It doesn’t answer the question of ‘how to make’ … but I think you will have better luck searching for worm and worm-wheel … because ‘loose’ as it may be, that’s what you have.

MichaelG.

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Edit: __ it hasn’t evolved very far from Leonardo’s design

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Ref. __ https://link.springer.com/content/pdf/10.1007/978-1-4020-5599-7_2.pdf

Edited By Michael Gilligan on 18/11/2022 17:25:58

Curiously OD of the worm has a double taper – but in the wrong direction if you were hoping to maximise worm/wheel contact. So maybe they were trying to minimise the w/w contact so that pitch mismatch wouldn't stop the job ?

A very interesting machine, Andy … do please keep us advised of your progress !

MichaelG.

Probably easier to make on a treadle lathe with a very slow speed. Wrap a piece of string around it to mark the spiral, mark with paint that will go into the gaps in the turns of string. Follow the path with a file hand forming a rough groove. As you get some definition for the groove the file will follow it under power. Just a version of hand chasing a thread.

No Dick you aren't daft, this is bugging me as well! It doesn't appear to work like a clock escapement but the rotation of the 3 armed fly would control the overall speed. But if you have to rotate this manually – what's the point? It would be easier to have a peasant with a crank handle attached to the ox or whatever?

And don't forget the nay sayers that state a worm cannot be driven by a wheel.

Regards Ian.

I've seen one of these working but sorry I can't remember where. 

Edited By roy entwistle on 19/11/2022 11:26:58

But the nay-sayers don’t understand, and therefore generalise too much.

MichaelG.

And rear wheel drive Peugeot cars up until they went FWD, don't know how many start worms though.

https://youtu.be/vwF6z2tJHVA shows a similar setup in operation

There are down-loadable copies of Joseph Moxon's "Mechanics Excercises" contemporary book with detailed instructions for making these machines.

dave8