I got a request from one of my students for further explanation on how to make a mitered finger joint sled. As it was something I'd never made before in my life, and have never known to have been made by anyone else, I've done a sketch of it in hopes that a few can understand. It seems to be an invention of my own. I've also proposed an article for Fine Woodworking to allow me a better opportunity to explain its use. You can gain some insight into its use from P. 62 of my book Complete Illustrated Guide to Box Making where the joint is cut using a miter gauge on the table saw.
sled has a single runner so it can be used serially on the left and
right miter gauge guide slots, with the blade cutting on one side to cut
one corner and the other to cut its mate. The adjustable stop is also
used alternately on one side and then the other, and is held in place
with a "c" clamp. the fences are attached at 45 degree angles with
screws and it is essential that space be left between them to allow for
positioning the adjustable stop.
If you don't
understand this process, that's understandable. A mitered finger joint
is a rather complex box making technique. You will want to start with
simple joints and work your way toward greater complexity over time,
which happens to correspond with one of the simple rules of Educational
Sloyd. Move from the simple to the complex. It is relatively simple to
understand a box joint. It is relatively simple to understand a miter.
You will want to have both mastered before you proceed to more complex
joints involving both joinery techniques in the same corner of a box.
Make, fix and create.