How much of my part should sit in the vise?

Side-to-side (in X): to minimize chatter, as much of your part as possible should be inside the vice (instead of hanging out of the vice).

Vertically (in Z): the part should rest on top of the parallels and be held securely in the vice. We often want as much of our part as possible to be within the vice (below the top of the vice) so that it is more secure. A good rule of thumb is to have at least ⅛” of the part in the vice. If the part tends to lean or slip out of the vice, reconfigure it to be flatter and more stable.