Been a while, good to be back…as to hammer handpiece and bezels, I believe we’re talking about inertia and acceleration…each hammer blow gains acceleration from a standing start and reaches a maximum force at maximum acceleration,which occurs just before the anvil reverses direction and returns to start…hence the need to hold the hammer off the work surface a little. Easy to determine about how far with a little trial and error.
Then, as Rob Meixner notes, a firm hold means the piece that is hit has a greater overall mass (mass of piece plus holding device, assuming a rather rigid hold through a set of jaws or mostly rigid glue of some kind). Wanting something quick, I wonder if a typical bezel setting could be held against the side of a rigid bench pin, anvil or some such. Then it could easily be turned by one hand while the handpiece was directed 180 degrees from where the bezel made contact with the bench pin/bracing surface. I also have a cheap “universal work holder” with moveable pins and jaws which I can hold in a vise, so various workpiece dimensions can be accommodated. I’ll have to give this a try…HTH someone else…royjohn