email: tony@lathes.co.uk
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George Adams of London
GA 21/2" Precision Plain Lathe

GA 21/2" Lathe Page 2   GA 21/2" Lathe Page 3

George Adams Home Page

GA Lathe Model 21/2  

G.A. Watchmakers' Lathes 

G.A. Round Bed Lathe

3.25" & 4.75" Screwcutting Lathes Models D, E, F, G & H

4" & 5.25" 4" & 5.25" Screwcutting Models A, B, L, KF1 and CL

3.25" & 4.75" Precision Lathes Models D, E, F, G & H

2.75" Screwcutting Lathe Model CS

Advertisements 1930

GA 21/2" Precision Plain Lathe

Watchmakers' Lathes

Portass-built Mk. 5 Lathe Photo Essay


Beautifully made, the little George Adams 21/2" centre height precision lathe has been a machine sought after by generations of amateur machinists - especially clockmakers - keen to get their hands on a genuinely high-quality product (though it must be said that the design quirks, present on nearly all George Adams's products, were present on this version too). Also found badged as the R.Kelly of Manchester & Liverpool, the lathe was almost certainly inspired by German Wolf Jahn practice with very small marks - usually saying just "Germany" in tiny letters -  sometimes being found stamped on various parts using that company's recognisable style. In addition the accessories also confirm such a connection, being constructed in an identical way and directly interchangeable with the Wolf Jahn originals. Normally sold in plain-turning form, the 21/2" could also be fitted with two types of screwcutting arrangement: the first, using a straight shaft direct from changewheels to the top slide was at odds with the normal practice of using a keyed and universally jointed shaft; the second consisted of a proper bed-mounted leadscrew - in which latter form it is particularly rare. Made for several decades, from approximately 1900 until the mid 1930s, it had a bed of typically English/German pattern, being flat on top with the location for headstock, carriage and tailstock formed by vertical flat shears between the two ways. An unusual feature was the mounting of the bed feet - they were simply bolted to rather ugly-looking lugs formed at each end of the casting. However, being finely machines on both top and bottom surfaces - and located on the machined underside of the bed - the feet did add slightly to the bed's stiffness.
Like all "Precision" George Adams lathes, the headstock of the 2
1/2" followed the well-established pattern for a high-quality "Bench Lathe*" of having bearings made from opposed , hardened steel cones that closed down on similar hard cones fastened to or formed as part of the spindle. Provided a supply of clean oil was maintained, this type of bearing proved capable of almost infinite life - some American lathes  (by Stark and Wade) having successfully absorbed over fifty years of commercial use without failure. The headstock spindle (or mandrel as it was then called) accepted a hardened, tapered insert that took standard 8 mm collets. This insert can, incidentally, be hard to see, being a very close fit within the 7/8" diameter, 20 t.p.i nose, and must be removed if use of the full spindle bore is required.
Designed to be driven by a round leather rope - or "gut" in popular contemporary parlance - the 3-step cast-iron pulley was locked to the spindle was a somewhat over-engineered (though delightful) collet-like  method where the smaller end of the pulley was turned parallel for a short distance and slotted with four equally-spaced slits; a large clamping ring was slipped over the slotted section and tightened by four screws until it closed down onto the spindle - the arrangement can clearly be seen in the pictures below.
Equally neat, though not unique - it also being employed by Rivett - was the method of securing the "balanced" ball-ended handles on the very long-travel compound slide rest; a long screw, with its slotted head moulded so as to blend in with the end of the ball, passed right down the stem of the cross piece to engage with the end of the feed screw. The design of the compound slide assembly was unusual, and incorporated some weaknesses; the feed screws were 25 t.p.i. with brass micrometer dials, finished, on early examples, with a double rim and traditional "rope" knurls, engraved with divisions of 0.002". The slide rest changed over the years with some being in proportion to the rest of the machine (with the expected lengths of travel) while other were noticeably different with considerably longer cross slides and more modern-looking micrometer dials. Unfortunately the top slide - which on all models had at least a useful 3 inches of movement -  had no degree marking for its swivel settings; and, equally disappointing for a quality lathe (though in line with later Schaublin practice), was the use of a long horizontal slot in the tailstock casting to act as a clamp for locking the (short) No. 1 Morse-taper barrel. The danger of the casting being over tightened, and broken off, was mitigated against (to some extent), by the provision of two adjustable stop screws that passed through the slot - one at each side of the clamping screw; the general arrangement of the tailstock slit can be seen in the third picture below.
An unusually  wide variety of accessories was available for the lathe enabling it to be used for grinding, screwcutting, precision sawing, milling and light production work.
Original colours used on George Adams lathes included plum red and emerald green.
*Including: American Watch Tool Company, Arrow, B.C.Ames, Bausch & Lomb, Benson, Boley, Bottum, Boxford, B.W.C., Carstens, Cataract, Cromwell, Crystal Lakes, CVA, Derbyshire, Elgin, Hardinge, Hjorth, Juvenia, Karger, Leinen, Levin, Lorch, Mikron, W.H.Nichols, Potter, Pratt & Whitney, Rambold, Rebmann, Remington, Rivett, Saupe, Schaublin, See (FSB), Sloan & Chace, Smart & Brown, T & L.M., U.N.D., Van Norman, Wade, Waltham Machine Works, Weisser, Wolf Jahn and (though now very rare), Frederick Pearce, Ballou & Whitcombe, Sawyer Watch Tool Co., Engineering Appliances, Fenn-Sadler and the "Cosa Corporation of New York.."

The standard GA 21/2 plain-turning lathe.

Screwcutting attachment driving through a straight shaft to the top slide - an arrangement at odds with the normal practice of using a keyed and universally jointed shaft

The maker's lever-action toolpost grinding attachment fitted neatly into the cross-slide T slot. The unit was very well built and incorporated a oil-bath gearbox to increase the wheel speed. Driven from an extension of the lathe countershaft the gearing allowed a work piece in the chuck to run at a modest 350 rpm whilst the grinding spindle rotated in the opposite direction at up to 12,000 rpm.

George Adams geared Toolpost Grinder - an expensive accessory at over half the price of the basic lathe.


GA 21/2F Precision Manufacturing Lathe. The Model F was supplied with a capstan unit mounted on the tailstock and a double-toolholder cross slide for forming and parting-off work.
The headstock was specially constructed to accept collets of a much greater-than-standard capacity - 11/16" in the nose and 9/16" pass-through - however, to achieve this within the confines of a 2.5" centre height and transmit enough power to make the enterprise worthwhile, the large-bore spindle had to run in such massive bearings that only a single wide pulley could be accommodated between them.

The Capstan tailstock  that could be fitted to all GA 21/2 lathes. The barrel had a hole of unspecified taper into which a single tool could be inserted. A rotating stop provided an accurate depth location for each rotation of the handle - with the tool being automatically ejected at the end of the stroke.

The simple Forming and Parting Single Slide that attached to the cross slide of the compound rest.

The long-travel tool slides of the George Adams 21/2" Precision. Note, on this example, the raiser block under the headstock to increase capacity and the spacer at the front of the cross slide to increase its travel.

GA 21/2 plain-turning lathe on the maker's very light treadle and flywheel stand

With the compound slide rest fitted


George Adams Home Page

GA Lathe Model 21/2  

G.A. Watchmakers' Lathes 

G.A. Round Bed Lathe

3.25" & 4.75" Screwcutting Lathes Models D, E, F, G & H

4" & 5.25" 4" & 5.25" Screwcutting Models A, B, L, KF1 and CL

3.25" & 4.75" Precision Lathes Models D, E, F, G & H

2.75" Screwcutting Lathe Model CS

Advertisements 1930

GA 21/2" Precision Plain Lathe

Watchmakers' Lathes

Portass-built Mk. 5 Lathe Photo Essay

George Adams of London
GA 21/2" Precision Plain Lathe
email: tony@lathes.co.uk
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