Designed to compliment Schaublin miniature precision lathes made during the 1930s (the SV65 and SV70), the very rare SV11 milling machine was engineered to accept components from both, including headstocks, tailstocks and a good number of items from their accessory range.
A miniature version of a design concept probably first employed by Deckel in 1917 (and developed by them to become, in the early 1930s, the well-known FP1), the SV11 was fitted with a head mounted on a sliding plate sitting on top of the main column together with a vertical front table machined with two curved T-slots that could accommodate a variety of fittings. The table could be moved horizontally on its carrier plate by screw or lever feed through some 90 mm (3.54") of travel and, by screw action only. through 80 mm (3") vertically on ways machined into the front face of the column.
By juggling the choice of heads and tables, and utilising other accessories, a skilled technician was seldom defeated in his attempts to produce the most complex of milled and drilled components - and all to a very high standard of accuracy.
A tiny machine, needing a space only 500 x 450 x 500 mm (20" x 18" x 20") the SV11 was fitted as standard with a right-angle table that could be inclined 10° each side of horizontal. A number of different tops could be mounted, held in place by two T-bolts tightened by through-cams whose heads finished in circular bosses protruding through the table's front face. A popular fitting was a top, able to be swung 5° each side of central, some 350 mm (13.8") long that was formed with the same section as the bed of the Schaublin SV65 and SV70 lathes - so allowing the headstock, tailstock and other bed fitting from those lathes to be attached. Another useful attachment was a simple rectangular table with three T-slots that could accept all the usual angle plates, machine vices and other clamping arrangements for general work. Other accessories were the semi-circular table (Accessory No. 24) usually equipped with a short slide that could be rotated through 180° horizontally and able to mount a number of accessories including a special lathe-like headstock and the indexing quill holder Type 91. For work in the vertical plane Accessory No. 28 was offered, an inclinable quill holder whose support casting was held in the table's curved T-slots. It carried a quill (Accessory No. 91), to take Type W collets, and was indexed by a 60 tooth division plate and pawl assembly. Although not listed, it is likely that two other versions of the quill holder were available, one with worm-and-wheel gearings (as used on the SV12) and a type constructed as a fixed unit with a base able to be attached to one of the horizontal tables.
At least two versions of the milling head were made, one being rounded in form and the other more rectangular and machined on its top surface to take a horizontal overarm and drop bracket to support the end of a milling arbor. Weighing around 40 kg, both heads took, as standard, a Type W collet with a maximum through bore of 12 mm - however there was the option (which can rarely have been exercised) of a smaller spindle with a 10 mm bore. Mounted on the side was a 3-step pulley, with diameters of 40, 56 and 72 mm, its drive being turned through 90° by bevel gears at a step-up ratio of 2:1. Before being locked down the head could be positioned on the slide forwards or backwards through 130 mm, the slide itself having a travel of 70 mm by lever or screw. The head could also be mounted on an angle bracket to bring its spindle vertical; unfortunately the lack of a quill feed limited its usefulness for sensitive, high-precision work, all up and down feeds being by lifting the table.
Two types of drive system have been identified, one for stand-mounted and the other for bench models. The former was a tall unit, mounted on ears bolted to each rear edge of the stand with the upper section pivoting on its lower bracket to compensate for the in-and-out movement of the head; a simple rod and split-socket joint was used to set the belt tension. The unit not only drove the horizontal and vertical heads, but a table power-feed attachment and a coolant pump as well. With power provided by the recommended 3/4 to 1 h.p. motor the eight spindle speeds ran from a low of 100 through 160, 240, 370, 470, 720, 1100 to a high of 1700 r.p.m. Table feed rates were listed in two ranges, the first being 7.5. 14. 24, 43, 65, 113, 200 and the second 0, 57, 99, 175, 138 and 260 - all in mm per minute. For bench models an integral countershaft was used with a 1/5 h.p. motor bolted to a plate on the back of the column and driving horizontally to a countershaft that pivoted from a boss on the right-hand face of the main body. The unit consisted of a pair of lower and upper pulleys separated by a shaft into which socketed, at both end, castings holding the pulley bearings. The unit, which gave spindle speeds of 225, 380, 675, 1040, 1800 and 3100 r.p.m., was stabilised at the top by a bar, hinged from the left- hand face of the column, with the round drive belts tensioned by a left-and-right-hand-threaded turnbuckle.
Although a fine machine, and a delight of miniature machine-tool engineering, the SV11 was somewhat limited in its versatility and, after Aciera introduced their much more accomplished range of miniature millers (the F11, F12 and F1), by the end of WW2 it had been quietly dropped.
If you have a Schaublin SV11, the writer would be very interested in hearing from you.
Si vous avez un Schaublin SV11, l'écrivain serait très intéressé à entendre parler de vous.
Wenn Sie eine Schaublin SV11 haben, würde der Schriftsteller sehr daran interessiert, von Ihnen zu hören...