Manufactured by A.u.W.Busch KG Maschinenfabrick of 582 Gevelsberg, I. Westf. in Germany, Busch milling machines were of a special, if not to say unusual design. A range of models was offered, some intended for ordinary milling work, others of special construction advertised as "Vertical Keyway Milling Machines" and ones intended for work that involved machining "Square, Rectangular and Rhomboid Contours".
Typical of the models offered was the FSU, this being built in two sizes as the models 350 x 500 and FSU 350 x 500/500, the numbers referring to the width and length of their tables in mm. In addition to the usual table movements, the machines had a huge vertical head that could be tilted 45 degrees each side of upright and moved both longitudinally and in traverse using narrow, plastic-lined square guideways machined into the top face of the massively heavy base.
Running in The head drive was hydraulic and variable in speed, the Model 350 x 500 with 250 mm (9.9 inches) longitudinally and 150 mm (5.9 inches) in traverse and the Model 350 x 500/500 with 560 mm (22.1 inches) and 1000 mm (39.4 inches) respectively. While spindle speeds were infinitely variable they were not continuous from fastest to slowest but arranged in five groups that gave rates of 110 to 660 r.p.m.; 200 to 1200 r.p.m.; 300 to 1800 r.p.m. and, with one shifting of the drive belts over the 2-step drive, 110 to 4000 r.p.m.
To allow an owner to choose the most appropriate table for his particular requirements, the makers offered a choice of three, all 350 mm wide by 1100 mm long with three T-slots - the same fittings being offered on both the smaller and larger models. Two tables were hand-operated in every direction, one a plain non-swivelling type, the other able to be tilted 10 degrees backwards and forwards and swivelled 10 degrees on its vertical axis. The third table, non-swivelling or tilting, was power driven longitudinally, in traverse and vertically and incorporated an electrical system that allowed four methods of control: by hand to set up a job; move to the right and stop on the right; move to the right and return to the start position and planetary milling for continuous work. As the head could also move in the same relationship to the table it was possible to machine surfaces at right angles to each other - or even in a square form - without any resetting.
Table travels on the 350 x 500 machine were 500 mm longitudinally, 250 mm in traverse and 310 mm vertically. Corresponding figures for the 350 x 500/500 model were 550, 300 and  300 mm. On power-feed table models the number of rates totalled nine in all directions with rapids incorporated as well - the latter fitting also being included as standard on the vertical travel of machines fitted with hand-operated tables.
Flange mounted against the rear of the head, the main 4 h.p. motor drove through a P.I.V gear transmission and then across the top of the head, by V-belt,  to the cutter spindle. Supported in a pair of high-precision, adjustable taper-roller bearings on its nose, the spindle could hold its cutters in either the maker's own spring collet chuck or on a sort taper with a draw-in action.
Hydraulics were powered by a 1.1 h.p. motor and the table's electric drive by one of either 0.5 or 1.5 h.p.
Busch made a variety of milling and vertical keyway machines, some of which are shown below.