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Potts Milling Spindles, Milling Column
and Tailstock Capstan Unit

Potts Page 2

During the 1940s and 1950s, the G.P. Potts Company, based in Troutbeck, Windermere, was best known for three versions of their beautifully made, column-type high-speed milling and grinding unit. The company also manufactured a range of independent high-speed milling heads intended to be mounted on the top slide of small lathes to assist with more complex milling operations, gear-cutting and ornamental turning. They also produced a six-station capstan head, fitted with a Morse taper arbor and used in a lathe's tailstock.
With their spindles running in hardened bearings, two of the three column attachments were designed to mount on a hinged bracket (that allowed them to be used for milling and toolpost grinding) while the third was as built as an integral part of a milling slide. The latter type consisted of a 1.75" diameter column some 6.5" long (intended to be secured to a lathe's cross slide) with the spindle assembly able to be moved up and down through a range of 3.75" and also swivelled. A feed-screw of Acme form was fitted, complete with a finely-engraved bevelled-faced zeroing micrometer dial - and the rotating part of the head marked with similarly-clear degree graduations. The milling column might also, originally, have been intended to carry a simple dividing attachment fitted with changewheels taken from the owner's lathe, or as a proper dividing attachment with an overarm and a selection of division plates. If the latter was made, it is very rare, with only one example being found in recent times. It was also possible to mount a high-speed milling spindle, powered from on "overhead" (often a complicated and expensive drive system arranged above the lathe) but today more easily driven from a small motor carried on a bracket attached to the head.
In addition to the genuine Potts spindle, a good number of beautifully built home-made versions have also been found - probably made from commercial kits, or when the toolroom was either less busy or, surreptitiously, on the night shift .
Shown towards the bottom of the page are two long-popular, sought-after independent high-speed heads for use on a lathe's top slide. Available with the pulley positioned between the bearings (as the Mk. 1) or overhung (Mk. 2), each was supplied with three 8 mm draw-in collets and a plastic-handled drawbar. Potts also offered a well-made 7" x 4.5" saw table designed to mount on the bed of almost any small lathe (at 3 : 10s : 0d finished or 16 shillings for the castings in 1949) and also a special version of the milling spindle designed to clamp around the post that was cast as an integral part of the top slide on the Myford/Drumming M-Type lathe - a fitting normally used to mount the
Norman Patent height-adjustable toolpost..

Versatility. Potts spindle set up on a lathe to machine job held in a wood-collet chuck.

The high-speed collet-holding spindle is held on a rotating boss

The heads can be moved up and down the column or clamped to it with a pinch bolt

A drive pulley should be fastened to the end of the keyed shaft

Finely engraved zeroing micrometer dial

Degree graduations on the swivel boss

Acme-form feed screw with a neat, zeroing micrometer dial

Possibly a early Potts fitted with a bracket and arm to engage with a simple dividing mechanism that would have accepted changewheels from the owner's lathe.

Potts type vertical column fitted with a proper dividing attachment

What must be a "home-made" assembly complete with a high-speed milling/grinding
head with a jockey-pulley arrangement to guide the drive belt

Another well-made but non-Potts unit with both an indexing wheel and division plate

Potts Mk. 1  high-speed milling and grinding spindle with drive pulley between the bearings

Potts Mk. 2  high-speed milling and grinding spindle with overhung drive pulley

Potts Mk. 1 high-speed milling spindle mounted using the toolpost clamp on the top slide of a Myford ML10 lathe

Potts Mk. 2 high-speed spindle unit mounted on the cross slide of a Myford ML10 lathe

Potts 6-station tailstock-mounted capstan unit

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Potts Milling Spindles,
Milling Column and Tailstock Capstan Unit