email: tony@lathes.co.uk
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Holbrook Lathes
31/2" Precision Bench Lathe

Instruction & Maintenance Manuals are available for many Holbrook lathes

Holbrook Model B No. 8   Holbrook Model B No. 9   Holbrook Model T Lathes
Model 5P Precision Plain Lathe  Holbrook Minor 1960s - 1980s
An Apprenticeship at Holbrook   Holbrook Edgar Lathe   Serial Numbers
Holbrook Model C   Holbrook Type B13, B17 & B21

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, 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, WadePratt & 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 1
3/16-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 the end of a collet fitting.
Continued below:  (Read: An Apprenticeship at Holbrooks)

Continued:
Strongly constructed, the compound slide rest was featured a top slide that could be swiveled to any angle; its base, formed as a large circular boss, was engraved with especially clear divisions to 45-degrees each side of zero. With no feed available along the bed, like all plain-turning precision bench lathes, the top slide had, of necessity to be given a relatively long travel - but in this case not as long as it should have been at 4
1/2-inches.
Although they read to 0.001'', the micrometer dials were tiny, even by the standards of the day, and fitted with the type of twin, closely-pitched, knurled finger-grip rings more commonly found on watchmakers' lathes. Supplied with the lathe to compliment the slide-rest was a bed-mounted hand-turning rest with both long and short Tees.
Departing from standard  precision bench lathe practice, the tailstock did not have its spindle supported along its entire length when fully extended - but was fitted with a micrometer dial and self-eject for the No. 1 Morse centre.
Whilst not in in the Stark or Ames class for the variety of accessories offered, Holbrook nevertheless contrived to list a number of useful items including a range of ordinary and large-diameter draw-back internal and external collets and the necessary closers; a vertical milling slide with both an indexing unit and a high-speed drilling & grinding spindle; a fixed steady; fixed and swiveling grinding heads and a 7-inch diameter faceplate that could be had in plain, T-slotted, or tapped-holes versions - or even lead faced for lapping work. The usual type of Precision Bench Lathe screwcutting attachment was also listed with the changewheels carried on a proper adjustable bracket and the drive to the top slide through a telescopic shaft with a single keyway.
In order to generate very precise pitches, the lathe was available with a thread-chasing attachment driven by 2:1 reduction gearing.  The chaser (threading tool) was carried on a bar slideway running through a long tunnel bored through the back of the headstock casting. The toolholder was fitted with a micrometer dial and screw-adjustable depth stop, while a tapered stop on the feed mechanism could set to halt the cut at any point. An unusual and timesaving feature of the Holbrook unit was the provision of a weight to automatically lift the chaser from the job on disengagement and return it to the start position. Happily, with the chasing assembly swung back out of the way, the headstock functioned as normal for ordinary turning jobs.
For production work Holbrook offered a complete range of equipment to turn the lathe into a miniature capstan lathe amongst which the main units were: a larger headstock that allowed the use of collets up to 1-inch capacity and almost certainly the mounting (as with the standard head) of both draw-tube and lever-operated collet closers; a bed-mounted 6-station capstan unit to take 3/4'' tooling and a cut-off and forming slide with front and rear toolposts.
To mount the lathe either a pair of simple legs ("standards") and chip tray, both in cast iron, were available or, at considerably extra cost, a rather superior mount with different legs, a wooden tool tray and an integral high-speed ball-bearing countershaft countershaft with fast-and-loose pulleys under foot-pedal control and an additional round-rope "overhead" drive to power the grinding and drilling spindles that this sort of lathe was expected to carry mounted on its top slide.
When equipped for production a special countershaft was supplied that enabled stop, start and speed changes to be made by foot-pedals operating wire links. 
Complete with a compound slide rest the lathe weighed, in basic form, a substantial 200 lbs..

Power-feed and screwcutting attachment. The changewheels were mounted on a proper (adjustable) bracket and drove the top slide through a telescopic shaft carrying a single keyway. The attachment allowed a wide range of feeds and threads to be generated

For very precise, short-length screwcutting the lathe was available with a thread-chasing attachment

Swing-round grinding attachment - driven from a large pulley carried on the "overhead". This was a special unit that, unlike the toolpost-mounted grinding and milling spindle, was carried on its own bed plate

When mounted on standards (cast-iron legs) it was possible to adjust the working height by fitting the maker's blocks under each bed foot

For production work Holbrook offered a complete range of equipment to turn the lathe into a miniature capstan lathe. Shown here are the bed-mounted 6-station capstan unit to take 3/4'' tooling, a "cut-off and forming slide" with front and rear toolposts and a lever-action collet closer

Equipped in a way that would almost certainly have tripled the cost of the basic lathe the little Holbrook is shown here mounted on the maker's stand with wooden tool tray, a built-on high-speed ball-bearing countershaft with fast-and-loose pulleys under foot-pedal control and a thread-chasing attachment complete with its revolving master-thread and collet stand

Grinding attachment with internal extension spindle

Traverse grinder spindle for internal work. The operator simply gripped the round knob on the end and moved the wheel in and out as necessary

For use with the ordinary lathe a fast-running, 2-speed ball-bearing countershaft assembly was available that incorporated both fast-and-loose pulleys and an additional round-rope "overhead" drive for the grinding and drilling spindles

When equipped for production a special countershaft was supplied that enabled stop, start and some speed changes to be made by foot-pedals operating wire links

Foot pedal to control the capstan-lathe countershaft unit

email: tony@lathes.co.uk
Home   Machine Tool Archive   Machine-tools Sale & Wanted
Machine Tool Manuals   Catalogues   Belts   Books  Accessories

Holbrook Lathes
31/2" Precision Bench Lathe

Instruction & Maintenance Manuals are available for many Holbrook lathes

Holbrook Model B No. 8   Holbrook Model B No. 9   Holbrook Model T Lathes
Model 5P Precision Plain Lathe  Holbrook Minor 1960s - 1980s
An Apprenticeship at Holbrook   Holbrook Edgar Lathe   Serial Numbers
Holbrook Model C   Holbrook Type B13, B17 & B21