Carstens made their first milling machine in 1928  with the Model  HVF 400-130 vertical shown left being as made during the 1930s and 1940s. Typical of its time, the miller carried its drive motor on the back from whence it drove, using a flat belt running over a pair of adjustable jockey pulleys mounted at the top rear of the column, to the 23 mm bore, No. 3 Morse taper headstock spindle (though some machines have been found with an as-yet-to-be-identified fitting. Heavily nitrided and ground, the spindle ran in adjustable taper roller bearings and could accept draw-in collets up to a maximum capacity of 20 mm. A useful touch was the provision of a threaded spindle nose to accept chucks - the thread perhaps being the same as used on the Company's D-Series lathes.
With 8 spindle speeds available from 80 to 600 r.p.m.- and bearing in mind the limited amount of room to fit a cone pulley - it is likely that a 2-speed motor would have been fitted. The 500 x 130 mm table was power-driven, with rates of feed from 16 to 90 mm/min. Unusually, the miller was fitted with both an elevating knee and a vertical way to adjust the position of the head--though the latter must have been severely limited by the need to accommodate the belt drive.
Cutters were held in draw-in collets, the maximum capacity being 20 mm.
Do any Carstens milling machines survive? If you have an example, the writer would be very interested to hear about it.