The bit removes most of the material, and the chisel squares up the sides, allowing you to cut precise 3/8” mortises for mortise-and-tenon joints. Fits the Jet Benchtop Mortising Machine (#81421, sold separately).
WARNING: Drilling, sawing, sanding or machining wood products can expose you to wood dust, a substance known to the State of California to cause cancer. Avoid inhaling wood dust or use a dust mask or other safeguards for personal protection. For more information go to www.P65Warnings.ca.gov/wood.
Head of the drill bit was nicked and the tips of the 4 corners were not even. Had a friend sharpen the bit and the chisel and it then worked fine. Bit would fit my 5/8 inch collar on the mortising attachment to my drill press. All the better bits I found required a 3/4 inch collar so I was so of stuck with what I had. OBTW, Rockler's return policy/process is difficult to use.
How long is the exposed shaft of the bit above the shank when fully retracted? I have a chisel I can't use with a Delta mortising attachment because the bit shaft is not long enough to reach the teeth of the chuck when fully retracted into the chisel, and I don't need another one of those.