Glue is not stronger than wood.

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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)
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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
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snip
Of a few

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.
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worth). Those pine boards break if you look at them funny. I hope you use better wood in woodworking; the example is worthless.
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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.
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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
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Support it at either end, and make hem break it across the grain.
Hell, have some fun and use some nice springy ash....
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George says...

I vote for jatoba or Peruvian walnut.
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Might be a bit harder to fool the kid into thinking those were pine.
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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.
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.

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.
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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
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no argument exept that if you use NO glue it will surely break at the joint! lol :-]>
skeez
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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
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<SNIP>

<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
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Especially since he uses plenty of brads to hold the joint closed "until the glue sets".
Dave
loutent wrote:

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Anyhow, stronger or not, we DO need to glue. It's definitely weaker without.
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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.
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On 1 Jun 2005 22:21:59 -0700, "Phillip Hallam-Baker"

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
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Chuck says...

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.
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