A Hand-Chopped Timber Mortise in 6 Steps
Step 1: Lay out the mortise on your timber using a speed square. In this example we are laying out the mortise for a 4 x 8 curved knee brace with a 2” tenon.
Step 2: After double checking your measurements, score the front and back of your mortise using a 2” framing chisel (a knife will work if you don’t have a 2” chisel). This step is to avoid chip-out in steps 4-5.
Step 3: Set a 7 1/4 in circular saw to full depth and plunge cut the sides of your mortise. This will give the sides of the mortise a clean edge and make material removal easier in steps 4-6.
Step 4: Using a 2 in Wood-boring Forstner bit, drill a series of holes starting at the bottom of the mortise working your way up. We are leaving 1in un-drilled at the top of our mortise to accommodate the angled knee brace.
Step 5: Because we are chopping a mortise for a knee brace on a 45 degree angle, we need to chop the front of our mortise at a 45 degree or steeper angle to receive the brace tenon.
Step 6: Using your framing chisel simply clean up the mortise by removing all waste.
And there you have it, the secrets have been revealed! A hand-chopped timber mortise in 6 steps.