email: tony@lathes.co.uk
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Portass Model C Lathe
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Advertised by the factory as a "Short Term Offer" - and available only direct from the makers - the "Model C" had a centre height of 3-inches and could be had with between-centres capacities of either 10 or 17 inches at prices (in 1953) of 13 : 17s : 6d and 15 : 10s : 0d respectively. Supplied without backgear or screwcutting the unusually deep box-section bed probably used saddle ways of the same dimensions as the "S" and was also fitted with the T-slotted saddle and single, swivelling tool-slide from early versions of that model. Unusually, instead of a traditional Portass full-nut and leadscrew to drive the carriage, on the "C" this was propelled along the bed by rack-and-pinion gearing with the handwheel carried on a proper apron and with reduction gearing to help provide a smooth, even drive. Both headstock and tailstock centres were the usual (inadequate) No. 1 Morse. The tailstock could, within limitations, be set over to turn tapers, though as this was arranged by adjusting the fit of the rear-mounted clamp and turning two screws set into the casting at the front (that, astonishingly, bore directly against the bed with no intermediate gib strip), the method was neither quick nor accurate. The other problem was realigning the tailstock once its initial position had been disturbed - it was in fact, according to an owner, very unwise to disturb it at all. As another cost-saving measure the tailstock spindle, instead of carrying a large thread, was driven by 1/4-inch Whitworth screw that also acted to poke out the centre when the limit of its travel was reached. The makers listed the headstock as being "reversible (meaning it could be turned round on the bed and then used for the outboard turning of wooden bowls) and offered a choice of either flat or V-belt drive. A further option was the use, on the spindle, of a large pulley (with a matching small pulley for the countershaft) to allow slower speeds. Two different headstocks have been found on this model the one at the top of the page presumably being superseded by that shown below with its deeper front face to gave better support to the bearings.
If any reader has a Model C, the writer would be interested to hear from you.