Manufactured from the early 1930s (it first appeared in the catalogue for 1933) most Schaublin SV12 millers were made during the 1940s and 1950s - though a few were constructed in the 1960s with a taller (200 mm higher) column to give more room under the cutter. Sales literature for many years refers to the miller as both the SV12 and 12 - though the machines illustrated appear to be the same and have identical specifications. One of a series of similar Schaublin models, the SV12 was offered (pre-WW2) alongside the rather different and much smaller Schaublin 11, with an interloper in the form of the 1940s Schaublin 11-A and 11-B. Like all of its type*, the SV12 was designed to use a wide range of accessories including many from the Company's existing range, the top surface of the standard table being, for example, identical in form to the bed on the Company's 90 and 102 precision lathes (though as the quill holder and headstock are 90 mm centre height, the compatibility with the 102 is limited). If your toolroom was already equipped with Schaublin machine tools, this facility would have represented a useful saving. Although similar in general layout to the traditional form of precision universal miller as made by, amongst many others, Deckel, Maho and Thiel, the SV12 was smaller, lighter (450 kg) with much shorted table and head travels and a more restricted accessory range, especially as regards head units. In its basic form the miller carried a sliding horizontal milling head, with oil-bath lubrication, held on prismatic ways machined into the top of an intermediate plate that ran in V-edged ways milled into the top face of the main column. The No. 4 Morse taper spindle ran in a double roller race at the front and a pair of opposed ball races at the back, the drive coming from a side mounted shaft (supported in taper roller bearings) driven by a 2-step V-pulley - the drive being turned through a right-angle by bevel gears. As the head moved forwards and backwards, this arrangement allowed the belt to work with only a minimal change in tension. Instead of being locked into a fixed position, the head could first be adjusted through a range of some 80 mm, front to back, on its intermediate plate - with some 120 mm of travel then available by either a fine-feed screw or a lever using rack-and-pinion gearing. Instead of removing the head to fit accessories, gearing within it allowed others to be mounted on top, the design having the advantage of providing extra clearance between cutters and table. The three items that could be fitted were: a vertical head, a slotting head and an overarm and drop-bracket to support the outer end of the horizontal cutter arbor; - the top being covered by a cosmetic plate when the accessories were not in use. It is known that, over the years, some changes were made to mechanical details concerning the head and its drive system: the headstock bearings and arrangement of the headstock gear oil bath altered as well as the horizontal drive shaft in the vertical headstock. Power came from a single or (optionally and preferably), a 2-speed (1/1.35 h.p. 710/1420 r.p.m.) motor fitted with a 2-step main drive pulley and mounted on a hinged plate inside the cast-iron stand, a space it shared with the 0.1 h.p. coolant pump and 25 litre tank. From the motor the drive passed to a pivoting arm and from there, via a 2-step pulley, to the horizontal head, both drives being by V-belt. The purpose of the separate arm was to hasten speed changes, the arm being formed with a slotted section through which passed a locking bolt; upon releasing this the arm was pulled upwards by a long coil spring, the belts swapped from pulley to pulley and the arm then pressed down (using a handle protruding from the end of the arm in line with the pulley spindle) and locked. With a 2-speed motor fitted and using the high and low-range 2-step pulley arrangement, the twelve horizontal spindle speeds ran from a slow of 100 through 150, 200, 290, 300, 450, 580, 700, 900, 1100, 1400 to a high of 2000 r.p.m. When fitted with the optional No. 210 swivelling vertical head with internal, step-up gearing, these became: 120, 183, 240, 356, 366, 554, 712, 860, 1110, 1350, 1720 and 2700 r.p.m.
A second 4-step pulley on the motor shaft drove a countershaft that was used to run the table's horizontal power-feed gearbox, a V-belt passing vertically upwards to a beautifully constructed, bevel-gear equipped, lever-controlled reversing mechanism bolted to the vertical table's right-hand face.
Like other machines of the same format, the Schaublin was fitted with a vertical table on it's column's front ways; with a relatively limited travel horizontally of 200 mm (by hand or optionally under power) and vertically of 200 mm (by hand only) this could carry, secured in two semi-circular T-slots, a variety of fittings including a standard-fit 450 x 200 mm fixed rectangular table that was strongly braced with three vertical ribs and fitted with three 11 mm T-slots on 60 mm spacing. This table, rather strangely, could be tilted just 5° to the left or right from level, an amount so insignificant as to be almost useless and, in addition, needing the operator to devise some precise method of setting it exactly horizontal, there being only degree engravings and no maker-fitted mechanical device (a ground tapered pin for example), to accomplish this. In turn the fixed rectangular table could mount various other fittings: a full-length plate (held by two T-bolts with cam-action tightening from the front) with the same top profile used on the bed of the Company's 102 lathe and able to be swung ± 5° from parallel; a plain rectangular table; a table with a semi-circular top and a rotary circular table. With the standard table removed and the vertical surface exposed, it then became possible to bolt on a small universal table that tilted left and right and up and down, an inclinable quill holder (designed to take a variety fittings in its nose, including collets) or indeed, any special device or construction made by the owner for one-off jobs. Screw-feed of all travels - tables and head - was measured by large, very sharply engraved zeroing micrometer dials.
In its basic form the miller was only capable of using a simple stub cutter, hence obvious and desirable additions included, amongst others, the overarm and drop bracket to support the outer end of a horizontal milling arbor; the No. 201: Swivelling No. 4 Morse vertical head that could be swung 90° in each direction from upright - unfortunately this lacked a quill feed but was supplied with reduction bushes to accept W20 collets and 1, 2 and 3 Morse taper shanks; a slotting head, No. 12/747, that was inclinable 90° each side of vertical, a stroke capable of variation between 0 and 46 mm and six rates of 50, 75, 135, 210, 335 and 525 per minute and the No. 12/747 dividing headstock consisting of the No. 12/17 fixed quill holder, 12/102 Quill (with a threaded-nose spindle able to take W20 collets, a collet draw bar, a spindle-nose protector, a male centre, the 12/110 dividing plate, 12/108 pawl and spring and the No. 12/20 tailstock. All these, and other items, are shown below.
In operation, the SV12 is reported as being very accurate and versatile, though the limited range of table and head movements does restrict its usefulness and having all the controls of the left-hand side of the machine does not suit everybody. Unfortunately the SV12 was up against strong competition from Aciera and, as just the tiny SV11 was outperformed and outsold by the much superior Aciera F1 (its predecessors being the F11 and F12) the SV12 gave best to the Aciera F3
If you have a Schaublin 12 the writer would be interested to hear from you..