I have divided the sole into 2.
I then place the work piece quite low down in the vice as shown.
I start the hacksaw cut on the back edge and work down to the 1/16" depth at an angle, when I have reached the 1/16" depth, I start to lower the cut until the hacksaw blade is just short of cutting into the rear side. Then I turn the sole 180 degrees and do the same on the other side.
Now I finish the 2 cuts together with the hacksaw horizontal, working down to the depth I have marked, 1/16". I use this 12" 24 TPI blade which hasn't got too much set on the teeth, as shown.
A small hacksaw and a thin file just to clean out the grooves.
Now for the shoulders.
Lining the shoulder line exactly with the top of the hardened steel jaws, ready to saw.
Resting the hacksaw on the top face of the jaws, horizontal again, I saw the shoulder cut. When this is reached I transfer to a flat file with one safe edge and remove the rest of the metal, again resting on the hardened jaws working sideways. To finish off I now lift the file onto it's safe edge, resting on the jaws, the file is now vertical and I finish off to the line of the tongue.
This shows the file for the first cut.
This shows the file on it's edge to finish off.
This picture shows one side finished.
I then turn it 180 degrees and do the other side the same.
This picture shows all 4 shoulders cut.
This is a picture of the tongue and grove joint on the sole, pushed together to make a fine mouth. It is held in place when the body is peened to the sole.