Abstract: A clamp assembly adaptable for retaining workpieces of various sizes and shapes includes an elongated metal bracket provided with a plurality of equally spaced perforations in parallel relationship to each other and two movable members for retaining the workpiece, having fingers for cooperating with the perforations to removably and interchangeably secure the retaining members to the bracket in one of a plurality of opposed spaced relationships. A portion of at least one of the retaining members is adjustable for engaging the workpiece and applying a sufficient force against the workpiece to retain it between the two members. The fingers of each retaining member engage perforations of the bracket in a manner such that the retaining members are locked into position in response to the force being applied to the workpiece by the engaging portion of the retaining members. The retaining members may be elevated by employing one or more elevating blocks which are removably secured to the bracket and to each other.