Dining room table mortise and tennon

[Carl Beckett]

I had a M/T joint that I made tight to the top/bottom - where some expansion caused the area above the tenon to pop out that cross section of wood (admittedly this was air dried elm on my workbench, and was not ideally dried).

I always imagined that since the grain pattern went 90 degrees it would be desirable to have a gap above/below just to allow some differential expansion. So leaving the top open would serve the same.

'Most' of these type of constructions I put a 45 reinforcement in the corner. Either dovetail so it will slide in from the top, or pocket screws. My table takes a fair bit of abuse.

[Carl Beckett]

I was grateful that none of you thought I was totally out of my mind.

This is a separate thread...

[John Kananis]

All fair (and true) statements but why move away from what's worked for so many centuries? I haven't had a glue joint fail but if one of my pieces is passed on after I'm gone, there's a chance it will. I suppose I'm just sticking with what I was taught and has worked for me, certainly not saying my way of the only right way. As always, I appreciate the perspective.

I should have better explained. Cope and stick joinery has some form of tenon, too. In cabinet doors it's often a stub tenon. In passage doors it's either a M&T, a loose tenon, or dowels. In any case, it's the glued area that carries the load, to which the cope and stick add significantly. Traditional M&T is great. It's probably the only joint that will work if you leave out the glue and draw bore or otherwise mechanically secure the joint. But once you use glue neither the draw bore nor the shoulders add anything - unless the glue fails. I'm pretty sure FWW test data showed half lap and I think bridle joints, too, with higher strength to failure than M&T ones. Because the glued surface area is higher. When the other joints fail, the parts break apart easily, whereas M&T will still support significant load. BUT, the M&T joints failed earlier. I'll take higher breaking strength. When was the last time you had a glue joint failure?

John

[Cameron Wood]

I recently dismantled a large armoire- Dutch colonial from Ceylon. Probably over 200 years old, mortise and tenon joinery pinned with tapered pins. No glue. Some small bronze nails fastening ebony trim, and a few iron nails- very rusted. The joinery was all in good shape.

[Edward Weber]

Lots of good/different viewpoints in this thread.
Personally, I prefer a joint to be mechanically sound, with glue being only there for the added insurance. Should the glue fail, the joint wont. This is the type of joint I used in the little bench I posted.

[Craig Shipman]

Great article, Thanks Chris. Now I am rethinking it