Glue up a test panel eight inches
wide, out of *three* pieces, two 2" wide and one 4" wide, with the 4" piece in
the center. Support it at the edges, and step on it. Where does it break?
--
Regards,
Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?
"Leon" <[email protected]> wrote in message
news:[email protected]...
>
> "toller" <[email protected]> wrote in message
> news:%[email protected]...
>>
>>> If you whack the glued-up panel with a sledgehammer hard enough, it
>>> will split along the glue line. It may take a little wood from either
>>> side of the joint, but is will definitely break right along the joint.
>>>
>> The glue joint is an irregularity, and if you wack it hard enough to
>> break the panel, it will probably break at the irregularity.
>> However, it will not break any easier than the solid panel.
>>
>> The point of "the glue is stronger than the wood" pretty much means that
>> there is no advantage to using glue that is twice as strong, because the
>> glue is already as strong as possible.
>
> Now I have just about heard everything. The break is PROBABLY not going
> to be at the joint. I may be very close to the joint but not at the
> joint. Glue is stronger than wood means that the wood will break and the
> glue joint will not.
You may have heard everything, but evidently you have tried nothing. Break
some glued up panels. 90% will be just off the glueline.
Chuck says...
> What am I missing in this 'glue is stronger than the wood itself'
> argument?
You're missing the fact that in addition to a glue joint in a glued
panel, there is also a break in the continuity of the grain. In other
words, a 12" wide flatsawn one piece board doesn't have a single line of
grain going the length of the board perpendicular to the face. A
perfectly quarter sawn board would have grain running the length of the
board and perpendicular to the face, and in that case it would break in
the same way as the glued panel. So I guess you could say the glue
joint is stronger than the wood, but it isn't as simple as that, because
wood is stronger in some directions than others. If instead of making
glued panels from butt joints you used a scarf joint, it would be a
different ball game.
Dave Mundt says...
> You kids with your glue...you are LUCKY to have glue. When I
> was a boy, we only had snail slime to hold the wood together....and
> that on a good day! And we had to walk 10 miles, through the
> snow...barefoot...to get to the shop to scrape the wood flat with
> our fingernails...
You had feet?
"Robatoy" <[email protected]> wrote in message
news:[email protected]...
> In article <[email protected]>,
> Ba r r y <[email protected]> wrote:
>
>> On Fri, 03 Jun 2005 21:16:14 GMT, "Edwin Pawlowski" <[email protected]>
>> wrote:
>>
>> >
>> >"Dave Mundt" <[email protected]> wrote in message
>> >> And we had to walk 10 miles, through the
>> >> snow...barefoot...to get to the shop to scrape the wood flat with
>> >> our fingernails...
>> >>
>> >
>> >You worked inside a building? We used a clearing in the woods at the
>> >top of
>> >a hill where the snow lasted 10 months of the year.
>> >
>>
>> Was it up hill both to and from the clearing?
>>
>> Barry
>
> Never mind that shit. How many rivers did you have to swim?
Those bone tools were a bitch to maintain an edge on, too.
The glue joint is stronger. It is also less flexible. Stresses that would
ordinarily fairly evenly spread over the board will concentrate in this hard
spot.
"Chuck" <[email protected]> wrote in message
news:[email protected]...
> That's what I meant by being technically stronger, but not stronger in
> practice. If the glued-up panel breaks with less force than the solid
> wood panel, then the glued up panel is weaker. Whether it breaks clean
> on the glue line, or takes a little wood with it is irrelevant.
>
RE: Subject
Bull Shit.
You bring any pair of boards except white oak, and yes that includes
oily teak, any time and I will glue them with some epoxy filled with
some micro-balloons.
You will leave your gonads on the deck trying to break that joint.
For white oak, same as above except resorcinol glue.
Lew
"Chuck" <[email protected]> wrote in message
news:[email protected]...
> That's what I meant by being technically stronger, but not stronger in
> practice. If the glued-up panel breaks with less force than the solid
> wood panel, then the glued up panel is weaker. Whether it breaks clean
> on the glue line, or takes a little wood with it is irrelevant.
>
NOW you are changing the whole story. In your title you indicate that glue
is not stronger than wood. NO ONE has said that glue makes a panel
stronger. Most everyone knows that a glued up panel will not break and
leave exposed glue, wood is always exposed. Hence the glue is stronger than
the wood.
On Thu, 02 Jun 2005 02:49:15 GMT, "toller" <[email protected]> wrote:
>> Now I have just about heard everything. The break is PROBABLY not going
>> to be at the joint. I may be very close to the joint but not at the
>> joint. Glue is stronger than wood means that the wood will break and the
>> glue joint will not.
>You may have heard everything, but evidently you have tried nothing. Break
>some glued up panels. 90% will be just off the glueline.
Why are you guys so determined to bust up nicely glued panels? Make a
little tabletop or something out of them, and be happy you had glue
instead of baling wire or double-sided tape! :)
"Chuck" <[email protected]> wrote in message
news:[email protected]...
> Everyone likes to talk about how a good glue joint is stronger than the
> wood itself. I think this may be true in a very technical sense, but
> absolutely false in practice.
>
> Take for example, a panel glue up with two 5" wide oak boards glued
> edge to edge (no biscuits, etc). There is no way in the world that this
> panel is stronger than a single 10" wide piece of oak.
>
> If you whack the glued-up panel with a sledgehammer hard enough, it
> will split along the glue line. It may take a little wood from either
> side of the joint, but is will definitely break right along the joint.
>
> Conversely, the solid 10" wide piece of oak will certainly withstand a
> harder blow without breaking than would the glue-up panel.
>
> What am I missing in this 'glue is stronger than the wood itself'
> argument?
>
I guess I live in a more practical world. If I am designing a project that
is going to be subjected to this kind of stress, use plywood! The strength
difference between a solid and a glued up board would be so close, either
could fail. Why take the chance? Who designes a project that close to
failure points?
Dennis
Dennis
[email protected] wrote:
> How about if you glued two 2.5" oak boards to either side of a 5" oak
> board and wacked it with a sledgehammer? Would it still break along
> one or both of the glue lines or right in the middle of the glued up
> 10" board?
Bingo--it breaks in the middle because that's the point of maximum stress.
If the OP put the glue line in the middle on his test specimens then he did
not consider all the possible variables.
> Dave
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)
Bob Scratchy wrote:
>
> "Robatoy" <[email protected]> wrote in message
> news:[email protected]...
>> In article <[email protected]>,
>> Ba r r y <[email protected]> wrote:
>>
>>> On Fri, 03 Jun 2005 21:16:14 GMT, "Edwin Pawlowski" <[email protected]>
>>> wrote:
>>>
>>> >
>>> >"Dave Mundt" <[email protected]> wrote in message
>>> >> And we had to walk 10 miles, through the
>>> >> snow...barefoot...to get to the shop to scrape the wood flat with
>>> >> our fingernails...
>>> >>
>>> >
>>> >You worked inside a building? We used a clearing in the woods at the
>>> >top of
>>> >a hill where the snow lasted 10 months of the year.
>>> >
>>>
>>> Was it up hill both to and from the clearing?
>>>
>>> Barry
>>
>> Never mind that shit. How many rivers did you have to swim?
>
> Those bone tools were a bitch to maintain an edge on, too.
Yeah. I remember when that guy came up with flaked flint. Man, what an
improvement that was.
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)
J. Clarke wrote:
> Bob Scratchy wrote:
>
>
>>"Robatoy" <[email protected]> wrote in message
>>news:[email protected]...
>>
>>>In article <[email protected]>,
>>>Ba r r y <[email protected]> wrote:
>>>
>>>
>>>>On Fri, 03 Jun 2005 21:16:14 GMT, "Edwin Pawlowski" <[email protected]>
>>>>wrote:
>>>>
>>>>
>>>>>"Dave Mundt" <[email protected]> wrote in message
>>>>>
>>>>>> And we had to walk 10 miles, through the
>>>>>>snow...barefoot...to get to the shop to scrape the wood flat with
>>>>>>our fingernails...
>>>>>>
>>>>>
>>>>>You worked inside a building? We used a clearing in the woods at the
>>>>>top of
>>>>>a hill where the snow lasted 10 months of the year.
>>>>>
>>>>
>>>>Was it up hill both to and from the clearing?
>>>>
>>>>Barry
>>>
>>>Never mind that shit. How many rivers did you have to swim?
>>
>>Those bone tools were a bitch to maintain an edge on, too.
>
>
> Yeah. I remember when that guy came up with flaked flint. Man, what an
> improvement that was.
Then they found out flaked flint caused cancer. So it was back to the
bone tools for us...
Brian Siano wrote:
> J. Clarke wrote:
>> Bob Scratchy wrote:
>>
>>
>>>"Robatoy" <[email protected]> wrote in message
>>>news:[email protected]...
>>>
>>>>In article <[email protected]>,
>>>>Ba r r y <[email protected]> wrote:
>>>>
>>>>
>>>>>On Fri, 03 Jun 2005 21:16:14 GMT, "Edwin Pawlowski" <[email protected]>
>>>>>wrote:
>>>>>
>>>>>
>>>>>>"Dave Mundt" <[email protected]> wrote in message
>>>>>>
>>>>>>> And we had to walk 10 miles, through the
>>>>>>>snow...barefoot...to get to the shop to scrape the wood flat with
>>>>>>>our fingernails...
>>>>>>>
>>>>>>
>>>>>>You worked inside a building? We used a clearing in the woods at the
>>>>>>top of
>>>>>>a hill where the snow lasted 10 months of the year.
>>>>>>
>>>>>
>>>>>Was it up hill both to and from the clearing?
>>>>>
>>>>>Barry
>>>>
>>>>Never mind that shit. How many rivers did you have to swim?
>>>
>>>Those bone tools were a bitch to maintain an edge on, too.
>>
>>
>> Yeah. I remember when that guy came up with flaked flint. Man, what an
>> improvement that was.
>
> Then they found out flaked flint caused cancer. So it was back to the
> bone tools for us...
They didn't want us to work it because so many of us blinded ourselves with
the chips. Dangerous stuff that flaked flint.
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)
In article <[email protected]>,
Ba r r y <[email protected]> wrote:
> On Fri, 03 Jun 2005 21:16:14 GMT, "Edwin Pawlowski" <[email protected]>
> wrote:
>
> >
> >"Dave Mundt" <[email protected]> wrote in message
> >> And we had to walk 10 miles, through the
> >> snow...barefoot...to get to the shop to scrape the wood flat with
> >> our fingernails...
> >>
> >
> >You worked inside a building? We used a clearing in the woods at the top of
> >a hill where the snow lasted 10 months of the year.
> >
>
> Was it up hill both to and from the clearing?
>
> Barry
Never mind that shit. How many rivers did you have to swim?
In article <[email protected]>,
"Chuck" <[email protected]> wrote:
[snip]
> What am I missing in this 'glue is stronger than the wood itself'
> argument?
Guess Who (IF that's his real name) is right.
If the glue was 'less' strong than the wood, at the break, there would
be glue on either side of the break.
As that never happens (Unless it was a piss-poor job of clamping and
setting of the joint.) there usually is failed wood on either side of
the break, but never failed glue.
So the glue wins every time, end of story.
"IF" total structural integrity of the glued joint is compromised in a
solid piece of the same material (everything else being equal
theoretically) it wouldn't be the fault of the adhesive, but because the
original board has been "cut" discontinuing the structure, NOT because
it was glued.
IOW.. the failure was set to take place at the moment of cutting, not at
the moment of breaking after the adhesion process.
Imagine, if you will, a glue line of 1/8" thick, fully cured Glue
(insofar that is possible to obtain in shit like PVA, but we're being
hypothetical here), attached on both sides to wood, then break that
lamination, and I assure you, the wood would give up parts to the
adhesive, and the adhesive would stay in one piece.
Test this theory on end grain particle board (Legal in this argument as
it negates any unpredictability). You will find the break to be either
on the left side of the joint or the right, but never in the exact
middle, most of the time a jagged break with material on either side.
As a countertop guy, this kinds stuff is important to me and I have
tested that with every glue I have ever bought, I hate to get stuck with
a 5 gallon pail of stuff that doesn't work.
To help a lot in making the joint stronger, one would be smart to
lengthen the glue line by using TruMatch or finger joints, in the hope
to restore some of the continuation of the 'cut' fibrous or granular
structure of the wood in question.
Rob
The moon is smaller than the earth even though it is further away.
On 1 Jun 2005 11:37:01 -0700, "Chuck" <[email protected]> wrote:
>Everyone likes to talk about how a good glue joint is stronger than the
>wood itself. I think this may be true in a very technical sense, but
>absolutely false in practice.
>
>Take for example, a panel glue up with two 5" wide oak boards glued
>edge to edge (no biscuits, etc). There is no way in the world that this
>panel is stronger than a single 10" wide piece of oak.
Have you tried it??
>
>If you whack the glued-up panel with a sledgehammer hard enough, it
>will split along the glue line. It may take a little wood from either
>side of the joint, but is will definitely break right along the joint.
I've tried this at least three times. Everytime the glue line was
left intact. However, a end-to-end grain is very weak.
>
>Conversely, the solid 10" wide piece of oak will certainly withstand a
>harder blow without breaking than would the glue-up panel.
>
>What am I missing in this 'glue is stronger than the wood itself'
>argument?
Take some scraps and try it yourself. Allow the glue to cure for 2
days before swinging the sledge hammer. You'll become a believer.
Chuck wrote:
> That's what I meant by being technically stronger, but not stronger in
> practice. If the glued-up panel breaks with less force than the solid
> wood panel, then the glued up panel is weaker.
Does it? Have you tried? I haven't but I pretty much doubt it, never
had a glue joint break.
--
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
"blueman" <[email protected]> wrote in message
news:[email protected]...
> "Leon" <[email protected]> writes:
>> "Chuck" <[email protected]> wrote in message
>> news:[email protected]...
>> > That's what I meant by being technically stronger, but not stronger in
>> > practice. If the glued-up panel breaks with less force than the solid
>> > wood panel, then the glued up panel is weaker. Whether it breaks clean
>> > on the glue line, or takes a little wood with it is irrelevant.
>> >
>>
>> NOW you are changing the whole story. In your title you indicate that
>> glue
>> is not stronger than wood. NO ONE has said that glue makes a panel
>> stronger. Most everyone knows that a glued up panel will not break and
>> leave exposed glue, wood is always exposed. Hence the glue is stronger
>> than
>> the wood.
>
> If glue is stronger than wood and the break is along a wood-wood line,
> then why use biscuits or dowels? If anything they would be most needed
> anywhere but the glue line...
Consider the real-world mechanics of gluing two long strips of wood, long
edge to long end. Even the most minor of variations in thickness, or very
minor twisting will make the glue joint very hard to get perfect flat, even
with clamps. Both dowels and biscuits will allow aligning the flat, wide
surfaces, much better.
On 1 Jun 2005 11:37:01 -0700, "Chuck" <[email protected]> wrote:
>Everyone likes to talk about how a good glue joint is stronger than the
>wood itself. I think this may be true in a very technical sense, but
>absolutely false in practice.
>
>Take for example, a panel glue up with two 5" wide oak boards glued
>edge to edge (no biscuits, etc). There is no way in the world that this
>panel is stronger than a single 10" wide piece of oak.
>
>If you whack the glued-up panel with a sledgehammer hard enough, it
>will split along the glue line. It may take a little wood from either
>side of the joint, but is will definitely break right along the joint.
I think Chuck just propped up a tar baby, but I'll take a poke at it
anyway. If "it takes a little wood from either side" doesn't that
mean that the glue is stronger than at least the part that it was
taken from?
In article <[email protected]>,
Edwin Pawlowski <[email protected]> wrote:
>
>"Dave Mundt" <[email protected]> wrote in message
>> And we had to walk 10 miles, through the
>> snow...barefoot...to get to the shop to scrape the wood flat with
>> our fingernails...
>>
>
>You worked inside a building? We used a clearing in the woods at the top of
>a hill where the snow lasted 10 months of the year.
>
>
You had woods?
--
Larry Wasserman Baltimore, Maryland
[email protected]
On 1 Jun 2005 11:37:01 -0700, "Chuck" <[email protected]> wrote:
>Everyone likes to talk about how a good glue joint is stronger than the
>wood itself. I think this may be true in a very technical sense, but
>absolutely false in practice.
>
>Take for example, a panel glue up with two 5" wide oak boards glued
>edge to edge (no biscuits, etc). There is no way in the world that this
>panel is stronger than a single 10" wide piece of oak.
>
>If you whack the glued-up panel with a sledgehammer hard enough, it
>will split along the glue line. It may take a little wood from either
>side of the joint, but is will definitely break right along the joint.
>
>Conversely, the solid 10" wide piece of oak will certainly withstand a
>harder blow without breaking than would the glue-up panel.
>
>What am I missing in this 'glue is stronger than the wood itself'
>argument?
no argument exept that if you use NO glue it will surely break at the
joint! lol :-]>
skeez
On 1 Jun 2005 12:43:03 -0700, "Chuck" <[email protected]> wrote:
>Whether it breaks clean
>on the glue line, or takes a little wood with it is irrelevant.
No it's not. It's the key, as I already suggested in another post.
If it takes wood with it, then the break is wood-wood. If the
glue-wood bond isn't stronger, it will break away from the wood. That
is the glue and wood will separate, or the glue itself will separate,
with some still adhering to both bits of wood. Try using a *much*
lighter glue for example, or bashing itbefroe the glue has completely
set, but is adhering. The parts will separate easily at the joint.
In fact, this is the reason for failure of some joints.
"David" <[email protected]> wrote in message
> Is that the disease one would get from inhaling too deeply near Pam
> Anderson's chest?
No. In a case like that, you'd probably get punchinthenose itis.
"Chuck" <[email protected]> wrote in message
news:[email protected]...
> That's what I meant by being technically stronger, but not stronger in
> practice. If the glued-up panel breaks with less force than the solid
> wood panel, then the glued up panel is weaker. Whether it breaks clean
> on the glue line, or takes a little wood with it is irrelevant.
>
Well, Chuck, if you were out trolling, you got quite a catch.
If that's a serious statement though, you should realize that you're talking
about two different questions:
1) Is the GLUE JOINT stronger than the wood itself?
2) Is a glued panel stronger than a solid panel of the same size?
I have no doubt that the answer to (1) is Yes. Saw it for the first time in
junior high shop class, and I've seen it several times since, even on
smaller pieces. It always breaks the wood, not in the glue line.
The answer to (2) may very well be No, that is, a glued panel probably is
weaker. But I think that has more to do with stress concentrations than the
glue joint being weak. It's been a while since engineering school, so I
might not do an adequate job of explaining, but I definitely remember the
idea of stress risers. With any material under stress, discontinuities in
the material create higher concentrations of stress around them. Think of
sharp inside corners on rotating shafts, things like that. Why do you think
corners are radiused on a crankshaft? It reduces the stress riser. The
stress at the discontinuity is going to be higher than the nominal stress in
the part.
I'd suggest that's exactly what's happening to a glued panel. The local
stress is probably stronger around the glue line. (And that's what most
people see is that the break happens near the glue line). A panel that is
one solid piece doesn't have the higher localized stresses. (Except maybe
around knots and things of that sort. But knots don't run the length of the
panel).
Anyway, question (2) is pretty much academic, since most of us don't have
access to boards wide enough to make a tabletop from one piece.
"Leon" <[email protected]> writes:
> "Chuck" <[email protected]> wrote in message
> news:[email protected]...
> > That's what I meant by being technically stronger, but not stronger in
> > practice. If the glued-up panel breaks with less force than the solid
> > wood panel, then the glued up panel is weaker. Whether it breaks clean
> > on the glue line, or takes a little wood with it is irrelevant.
> >
>
> NOW you are changing the whole story. In your title you indicate that glue
> is not stronger than wood. NO ONE has said that glue makes a panel
> stronger. Most everyone knows that a glued up panel will not break and
> leave exposed glue, wood is always exposed. Hence the glue is stronger than
> the wood.
If glue is stronger than wood and the break is along a wood-wood line,
then why use biscuits or dowels? If anything they would be most needed
anywhere but the glue line...
"blueman" <[email protected]> wrote in message
news:[email protected]...
> "Leon" <[email protected]> writes:
>> "Chuck" <[email protected]> wrote in message
>> news:[email protected]...
>
> If glue is stronger than wood and the break is along a wood-wood line,
> then why use biscuits or dowels? If anything they would be most needed
> anywhere but the glue line...
Umm because the glue line is STRONGER than the WOOD. Use biscuits for butt
joints or mitered joints where the end grain of the wood is going to pull
out of the end of the board.
"toller" <[email protected]> wrote in message
news:%[email protected]...
>
>> If you whack the glued-up panel with a sledgehammer hard enough, it
>> will split along the glue line. It may take a little wood from either
>> side of the joint, but is will definitely break right along the joint.
>>
> The glue joint is an irregularity, and if you wack it hard enough to break
> the panel, it will probably break at the irregularity.
> However, it will not break any easier than the solid panel.
>
> The point of "the glue is stronger than the wood" pretty much means that
> there is no advantage to using glue that is twice as strong, because the
> glue is already as strong as possible.
Now I have just about heard everything. The break is PROBABLY not going to
be at the joint. I may be very close to the joint but not at the joint.
Glue is stronger than wood means that the wood will break and the glue joint
will not.
On 1 Jun 2005 22:21:59 -0700, "Phillip Hallam-Baker"
<[email protected]> wrote:
>I suspect however that the test is still not testing the failure mode
>that most of us see which is a board that has split due to the wood
>shrinking but being unable to move for some reason. Boards glued in
>this fashion using pre 1960s glues will most definitely have a tendency
>to fail along the glue line, the glues of that era are nowhere near the
>quality of modern glues.
Hide glue, which has been around a *long* time, is still stronger than
the wood if the joint is prepared well and it hasn't been exposed to
either moisture or excessive heat.
--
"We need to make a sacrifice to the gods, find me a young virgin... oh, and bring something to kill"
Tim Douglass
http://www.DouglassClan.com
On 1 Jun 2005 12:43:03 -0700, "Chuck" <[email protected]> wrote:
>That's what I meant by being technically stronger, but not stronger in
>practice. If the glued-up panel breaks with less force than the solid
>wood panel, then the glued up panel is weaker. Whether it breaks clean
>on the glue line, or takes a little wood with it is irrelevant.
Dat Brer Fox he'd sho be de sly one.
On 1 Jun 2005 11:37:01 -0700, "Chuck" <[email protected]> wrote:
>What am I missing in this 'glue is stronger than the wood itself'
>argument?
It's a matter of adhesion: Glue-wood, or wood-wood.
A simple test: Drop some glue directly onto some wood. Let it dry
hard. Try to remove the glue without taking along some wood.
On Wed, 01 Jun 2005 20:58:25 -0400, loutent <[email protected]> wrote:
>Interesting discussion you started....
>
>But...if you actually have glued some wood along the
>same grain, you wiould soon realize how strong that
>glue joint is
Anyhow, stronger or not, we DO need to glue. It's definitely weaker
without.
Chuck wrote:
> Everyone likes to talk about how a good glue joint is stronger than the
> wood itself. I think this may be true in a very technical sense, but
> absolutely false in practice.
>
> Take for example, a panel glue up with two 5" wide oak boards glued
> edge to edge (no biscuits, etc). There is no way in the world that this
> panel is stronger than a single 10" wide piece of oak.
>
> If you whack the glued-up panel with a sledgehammer hard enough, it
> will split along the glue line. It may take a little wood from either
> side of the joint, but is will definitely break right along the joint.
>
> Conversely, the solid 10" wide piece of oak will certainly withstand a
> harder blow without breaking than would the glue-up panel.
>
> What am I missing in this 'glue is stronger than the wood itself'
> argument?
>
It sounds like you tested a glue joint that was not joined properly.
I've never had a properly glued up panel break at the glue line when tested.
--
Jack Novak
Buffalo, NY - USA
[email protected]
(Remove -SPAM- to send email)
"Dave Mundt" <[email protected]> wrote in message
> And we had to walk 10 miles, through the
> snow...barefoot...to get to the shop to scrape the wood flat with
> our fingernails...
>
You worked inside a building? We used a clearing in the woods at the top of
a hill where the snow lasted 10 months of the year.