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Benson Miniature
Milling Machine

Benson Miller Page 2   Benson Home Page

A Benson lathe catalogue is available   

Virtually unknown - pointing to the fact that few can have been made - the Benson milling machine would have been current during the 1930s, one example carrying a brass plate inscribed: Air Ministry Contract No 66794/37CX11 with the year of manufacture stated as 1938 and the serial number 843. Well made, in typical Benson fashion, the miller was a simple, horizontal type that lacked the provision to carry an overarm and drop bracket to support a full-length arbor - its use being confined to stub-mounted cutters. Unlike similar models from American makers of small precision machine tools, for example Ames, Cataract/Hardinge and Rivett,  it more resembled the Carter & Hakes in having a narrow, one-piece body and integral foot with an elevating knee and compound table assembly. 18" x 47/8" the table had two bevelled-edged T-slots and a single traverse T-slot off-set from the centre line - the latter possibly intended to mount the maker's dividing attachment. Both the longitudinal and traverse feed screws were  0.625" x 10 t.p.i., the lengthwise travel was 10.5",  the screw passing through a bronze nut split and adjustable to eliminate backlash. The 3.5" of cross travel was provided by a very large-diameter, finely threaded boss that meshed with a rack - in exactly the same manner as employed on some Pre-WW-2 Mikron precision milling machines. Elevation of the knee though its 6.5" of travel was through right-angle drive helical gears and a vertical screw, this giving a smoother, more controllable feed than the ordinary bevel-gears and screw (or the simple lever-lift type) sometimes found on this class of machine. High-quality, finely-engraved zeroing micrometer dials were fitted to each axis, their faces having a slight bevel and with locking by knurled-edge, face-thrust screws - the design ensuring that the setting was not lost as the lock was applied.
As the machine was limited to basic work with a stub cutter, the intention may have been to supply a machine that could be tooled as part of a production process or used along aside more complicated mode
ls for simple jobs. However, far from being a simple machine, it reflected the Benson Company's obsession with quality, having a spindle with a double-step taper at the front (shallow to take radial loads and steep to take axial thrust) and both a threaded nose and a ground taper to accept draw-tube retained collets. Bearings were a shallow angle, tapered white-metal type at the front and, at the rear, a parallel-bore in bronze with a tapered outside with a bronze retaining/adjusting nut screwed to its end face.  Inboard of the front bearing the spindle had what appears to have been a ground-in thread (8 t.p.i. x 1.625 o/d) that drew the spindle into its bearing housing to set the end thrust against the steep taper ground into the outside face of the bore.
If you have a Benson miller, the writer would be interested to hear from you,
With thanks to Mr. Neil Partington for taking the time and trouble to submit the photographs below of a refurbished machine..

Benson precision miniature milling machine - converted from flat-belt to V-belt drive

Table at its lowest point. Total vertical travel was 6.6 inches

Table at its highest point 

The original countershaft survives together with its over-centre, adjustable belt-tension locking mechanism.

Left and right-handed threaded countershaft belt-tension adjusting block

Bearings were a shallow taper white metal at the front and, at the rear, a parallel-bore in bronze with a tapered outside with bronze retaining/adjusting nut screwed on its end.  Inboard of the front bearing the spindle had what appears to have been a ground-in thread (8 t.p.i. x 1.625 o/d) that drew the spindle into its bearing housing to set the end thrust against the steep taper ground into the outside face of the bore.

Front spindle bearing

Spindle with retaining nuts, rear bronze bearing and its adjuster nut and the collet draw-tube

Front tapered bearing with a steep thrust face at the front - the 8 t.p.i. x 1.625 o/d thread appears to have been ground in

Bronze ring used to pull the rear spindle into its housing

Front bearing housing

Felt from the top-mounted oiler directed lubricant through a slot cut  in the bearings

Rear bearing and its bronze retaining nut  Pictures continued here

E-Mail Tony@lathes.co.uk 
Home    Machine Tool Archive    Machine Tools For Sale & Wanted
Machine Tool Manuals  Catalogues   Belts   Books  Accessories


Benson Miniature
Milling Machine

Benson Miller Page 2   Benson Home Page

A Benson lathe catalogue is available