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Some confusion surrounds the origins of Thum lathes. One source suggests that they were made from the beginning of the 20th century in the valley of Arve, in the département of Haute Savoie - though one example has been found with "Geneva" cast into the maker's nameplate. The latter lathe also carries a bronze bade stating "Henri Benediot Machines-Outils Bruxelles, showing that the lathe must have been produced in numbers sufficient to support an export trade.
As was so often the case in decades past, the maker's name was incorporated into an easily-changed door on the headstock-end plinth, so allowing manufacturers and dealers to disguise a machine's origins. "Made in England" the door might proclaim; well, the door might have been cast in England but the rest of the machine was certainly not made there. This trickery was not confined to machine tools - and those of a certain age might remember wallets that said, on a little tab, "Real leather". The tab was leather but the rest of the wallet was of the imitation kind
Of conventional design for its period and constructed to a good standard, the surviving backgeared and screwcutting Thum lathes appear to have had a centre height of around 6 inches (150 mm) and accept perhaps 40 inches (1000 mm) between centres. Drive to the leadscrew came from changewheels driven through a tumble-reverse assembly - this being of the common "German" pattern with the operating lever engaging in three horizontal slots. For the power sliding and surfacing feeds - selected by a quadrant lever on the face of the apron - a separate power shaft was provided. This took its drive from a sliding gear on the leadscrew - and so allowed it to be disengaged when not required.
A clue to the lathe's quality (a common thing to check) was the tailstock. This was secured to the bed by an eccentric cross shaft turned by a long, captive lever; the spindle, instead of being clamped by that horrid, quick-wearing method of a long slot closed up by a clamp was, instead, locked by a proper "split barrel" assembly.
In many respects, the lathe was absolutely typical of its time and very similar to those made by Ehrlich in Germany.
If you have a Thum lathe, the writer would love to have pictures of it.
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