Loose Wedge through mortise and tenon

[Stewart Crick]

I'm getting ready to make my first wedged mortise and tenon; in looking through Gary Rogowski's Joinery book I can't help but notice a couple of key facts missing. For example, he talks about ensuring you leave enough wood at the end of the tenon to prevent the short grain from shearing off, but he doesn't discuss how much wood you should leave. 1", 2"? My guess is that it's proportional to the whole tenon/wedge configuration.

Which leads to my next question....

How thick, wide, long should the wedge be?

I'm using the joint to hold the bottom shelve of a stool in place. The mortise is 1.5" x .75" through 3/4" QS white oak.

Stu

[Brian Hale]

Page 372 shows 2"-3". Is that what your looking for?

[Stewart Crick]

hmmm...Not sure. I'm doing a horizontal type like shown on page 140. Are there different stresses, or is one the same as the other just rotated 90 degrees?

[Michael Ballent]

Check out FWW web site... They have a video online that may answer some of your questions... From what I remember, you are supposed to angle part of the mortise so when you drive the wedge into the tennon will open up into the mortise and lock the whole thing together... HTH

[Brian Hale]

I haven't done one like your doing so i can't give an experienced answer, however, if your concerned abot the short grain breaking, and i would be, perhaps you could insert a dowel through the tenon, 90 degrees to the wedge just outside of where the wedge is for some added strength. Some different colored wood might make a nice accent.

Brian