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William Benson Ltd. was established in 1855 and became known for their high-quality lathes in the years prior to World War 2. The firm, based in the Robin Hood Works in Nottingham, England, was originally engaged in the manufacture of machines for use in the extensive and important Nottingham lace trade and only later branched out to include hand and power presses, swaging machines and a line of surface plates, straight edges and other inspection and precision measuring equipment. The firm also had the facility to design and manufacture special-purpose tools - their boast being that they could "design and make any high-grade single-purpose machines for any operation."
Benson "Precision Bench Lathes", as the company described their machines using the contemporary nomenclature, enjoyed a formidable reputation and were favoured by users engaged in critical work including, amongst many others, the Royal Air Force, numerous Admiralty Experimental Stations, The Government Gauge Factory, Sperry Gyroscopes, Cambridge Scientific Instruments Ltd., the Royal Aircraft Establishment at Farnborough and the Navy - there is one on H.M.S. Belfast moored in the Thames.
The lathe was built in early and late types and always fitted with taper turning (9-inch and 25-degree capacity) as standard; backgear, however, was listed as an option and, when fitted, allowed spindle speeds to span 70 to 840 rpm. The headstock carried a hardened and ground spindle whose nose threads ground were finished in situ after assembly to ensure absolute concentricity. The spindle bearings were of traditional "precision bench lathe" type - as first developed by Stark in the U.S.A. during the 1800s - in hardened and ground cast steel and formed as a double cone (shallow for support and steep to absorb thrust) at the front and a tapered bronze at the rear. Although the 3-step cone pulley was set with its largest diameter to the left the purpose of this arrangement - to allow a greater mass of supporting metal to surround the front bearing - was, unfortunately, not taken advantage of by the makers, the cut-out beneath the bearings being purely rectangular in shape and the casting the same width from end to end. It is believed that later lathes had this deficiency corrected by the addition of a large fillet in the casting arranged so as to give better support to the bearing housings.
As befitted a genuine precision lathe the bed of the Benle was enormously wide and deep in comparison to the centre height and carried an unusual combination of ways: flat-topped with narrow 90-degree sides for the saddle and a sunken V for the tailstock.
To preserve its accuracy the leadscrew (clasped by double nuts) was used only for screwcutting, the power sliding and surfacing feeds being provided by a separate powershaft with selection by a quadrant arm (located by a spring indent) and engagement by a flick-up-and-down lever on the front of the apron. On early models the power shaft could be driven from either the screwcutting changewheels or, at a much finer rate of feed, by an auxiliary belt drive. The power feeds on later machines were arranged differently: besides connecting to the screwcutting changewheels the gear on the end of the headstock spindle also drove a rear-mounted layshaft that took drive, via sprockets and chain, to a separate train of gear feeding into a 4-speed gearbox from which emerged the power shaft..
Power cross feed was not fitted and, because the drive to the power-shaft gearbox did not pass through the headstock-mounted tumble reverse, the apron had to be fitted with a feed reversing mechanism (using bronze bevel gears) with selection by a quadrant selector and engagement through a flick-up-and-down bronze "finger-hook" lever positioned in the bottom left-hand corner of the apron's front face. A long cover, extending from the left-hand face of the apron, gave protection to the 1-inch diameter precision leadscrew.
The compound slide rest had hand-fitted and scraped slides and was driven by square-section threads running through bronze nuts. The top slide was mounted on a large, very stable round boss and the micrometer dials, even on the models from the 1920s, were of an unusually generous size for the time.
Inexplicably, but as on so many precision bench lathes, the tailstock barrel carried an inadequate a No. 1 Morse taper.
Although in post WW2 years only the larger 33/4-inch centre-height (actually 313/16") backgeared and screwcutting "Benli" was built (together with a basic version) originally others sizes were offered: the "Benla", a 33/4-inch centre height plain-turning model (with detachable screwcutting as an option, when it became the "Benle" ) and the "Benly" a 21/2-inch x 22" screwcutting lathe. A useful range of beautifully-finished accessories was also listed.
Benson Serial Numbers allow some insight into production numbers - one marked 598/45 for example would almost certainly have been made in 1945 and have been the 497th example made - assuming numbers had started at 101, as they often did. Sadly, production of these fine lathes machines stopped during the mid 1940s - and they are now rare and sought after with experienced turners all agreeing that the quality of their construction is outstanding.
If any reader has a Benson, the writer would be pleased to hear from them.
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