Just Wondering wrote:
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.

Correct.

--

-Mike-