Stevens Page 2
Today, if you are a professional or keen amateur watch or clock maker, one problem you will face is finding a suitably small and very accurate milling machine. While there are numbers of very cheap machines available from the Far East, these are all built down to a price and intended for light model engineering - and not one of then even begins to approach either the sophistication of construction, or delicacy of control, as found in older classic examples by, for example, Wolf Jahn or Aciera. To meet this need, Stevens Precision of London now offers a specially-constructed miniature precision milling machine constructed along traditional lines that accepts a standard 8 mm lathe collet for cutter holding.
With a table five inches long and two inches wide (with travels of 2.5-inch on each axis) the machine is arranged with a tilting head, able to travel through 1.5 inches propelled by a screw or lever feed and with 6.5 inches of coarse vertical positioning available on the 20 mm diameter column. Running in either high-precision SKF ball-bearing of the deep-groove type, or with traditional watchmaker type hardened and lapped plain bearings, the spindle can be driven safely at speeds of up to 6000 r.p.m. - sufficient for the very smallest of cutters and finest of work. Made as a very rigid, one-piece box, after its external faces are finished the headstock is assembled with its spindle and the end face and collet fitting of the latter ground and lapped in place. Drive is by a round belt that passes over a pair of alignment jockey pulleys, exactly like the system employed on Leinen and BCA miniature jig-boring and milling machines.
Table, cross slide and head ways are all of the traditional 60?V-type with some considerable trouble taken to make their movements as smooth as possible. All ways - and even the gib strips - are lapped to a perfect fit and all sliding elements are fitted with a row of very closely-spaced gib-strip adjustment screws - though the lapping renders their use as a means of setting a clearance largely superfluous. Feed-screws, of 5 mm diameter and 1 mm pitch, pass though a pair of tiny ball races where they enter the support tube, with the thread running through bronze nuts fitted with a clever and very effective spring-loaded anti-backlash device.
Although sold as a complete machine the Stevens can, very handily, be easily dismantled to provide a self-contained compound table together with a "headstock" adaptable to other purposes such as polishing, or for use as a high-speed grinding or milling head when mounted in the toolpost of a lathe.
Each machine can also be specified - or even customised - to a customer's exact requirements, or bought as-is. Other products include: balanced handwheels in a variety of sizes, miniature machine vices, a watchmakers' swivelling vice and engraved micrometer dials. One-off commissions can also be undertaken to create, modify or adapt watch or clock-making tools to a customer's own designs. By around April 2019 a heavily revised, more robust model of Stevens will be introduced. For further details, please contact John on: 07831-877240 (from overseas: **44-7831-877240)