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ManSon "DuoLathe"

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ManSon DuoLathe circa 1948

Second of the Small Machines' product range was the "DuoLathe", a model resplendent in a highly-polished aluminium and designed to appeal to those who needed a small but accurate lathe capable of mounting a screw-feed tool slide as well as a more traditional "tip-over" hand-tool rest. At 101/2" long, 33/4" deep and 71/4" high the DouLathe was slightly larger than the original ManSon and a more fully-developed machine - with many changes obviously made in the light of customer feedback and practical experience. The increase in size allowed the swing to be increased by 1" to 3", the between-centres capacity lengthened by 11/4" to 4 1/4" and the weight to rise by 2 lbs. The cross slide was increased in width from the 0.75" of the original to 1.0", its thickness from 0.31" to 0.45" and an extra thick T-slotted tool-holding section was cast in to get the cutting tool up to the right height. While the width of the lathe's base remained unchanged at 3.7", the headstock section was thickened from 1.75" to 2" and the spindle, now hardened and ground, enlarged to accept standard WW type collets and chucks, given a 5/16" bore and ran on ball races. Unfortunately the spindle was little more than a thin tube, and the bearings non adjustable. Because of its inherent flexibility, once installed the assembly could "wring" together, and be difficult to get apart - one solution being to run liquid nitrogen though the spindle to shrink it sufficiently to loosen the bearings. However, the ability to take WW (Webster Whitcomb) 8 mm collets (or "chucks" as they were originally called in the watch trade) made the lathe a much more attractive proposition to those
owners who already had a collection of expensive collets with their other watch-repair equipment. Incredibly, a slow-speed backgear system was also provided that used bronze gears, the sliding element of which was locked in place by a sliding spring clip. Combined with the foot-controlled, variable-speed (rheostat) motor (by Bel-Air products of California) this gave speeds from 100 to 3000 rpm. For electrical reverse, a switch was mounted on the back face of the bed. Instead of being held by a screw as formerly, the end cover snapped onto two split-spring dowels.
Also modified, the tailstock was given a slightly longer casting and barrel and the use of a conventional bed-clamping arrangement with an eccentric cross shaft and rear-mounted lever. It was supplied, as standard, with a simple "push" barrel capable of taking 6 mm WW jeweller's collets, chucks and attachments - although an optional self-eject, screw-feed barrel unit (illustrated below) was available as no-cost alternative. The body of the tailstock could, as on many larger lathes, be set over for taper turning and, offered as a further option, was an unusual accessory that the makers called a "micrometer-adjustable tailstock"; an examination of the illustration below should make its method of operation clear. One small but useful modification (also seen on some of the very late standard  models) was a machined surface at the tailstock end of the bed to mount a detachable leadscrew support bracket - its fitting allowing the saddle to be slid off the end of the bed without the need for further dismantling. The result of these modifications was to make the lathe the most desirable of all ManSon products, experienced users rating the DuoLathe as the best all-round model with a useful speed range and the ability to take a good cut on aluminium - and do real work.
Little was supplied with a new machines, just a motor with foot-operated rheostat controller, two centres and a headstock-spindle drive plate - however, shortly after the lathe's introduction, a "tip-over" tool rest became part of the standard equipment.
Optional-extras included the two special "micrometer" collet-holding and screw-operated tailstocks, a self-centring 3-jaw chuck, an independent 4-jaw chuck (both chucks had hardened jaws), a tailstock drill chuck and centre drill, drill V-pad, a  small standard tap and die set by Morris with four taps and four dies (sizes 00-90, 0-80, 1-72, 2-56), one tap and die holder, four bushings and one set-screw wrench. Astonishingly, in 2003 the Morris Company was still in business and selling the same set. Also available were various types of tool bits, lathe dogs, spare belts and wrenches. Later, concurrent with the externally very similar "Master" range of lathes, further accessories were added including a rather fine leatherette-covered carry case with reinforced corners that could hold the lathe and a number of extras - this case must be the hardest-to-find of all the types offered. 
Shortly after the announcement of the DuoLathe, a third machine joined the line-up, the very rare, less expensive "MonoLathe" - a version of the DuoLathe intended just for simple plain-turning work with the bed (but not the stand) painted black. The MonoLathe, while retaining the backgear and a ball-bearing supported collet-holding headstock spindle, lacked a carriage assembly and leadscrew - the maker equipping it with just a tip-over toolrest. Lacking a bed rack - the normal place for the serial number to be stamped - on the MonoLathe this was punched (prefixed by J9) into the left-hand face of the main body, to the lower right-hand side - and so is not visible when the end cover is in place. Electrical control was by a rheostat foot unit, not unlike that used on a sewing machine, with a reversing switch on the back face of the bed. Few examples of the MonoLathe can have been made, the highest serial number so far encountered being 110; indeed, so slow must sales have been that a number were converted by the manufacturer to DuoLathe specification - which could be the explanation for why, very occasionally, an example of that model is found with the black bed - the rarest and so most collectable ManSon of all.
Probably so that it could concentrate its efforts more lucratively elsewhere as the post-WW2 economy for Californian machine shops began to revive, on August 4, 1949
Small Machines Incorporated was sold/spun off as going business to MasterSon Engineering Co. of 1416 Westwood Boulevard, Los Angeles. In 1953/54 (just three years before their demise) they introduced a line of three new lathes that used the model description "Master".
Master Model S
, for "Standard", had bronze bearings,
Master Model BS for "Ball Bearing Standard",
Master Model BWW for the "Ball Bearing Large Spindle", for 8 mm WW type collets. This latter machine could be specified with change gears for screwcutting, a thread-dial indicator, built-on countershaft unit and various factory-installed accessories - a remarkable achievement in a lathe just 10 inches long.
The last known dated information originating from the Company was marked by the printers '
1957' , three years after the introduction of a small lathe was to dominate its market sector for many years - the Emco "Unimat"
Should any reader have a MonoLathe, or a DuoLathe with the black bed, the writer would be interested to hear from you

Duo lathe Photo Essay..

A DuoLathe fitted with a (rather overhung) ring-scroll three-jaw chuck, from a Sherline lathe. The chuck is carried on the end of a Starrett WW-type collet.

A crowed assembly: speed-reducing countershaft and backgear neatly enclosed

Centre: the backgear assembly was located by a sliding spring clip

Another view of the spring clip that retained the bronze backgears in place

DuoLathe showing the two-stage drive from the fan-cooled, variable-speed motor to the headstock . The backgear mechanism for slow speeds can be seen clustered around the end of the headstock spindle and this model also has a graduated collar on the cross-feed screw. The end cover was not screwed on but pushed over two split-spring dowels

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ManSon "DuoLathe"
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