What you'll need
Tilt the wood in the vice and ensure that the line you’re cutting to is vertical in the vice.
Check with a small square to see that the lines are vertical.
Using the dovetail saw, carefully cut down the vertical lines and stop on the shoulder line. To cut the tails accurately, the sawcuts should be on the waste side of the line. Repeat for the other set of dovetail lines.
Remove the wood from the vice and reposition so that the shoulder line is vertical. This enables the half-pin waste to be cut accurately. Remove the waste on both sides of the board. Saw just a fraction away from the line to allow for cleaning up later with a sharp chisel.
Place the board in the vice and tighten it so that the shoulder line is vertical. Having cut the tails, now use a piercing saw to remove the waste pin material, sawing just above the shoulder line.
Secure the dovetail board to the bench top with a pair of clamps; there should be a thick waste piece underneath and the chisel block should be exactly on the shoulder line.
The chisel block should be dead square with the face side on the dovetail board. The back of the chisel is firmly supported by the face edge.
Use a 12mm chisel to clean up the shoulder line on both the waste half-pins. If the pins are narrow, use a 3mm chisel to clean up the shoulder line; wider pins on bigger work will require a larger sized chisel.