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Coronet Miniature Precision "Ruby" Lathe

Coronet Precision Lathe Home Page   Jewel Lathe


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Coronet Instruction Literature is available, please email for details




Described by the makers as The Watch and Clockmakers Lathe and Multi Propose Machine, the tiny, 1.5" centre height Ruby had a headstock casting that doubled as a mounting foot with a bolt-on motor as part of the optional equipment. However, as the latter carried just a 2-step pulley (when a 4-step could have been specified for only a few pence extra), the speed range was severely limited. The headstock pulley was overhung, an unusual and rather brave design decision for a precision lathe where the tradition of super-accurate bearings, of hardened steel, honed and lapped to perfection, with the pulley carried between them, had been established for over 80 years. By coincidence, the same decision had been reached by the English Pultra Company on their new range of 17/50 and 17/70 models, also announced in 1946/7.
To allow the Ruby to function either as a lathe or a precision drilling and milling machine, it was mounted on a heavy cast-iron base plate formed with a post socket at one end.  With the lathe set as a drill, the bed was up-ended, dropped into the socket and held in place by a long through-bolt. The tailstock, already provided with a lever-action feed (by the simple expedient of peg passing through a slot cut through the top of the casting) was fitted with a collet-retained faceplate that acted as a drilling table - while the (optional-extra) compound-slide rest assembly could be pressed into service as a co-ordinate table for vertical milling. In order to provide the greatest versatility, the headstock was available with a choice of two cartridge spindles: one for ordinary work with an adjustable tapered bronze bush at the front and a single ball race at the back (an arrangement also used, in a non-cartridge form, on most of the Company's wood lathes) and the other, a high-speed unit, with ball races at both ends. The assembly (not unlike that used on the first Emco Unimat lathes from 1953 and resembling a bicycle hub) was clamped into the headstock by a single lever closing down a slot in the casting; hence it could be removed very easily and swapped over. With a 0.314" bore and a  5/8" x 26 t.p.i. nose thread, the spindle was designed, like the tailstock, to accept draw-in 8 mm collets.
Beautifully painted in
black ripple enamel (crackle-black, a popular finish at the time and used to denote a quality product ) and with all the locking rings and adjusters beautifully knurled, the basic Ruby retailed for 18 : 18s : 6d without a motor (for comparison a backgeared and screwcutting ML7 was first listed at 36). Complete and ready to run the price rose to 24 : 18s : 0d. A compound slide was an extra 9 : 18s : 6d, a 2.5" precision 3-jaw chuck 6 : 15 : 0d, wire collets 7s : 6d each and stepped collets 12s : 0d. Supplied as standard with each machine was the cast-iron base plate, a hand T-rest, faceplate, driving pin, collet draw-in tubes for headstock and tailstock and one pair of precision centres mounted on collets. An interesting comparison can be made between the Ruby and the German Saacke miniature universal machine of the early 1950s - through the latter would, no doubt, have cost several times as much.
Using many components of the Ruby, including the complete headstock and tailstock units and a bar-bed, the "Jewel" was arranged conventionally with small splayed feet and a carriage driven by an overhung leadscrew running down the front face of the bed. A single swivelling tool slide was fitted with the whole machine looking remarkably like the larger but much cheaper and less desirable Velox from the early years of the 20th century. .

Coronet "Ruby" arranged as a lathe

Coronet "Ruby" arranged as a precision drill with lever-action tailstock supporting the work table




Coronet Ruby

Coronet Ruby arranged as a drill

Component parts of the Coronet Ruby headstock spindle cartridge

Coronet Ruby headstock cartridge dissembled




Coronet Precision Lathe Home Page   Jewel Lathe


Coronet Wood-lathes Home     
Coronet Instruction Literature is available, please email for details


email: tony@lathes.co.uk
Home   Machine Tool Archive   Machine-tools Sale & Wanted
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Coronet Miniature Precision "Ruby" Lathe