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First produced in the early 1920s this delightful machine was Benson's smallest lathe, with a centre height of 2 1/2" and a capacity between centres of 1". It was available in either plain-turning or screwcutting versions, the maker's code name for latter specification being "Benly" - but unknown for the former.
The headstock spindle and front bearing were both in hardened and ground cast steel and formed into a double cone whilst the left-hand end bearing was a split-cone, phosphor bronze bush, adjustable for wear. The headstock spindle nose was hardened and ground and threaded for chucks and backplates; a draw-in collet tube was fitted as standard and supplied with a combined collet and centre; collets were available in 1/64" increments to a maximum capacity of 3/8". The spindle, fitted with a 4-step pulley (with diameters of: 43/8", 37/8", 33/8" and 27/8" diameter) was designed to accept 5/16" round leather belt whilst the drive countershaft, with its swivelling bearings and fast and loose pulleys, could be mounted on the bench, wall or ceiling.
In order to obtain a slow carriage feed (and cut the fine threads suitable for instrument work) a 20 t.p.i. acme-form leadscrew was fitted. However, it is not evident from the illustration quite how the screwcutting was arranged for, not only was there no tumble reverse, there appears to have been no dog clutch on the leadscrew and, with the saddle nut of the "full" type, it is not clear how the drive could be disengaged.
The cross slide with its travel of 31/4", was propelled by a square-section thread running through a bronze bush with both top and cross slides fitted with, for the time, with decently-sized micrometer dials engraved at intervals of 0.001".
The tailstock was guided by a central V-way, just as on the company's larger lathes, but was unfortunately, fitted with a tiny No. 0 Morse taper, a fitting that would have caused the operator endless frustration.
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