I need to make another rocking chair and there will be 40 plus m&t joints.
Most will be 1/4" wide, 3/4" to 1 1/4" long and 1 1/8" deep. I've made three
chairs before, so the mortise chopping doesn't spook me, but I've been
unhappy with the consistent quality I've haven't been able to achieve.
I had tried Mr. Gorman's technique of drilling a starter hole in the marked
mortice, but using a twist drill, I didn't have much success.
Fast forward to the Spring 2007 issue of Woodworking Magazine and there is
an article using the Maynard technique. Mr. Schwarz credited Mr. Gorman in
his article. I tried it again, this time using one of my Father's (rip)
Irwin auger bits and a new Lie Nielsen 1/4" mortise chisel. I tried to find
a Ray Iles chisel, but could not find that they are available. Mr. Schwartz
is adamant about using Ray Iles chisels, but if they are not available a Lie
Nielsen chisel will do just fine. They come hand finished to 400 grit and
about 5 minutes had the chisel to 8000 grit.
Using the auger bit does a great job. IIRC, they are 1/64" under sized ( a
micrometer confirmed this). Being slightly undersized, the hole doesn't show
after the mortise is chopped. The depth of the hole sets the depth of the
mortise and the bottom of the mortise is level.
I chopped two mortises in a piece of quarter sawn white oak, and it was a
piece of cake. :-)