Mortise and Tenon

[Smoothjazz077]

I haven't used the mortise and tenon joint in my woodworking until a project I am currently working on. I am doing the joinery by hand, and just finished chopping out the mortise. Is there a guideline on how deep a mortise should be for the tenon? The project I am working on will have a high load weight requirement. My mortise is 1" in depth, and is 3" in length. Is 1" deep enough?

Thanks
Scott

[Smoothjazz077]

Building tools stands that will be supporting a 80lb bench top tool.

[Admiral]

I generally make the mortise depth around 1/3rd of the width of the piece being mortised, you could go deeper, actually through it; and the thickness of the tenon 1/3rd the thickness of the piece being tenoned. I don't have any source for this except for a crusty old guy named Gus (he's since passed) who told me that 30 years ago. Works for me, have never had a joint fail.

[MichaelMouse]

Probably are a bunch of rules - by any number of fools. In your case, the load will be borne on the endgrain of the legs - almost always the truth - so the tenons are there to prevent rail racking. It's the shoulder that counts most in those constructions, with the tenon long enough to contain a pin to draw bore it and keep the shoulder in firm contact. In hard wood, probably ~3/4" with the draw midway or favoring the entry.

Fox wedged tenon could be shorter.