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The Stark Company, originally of 222 Moody Street, Waltham, New England, U.S.A., bear an important name in the history of American close-tolerance engineering, for the firm were almost certainly the originators of the Precision Bench Lathe - as eventually made by a variety of firms including: Derbyshire, Levin, Bottum, American Watch Tool Company, B.C.Ames, Hjorth, Potter, Pratt & Whitney, Rivett, Wade, Waltham Machine Works, Wade, Pratt & Whitney, Rivett, Cataract, Hardinge, Elgin,, Remington, Sloan & Chace, and (though now very rare) Ballou & Whitcombe, Frederick Pearce, Sawyer Watch Tool Co., Engineering Appliances and Fenn-Sadler. Stark's claim as originators of the type was bold and unequivocal (and printed on all their sales catalogs), with the first examples being built by John Stark personally in 1862, well before any of his competitors - who were also mostly from the Waltham area. A special section of the Archive, assembled from literature of the 1870s, has been devoted to these very early and important Stark machines. The company were also famous for their watchmaker's lathes and also built a wide range of specialised machinery and tools for use in watch and clock-manufacturing and repair plants. Eventually to be made in six models - based around four different beds and headstocks - the Stark precision bench lathes were available with swings varying from 5.875 " to 12" and collet capacities from 0.25" to 1.25". Incredibly, production continued well into the 1950s, with small advertisements for their Series 400 and variable-speed underdrive No. 4 and 41/2 and bench-mount No. 3 precision plain-turning lathes making an incongruous appearance in the machine-tool trade press. Although Stark have now disappeared the American tradition of very high quality precision plain-turning lathes is continued into the 21st century by both the Derbyshire and Levin companies. The basis of all early models was a bed with bevelled edges and a single central T slot that located the headstock, tailstock and fittings such as a compound slide rest or hand T-rest. However, at the heart of the lathe's accuracy was a superbly-made, high-speed headstock spindle and bearing assembly based on a design already standardised for watch lathes where a hardened, ground and lapped spindle ran in glass-hard steel bearings - a system which represented the very best use of the materials and manufacturing techniques available in the late 1800s. The spindle and bearings were originally advertised as being manufactured from "English steel" - almost certainly a reference to crucible steel, the contemporary (Huntsman) method of producing small quantities of high-quality metal with tightly-controlled properties. The headstock design continued unchanged until the late 1920s when the option of precision ball bearing spindles was offered, at first to special order - and then only recommended by the makers for applications where very high speeds had to be sustained for long periods. The Stark headstock spindle was machined with both an internal taper, against which draw-in collets could be closed down onto bar stock by the action of either a simple "screw-in" draw tube or, for production work, a lever-operated closer. Unlike some makes an external thread onto which chucks, faceplate and other fittings could be screwed was also provided. A 3-step flat-belt headstock pulley was arranged so that the smallest diameter was immediately behind the spindle nose - on ordinary lathes it is usually the opposite way round - that allowed the all-important front bearing to not only be made as large as possible but also to be surrounded by as greater mass of supporting metal as possible. The design also made it easy to provide one or more rings of indexing holes that could be engaged by a pin passing through a boss cast into the left-and headstock wall - in exactly the same manner as employed on a watchmaker's lathe. The compound slide rest was held to the bed by a T-headed bolt engaging in a slot running down the underside of the cross slide. Beautifully-made, superbly-finished and with conical-face micrometer dials most Stark compounds had a T slot machined into the right-hand face of the cross slide so that front and rear stops could be mounted to make repetition work easier. A feature unique to Stark (on later lathes) was the mounting of the ring carrying the micrometer-dial zero mark on two rods attached to the inner casting; not always visible in photographs they can just seen in the illustrations of this page. The tailstock, like that fitted to most precision lathes, carried a barrel (spindle) that was fully supported by the surrounding casting, even when fully extended - although this feature was missing from the very earliest lathes. As John Stark was also prominent in the design and development of watchmakers' lathes, he may well have invented, amongst other items, the split collet (or "chuck" as they were originally known). Research into early Stark watchmakers' lathes and attachments is proving particularly difficult and if any reader can help with catalogs, photographs of lathes, or other information the writer would be very pleased to hear from them..
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