David wrote:
Thanks for those suggestions, but as I previously posted
a flat bottom on the mortise isn't my concern.

David.



True But going all the way through should eliminate all artifacts
leaving just a clean, square hole. Any tear out on the exit side is
covered by the bottom piece.

BTW There is another old way to do this but since you have a mortiser I
suggested the above. You can start with pieces as thich as half the
width that you want and cut grooves with a dado blade. Then glue the
two halves together to make your clean square holes.