Michael,

Keep in mind you want to raise the workholding vise close to the diamond engraving spindle, so you don't have to extend the length of the spindle too much, in order to reach your substrate.

That can have a bearing on letter quality. It's much like the difference bewteen trying to write with a pencil, with your fingers close to the lead, as opposed to trying to write with your fingers close to the eraser.

David "The Stunt Engraver" Lavaneri
DGL Engraving
Port Hueneme, CA