An adjustable support for workpieces is provided with a tripod base in which each of the three legs includes an angle bar having a vertical top segment. The top segments of the legs are securely connected together by a polyhedron shaped junction member. The junction member has a central collar for slidably receiving therein a vertical standard which carries a horizontal workpiece support bar. The junction member carries hand-operable locking means for cooperating with the standard and collar for securely locking the standard in a selected position.