On Wed, 14 Jan 2015 18:13:15 -0600
Leon lcb11211@swbelldotnet wrote:

Several years back Bridge City Tools manufactured and sold a Kerf
Maker, a dandy tool for cutting dado's and grooves perfect in width
with undersized blades and router bits. I own one and it worked
extremely well for cutting 3/64" deep half lap joints 1/2" wide with
a 3/8" wide dado set.

This guy builds one and may have had too much coffee before he began
filing and sanding.

https://www.youtube.com/watch?v=YsfOWa_TFR8#t=198

The end product is nice. But those fingers so close to fast moving
sharpened steel uncomfortable to watch. Maybe it's the fast-motion
of the videos but there seemed to be too many times when his fingers
were in a position where if something went wrong it might be bad.