An improved adjustable work stop device for use in positioning work pieces which for machining purposes are clamped in a vice or other clamping means. The work stop comprises a laterally adjustable base, a flipper mount with flip arm movable in a vertical direction and lockable into desire position thereto, a flip arm with a positioner which is pivotably secured and rotates away from the work piece without scrubbing the work piece surface whereby clearance for machining, work or the like is accomplished on the butted side of the work piece.