Glue is not stronger than wood.

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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.
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Try it. You may be in for a surprise.

I'm guessing you haven't actually attempted the experiment. :-)

Real-world experience.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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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.
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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.
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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.
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some glued up panels. 90% will be just off the glueline.
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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! :)
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    Greetings and Salutations...
On Thu, 02 Jun 2005 05:17:35 -0500, Prometheus

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
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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.
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wrote:

Was it up hill both to and from the clearing?
Barry
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Never mind that shit. How many rivers did you have to swim?
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wrote in message

Those bone tools were a bitch to maintain an edge on, too.
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Bob Scratchy wrote:

Yeah. I remember when that guy came up with flaked flint. Man, what an improvement that was.
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--John
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J. Clarke wrote:

Then they found out flaked flint caused cancer. So it was back to the bone tools for us...
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Brian Siano wrote:

They didn't want us to work it because so many of us blinded ourselves with the chips. Dangerous stuff that flaked flint.
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--John
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The micron-sized particles caused silicosis.
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Is that the disease one would get from inhaling too deeply near Pam Anderson's chest?
Dave
George wrote:

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No. In a case like that, you'd probably get punchinthenose itis.
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You had woods?
--

Larry Wasserman Baltimore, Maryland
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Dave Mundt says...

You had feet?
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