M & T Question

[Bill Holt]

In 13/16" walnut stock a 3/8" mortise looks too big but a 1/4" tenon looks too weak.  Is a 5/16" tenon strong enough?  What say the WN brain trust?

I'm building a frame & panel Quilt Display Cabinet with glass for the front panel and top panel. The frame stock is 13/16" x 2 1/4" walnut.

[Gary G™]

I've done a bunch of doors with 5/16" M&Ts.
Done enough I added a router bit that size.
Haven't had problems.
The beauty, of course, is the easily measured 1/4" shoulder.

[fredhargis]

I'd say in most cases the 1/4" tenon is strong enough, so I'd certainly say the 5/16" is.

[Bill Holt]

Thank you for the conformation.  Guess I needed a little push.

[rwe2156]

I've read rule of thumb is 1/3 but in 3/4 stock I generally go with 3/8.

I think it depends on application.  For typical furniture a 1/8 - 3/32" shoulder (long side) is adequate with a wider shoulder for short side to prevent racking.

[Bibliophile 13]

I'd just go with a 1/4", myself. 5/16" would be okay, too.

Don't get too worried about it, either way. M&T makes for very strong joinery, even if the proportions don't exactly line up with ideal best-practices.

[Bill Holt]

An update.  I went for the 5/16".  The tenon is 1 1/2" long and 1 11/16" wide.  The top of the cabinet is the lid and the top "panel" will be 3/16" glass and I want to use the Rockler lid-stay torsion hinges.  I have used the hinge before and really like it.   My concern: The two tenons on the back will have to carry the weight of the glass.  Has anyone here done this before?