Nooging round t'net it appears that Walker-Turner drills and drill heads have always been very fast running in the basic form. One brochure quotes 600 to 5,000 rpm for the 1940's – 50's four speed head using the standard 4 pole 1750 rpm (in USA) motor. Maybe around 510 to 4,100 for a straight swap to UK 1440 rpm motor. Even the 6 pole option doesn't make a vast difference in real world terms.
There was a low speed pulley option to give more metalwork friendly speeds. Basically the motor was inverted and a speed reduction belt drive arranged to an auxiliary drive shaft hung off the side of the drill. The multi-groove step pulley being moved to the top of the drive shaft to drive the drill spindle in the usual manner.
An old style spin drier spindle and housing would be a quick way of making an auxiliary shaft. Have used them for similar duties on a few occasions, re-purposing being easier than making a nice job of a ball bearing spindle, but the OEM mounting arrangements never seemed to suit the job. Terribly short sighted of the spin drier makers not to consider (my) repurposing needs! I usually resorted to a pair of U bolt style exhaust pipe clamps (Benelli Clamps?) after sawing off the original brackets. I imagine something like 3 or 4 to 1 reduction would be reasonable.
Coming up with a good solution to set basic belt tension with easy release to change speeds on the step pulley may require some creativity. All the ones I did were either fixed countershafts or two speed with slack belts and sprung loaded jockey pulley clutch so nowt to copy. Assuming a single fixed speed reduction drive an H shape mount with the motor one end, the auxiliary shaft at the other and a pivot in the middle would probably work pretty well. Needs a husky spring to generate belt tension. Trampoline or motorcycle centre stand spring perhaps with an over centre lever or cam to release tension for belt changes. Tension springs are inelegant but much easier to engineer in than compression ones.
Clive.
Edited By Clive Foster on 02/09/2017 22:43:48