I am making a bed headboard which requires multiple mortise and tenon joints on different wood thicknesses. I am routing my mortises and seeing the stop line that was laid out for the mortise was challenging at times. I wanted a stop block that would be easy to use and would be versatile enough to use on all the various thicknesses.
I used some scrap maple from the headboard and drilled a hole in the top piece, then cut a slot with a scroll saw. I lined up the stationary vertical piece with the edge of the top piece and countersunk two screws. I then drilled a pilot hole in the movable vertical piece, placed a round head screw with a washer through the slot and screwed it into the pilot hole loosely enough that the piece could move freely.
I also placed adhesive backed sandpaper on the inside of each vertical piece to help hold it in place with a quick clamp. -Bill Giesy