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JEN-SON Lathe

Although the background of the unusual "Jen-son" is unknown, it could, having its flat-topped bed machined with angled edges (and other design clues) have been English in origin. With its headstock pulley intended to take a round-rope "gut" drive the lathe looks to have manufactured circa 1900 to 1920 - though it may, just possibly, have been offered as late as the 1930s. Oddly, for a relatively simple and light lathe, it was fitted with a lever-action collet closer, the unit being carried on a bracket secured with bolts to the top of each spindle bearing housing. The bed, its chip tray, feet and the headstock were cast as one, with the latter somewhat cantilevered out from the end of the bed and carrying a 4-step pulley. Driven by a countershaft of simple construction -  a large central plain bearing with drive and driven pulleys overhung on opposite sides - the drive must have been intended to come from below, the makers fitting a wide jockey pulley at the front of the bed in order to stop the belt rubbing on the casting.
Drive to the carriage was by changewheels (through a lever-operated mechanism that appears to have operated a dog clutch), to a shaft that ran down the back of the bed. From there, at the tailstock end, it was transferred by a gear train to a leadscrew that ran down the bed's centre line, rather in the manner of an early Drummond.  Interestingly, the screwcutting chart was marked with columns that suggested changes of pitch could be obtained by altering the gearing at this right-hand end (and the provision of a short banjo arm at this point would seem to offer confirmation) even though it's something of a mystery as to how this bracket carried the gears. This convoluted system (though not the use of changewheels at the "wrong" end) was often used on early full-sized lathes when power-cross feed was required (and some smaller ones until the 1930s, for example, the Pools Major with a sliding worm wheel being mounted on the drive shaft and the other necessary gearing fitted to the back of the carriage).
Arranged conventionally with a leadscrew clasp-nuts in conjunction with a rack-and-pinion drive for hand operation, the carriage carried a handwheel of  distinctive design with finger cut-outs in the periphery and a cast-in radial bar that extended beyond the rim and carried a knurled handle. The compound slide rest used a short cross slide with a long (but not long enough) cast extension at the rear to protect the feed screw from swarf. Unusually for a small lathe of this era the cross-feed micrometer dial was large and clearly engraved. In order to provide a long enough travel the cross-slide ways were extended well forwards but, with the slide in any normal working position, the front of the screw was left exposed.
If any reader has a Jen-son lathe the writer would be interested to hear from you..

Jen-son lathe with the headstock casting cantilevered away from the end of the bed.

A jockey pulley, found fitted to more than one example of the Jen-Son, that allowed the belt from the base-mounted countershaft to pass over the front face of the headstock.

The carriage traverse handle (top right), like that fitted to the tailstock barrel, was of very distinctive design with finger cut-outs and a cast-in radial bar that extended beyond the rim and carried a knurled handle.

The leadscrew ran down the centre of the bed, n the style of an early Drummond flat bed (with the changewheel drive passing through a mechanism that appears to have operated a dog clutch) the drive being taken down the back of the bed by a drive shaft to a set of gears arranged, in a 1 : 1 train, across the tailstock end of the bed.

The compound slide rest used a short cross slide with a long (but not long enough) cast extension at the rear to protect the feed screw from swarf. In order to provide a long enough travel the cross-slide ways were extended well forwards but, with the slide in any normal working position, the front of the screw was left exposed. Unusually for a small lathe of this era the cross-feed micrometer dial was large and clearly engraved.

The simple base-mounted countershaft, had a large central bearing with the drive and driven pulleys overhung on opposite sides.

A foot pedal was provided to lift the countershaft and allow changes of speed.

The drive from handwheels to leadscrew was taken by a rear-mounted drive shaft to a set of gears arranged, in a 1 : 1 train, across the tailstock end of the bed - although it is possible that the gearing could have been adapted to other ratios by the use of a banjo arm or pick-off gears.

A slightly different Jen-son - possibly an earlier model. This too has the jockey wheel in front of the headstock

Lever-action collet closer

E-MAIL   Tony@lathes.co.uk
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JEN-SON Lathe