3. Using a mortise marking gauge, mark thetenon thickness onto the mortise member, between the two marked lines. Do this on both sides.
4. Remove the waste from the mortise with a chisel. Take small cuts and work halfway through on one side, then turn the workpiece over and work through from the other side, to ensure a neat finish.
5. Saw the waste off the tenon with a tenon saw. Cut the shoulders first and then remove the cheeks.