|
Famous for their very high-quality toolroom lathes, the English Holbrook Company, concentrated mainly on popular and hence profitable medium and larger-sized backgeared and screwcutting models - although they also made a superb, almost-Rivett-like precision bench lathe, the Model B No. 8 and it's companion, an advanced, electronically-controlled lathe introduced during the 1940s, a larger plain-turning lathe and the small, 31/2-inch centre-height by 161/2-inches between-centres precision plain-turning model shown below. The latter, designed using principles first established in American by Stark in 1862, when they had used scaled-up watch-lathe technology - both headstock spindle and bearings in hardened and lapped steel together with a flat-top, bevel-edged bed - to produce their much-copied and long-lived "Precision Bench Lathe." Thus, the little Holbrook joined a specialist, though crowded market, and one largely dominated by imports from the USA and Europe, amongst whom the better-known were: Levin, Bottum, American Watch Tool Company, B.C.Ames, Bottum, Hjorth, Potter, Pratt & Whitney, Rivett, Wade, Waltham Machine Works, Wade, Pratt & Whitney, Rivett, Cataract, Hardinge, Elgin, Remington, Sloan & Chace, W.H.Nichols, Crystal Lake and (though now very rare) Bausch & Lomb, Frederick Pearce, Van Norman, Ballou & Whitcombe, Sawyer Watch Tool Co., Engineering Appliances, Fenn-Sadler, "Cosa Corporation of New York" and UND. All these lathes were intended for use by both skilled operators turning and grinding one-off parts and (equipped with a range of suitable accessories) for small-batch production work. Hardened, ground and lapped, the 13/16-inch bore headstock spindle ran in adjustable steel cone bearings (a proven and economical way of providing high speeds and long life) and was driven by a 1-inch wide belt running round a 3-step cone pulley with diameters of 3, 37/8 and 43/4-inches. Two rings of indexing holes were drilled in the outer face of its largest diameter with an unusually robust indexing pin mounted eccentrically and able to be rotated in its housing to allow either ring of holes to be picked up instantly. There was no spindle thread and the only way of holding parts or accessories was by using collets or items (such as centres) mounted on a collet fitting. Continued below: (Read: An Apprenticeship at Holbrooks)
|
|