Radial arm saw mortise attachment...

woodworker.com: "Woodworker's Supply radial arm saw mortising attachment costs about $200 to set up:

In addition to making precise 90 degree cuts, angled mortises are as easy as using your saw's controls - just as you would to make a miter cut. Designed primarily for timber framers, this versatile tool can be used in furniture making as well. Guard retracts when it contacts workpiece; adjustable depth gauge for consistent and accurate cuts.


** 6-7/8' maximum cut depth.
** 1/4' thick x 2-3/8' wide bar with chain.
** 2,150 FPM chain speed.
** 9' square maximum timber size.
** 1-3/16' radius in bottom cut.
** 1/2' minimum cut distance from table surface; 4-1/2' maximum.
Fits DEWALT, Craftsman and later model DELTA 10' and 12' radial arm saws only."