An apparatus for clamping a work piece is provided. The apparatus includes a base plate to support the work piece; at least one clamp body fixed to the base plate; at least one fastener fixing the at least one clamp body to the base plate; and a protruding piece having at least a portion thereof inserted into the clamp body and an end thereof extending from a lateral face of the clamp body, the protruding piece including a hollow point tip at the opposite end, where outer and inner lateral surfaces of the hollow point tip join to define a circular sharp edge at the opposite end of the protruding piece.