"Just Wondering" wrote in message

On 11/20/2013 5:22 AM, Mike Marlow wrote:
dadiOH wrote:
I used to make lots of them. Now, less because I
have more tools but I still do on occasion and I
wonder why they work? We all know that wood expands
and contracts and lap joints have to pieces of wood
doing that at right angles to each other yet they
remain nice and solid. How come? Someone might say it is because each
piece is narrow
and doesn't move much. That is true but I've often
made fairly wide laps. For example, all our toilet
seats are wood, each made with four pieces about 3"
wide lapped at the corners. Discussion is invited.

I'll throw out the thought that it's because the wood
does not move at the joint. The glue successfully
holds that joint together as a unit. This might be
easier to see with edge glued boards. The boards may
move some with varying conditions, across their width,
just not at the joint where it is glued.
Plywood is just a huge sheet of lap joints. It seems to
hold together OK.

Main difference is that the layers are thin.

--

dadiOH
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