Abstract: A workcenter (10) comprises its supports (14a,b,c) which each carry a carriage (24a,b,c) movable along the supports by motors (30a,b,c) under central computer control (41). Each support is an aluminium extruded U-shaped section having four tracks (28) comprising steel strips (27) in slots (29). The carriage is likewise extruded having undercut slots (83) receiving the heads (92) of axles (90) which have eccentric stubs (96) on which bearing wheels (26) are journalled. Four wheels are so-mounted at each end of the carriage. The workcenter is adaptable between different modes of operation; overhang or cantilever by virtue of the profile of the supports.