A work stop (56) for use on a machine vise (10) is received in a jaw plate (20,22) for such vise (10) and is securely locked in position. The work stop (56) is fixed in a groove (58) that is machined int a top edge of the jaw plate (20,22) or jaw, with a member (57) extending over the edge of the jaw plate (20,22) and adjacent the face of the jaw plate (20,22) that is used for clamping a workpiece. This permits the workpiece to be slid against the stop (56) before being clamped. The jaw plate (20,22) is removable mounted onto a fixed jaw (18) and is located precisely relative to the fixed jaw (18) so that the jaw plate (20,22) with the work stop (56) attached an be removed, and then replaced when the same part is to be machined again.