Special techniques to cutting a non-90 degree mortise?
Just try laying it out on a board the same dimensions as the legs you are proposing.
Draw your 5 to 7 degree lines on a face of the board, and draw a second parallel line spaced the thickness of the mortise. If a through mortise, the thickness of your work piece.
Take a square and draw 90 degree lines to the previous drawn lines as wide apart as you can, yet remain betwen the lines. It will show you how much wood needs to come off the tenon to fit.
If you are cutting by hand these angled tenons should be no harder to do than straight cut tenons.
Last edited by Terry Q; 12-18-2019 at 10:01 AM.