Developed from the Type 51 and Type 52 of the mid 1940s, the Schaublin 53 Universal High-precision Milling Machine was an expensive proposition that, even so, found favour around the world as a highly versatile, wonderfully accurate and reliable machine tool. Heavily built - it weighed 1700 kg - the Type 53 was based on a patented design and used a massive (ventilated) main column and foot in cast iron to house the head and coolant motors, the spindle drive gearbox (complete with a combined double-plate steel-on-steel clutch and brake unit by Stromag), the table-feed gearbox, the special V-belt driven oil-mist mechanism (a compressor and atomizer) for lubricating the horizontal milling-head cylinder, all the electrical switchgear and, formed as part of the base, a 50-litre (11-gallon) coolant tank.
While the column, drive system, knee and table were conventional enough, the head arrangement was, possibly, unique and gave the machine an ability to switch quickly between vertical and horizontal modes. Driven by bevel gears, the various heads were carried on the end of a sliding horizontal cylinder 240 mm in diameter that could be rotated through 360°, locked at 15° intervals and with an in-and-out travel of 300 mm. The spindle nose was an ISO 40 (the steep taper of which allowed the easy release of tooling) to specifications VSM 33931, size 44, or DIN 2079, size 40 with a positive, 2-key drive. The fitting was large enough to take a variety of useful adaptors down to 1, 2, 3 or 4 Morse and also carry (in suitable holders) Schaublin Type W20, W25 or E25 collets. Fitted with a 4 h.p. motor running at 1500 r.p.m., both standard and high-speed heads were available, each driven from the main spindle. The former, with its fixed quill, had eighteen speeds of 38, 48, 60, 72, 92, 115, 140, 172, 212, 270, 340, 422, 515, 650, 800, 970, 1220 and 1510 r.p.m. and could be rotated on the end of the horizontal housing with an eccentric lock that gave precise clamping every 30 and 50° while also allowing any intermediate position to be set. Originally available in two versions - one with and the other without a fine-feed to the 80 mm travel quill (types 1120 and 1100) - the 33 kg high-speed head was designed to take Schaublin E25 collets and had the same number of speeds as the standard head but spanning 150 to a usefully high 6000 r.p.m. Both versions had a quick-action drilling lever and, as an option, a most unusual accessory - automatic power feed to the quill driven by a flexible cable from a worm-and-wheel gearbox clamped to the right-hand end of the table's feed screw.
Spindle speeds, provided by a gearbox that had both oil-bath and spray lubrication (the latter by an immersed piston pump) were selected by a Cincinnati-type rotary control on the right-hand face of the column with every half-turn of the crank, in either direction, giving the next higher or lower rate with the dial automatically showing that selected. Lubrication of the horizontal cylinder and head was by pressure-fed mist, the benefits claimed including a cooling effect and an improved and more uniform distribution of the oil.
When switching to horizontal milling, instead of having to lift and mount a heavy overarm and drop bracket the operator simply pulled a pair of 50 mm diameter ram supports out from the face of the head with the cutter arbor (supplied in a number of lengths and diameters) being socketed into the horizontal spindle nose. While not as rigid as a more conventional system for most purposes it was, according to experienced users, perfectly adequate - especially if the optional twin bracing bars between arbor and saddle were fitted.