I learned to engrave in England, mostly for stone setting. The
benches we used were the more typical european style with the deep
“C” shaped cutout.
The reason it matters is that you can use the sides of the deep
cutout to brace yourself against. Assuming right handed, your left
shoulder goes against the left side of the cutout, while your right
elbow goes up on the tabletop. The idea being to brace against the
left, and use the right to support your arm. All those big muscles in
the shoulder are intended for throwing rocks at dinner, not fine
engraving, so it’s best to get them out of the equation by way of
resting the right arm on the tabletop. So all the control moves are
coming from the right wrist, and the turns are coming from the left
hand.
I’ve got a ‘how to make a frankenbench’ thing on my website that
shows the style I’m talking about.
The reason it matters is that you can use the sides of the deep
cutout to brace yourself against. Assuming right handed, your left
shoulder goes against the left side of the cutout, while your
right elbow goes up on the tabletop. The idea being to brace
against the left, and use the right to support your arm. All those
big muscles in the shoulder are intended for throwing rocks at
dinner, not fine engraving, so it's best to get them out of the
equation by way of resting the right arm on the tabletop. So all
the control moves are coming from the right wrist, and the turns
are coming from the left hand.
I want to add to that one more reason. To sharpen I use 2 8 inch
stones positioned in line. When transitioning from one to another,
one should be able to move deeper into the bench, so the position of
the elbow would remain the same. This is also establishes requirements
of the bench to be at least 20 inches deep.