A mounting assembly for pivotally mounting a workpiece holder to a support structure includes a mounting member having an opening at least partially therethrough and a swivel member. The swivel member has a generally cylindrical passageway therethrough for at least partially receiving a support structure. The swivel member defines a truncated, generally spherical shaped swivel member having a curved outer surface for engaging an inner surface of the opening of the mounting member. The swivel member includes a reduced diameter or chamfered portion at the outer surface to facilitate insertion of the swivel member into the opening of the mounting member, whereby the swivel member is substantially retained within the opening after insertion therein. The mounting member may be a mounting bracket for adjustably mounting to a workpiece holder or may be a mounting block which is attachable to a workpiece holder.