Abstract: Tubular frame pieces, with generally a welded construction, provide a sturdy support for mounting a heavy duty vise or other heavy-duty tool. Convenient changeability is provided from an erect working condition to a compact condition for transport or storage, even though such convenient changeability would not be expected for such heavy duty apparatus. A rear leg frame assembly and a front leg frame assembly are rotatably carried by transverse bars of a base frame. Temporary or partially-supported condition is provided for ease of erection, but a positive erection-holding feature is also provided. Extender bars are optionally provided for carrying ancillary features in addition to the mounting table for the vise. A base frame is provided with wheels, the wheels being movable to a floor-engaging position for ease of mobility, and a retracted position for maximum sturdiness.