Removing the Ridge

To remove the center ridge and level the bottom of the recess, use the widest chisel that will fit comfortably between the walls. Make sure it’s newly sharpened.

Secure your work in the vice and, beginning at one end, take out the very corner with the chisel bevel up and shooting upwards. Use the heel of your hand to hit the handle of the chisel, but don’t try to take out a lot at once. This would be very hard on your hand and you wouldn’t finish any quicker. Instead, only take off a little at a time, using medium taps to create a continuous flat all the way up to the top face.

When you’ve come down half of the depth or so, switch to a double handed grip of the chisel and pare across the recess, applying a very controlled force. Keep pointing upwards. Repeat these cuts, going a little deeper every time, until you reach the depth line. Always stop before getting to the opposite end, as the corner could break off and split below the gauge line. Instead, turn around and work in the same way towards the middle from the other side.