But doesn’t it mate with the worm? You might need to make a worm to match the one on the layshaft and then make it into a hob……..

The only image that I could see of what I think are the Mk2s is the second from last and it looks like a straight cut gear and could be why the description has worm & wheel in inverted commas. Other models is is definately cut on the angle to suit the worm so it may just be the camera angle on the Mk2 making it look straight.

Im with you there Michael just as they do worm and wheel sets for rotary tables etc.

If it is only for feed and not screw cutting, so exact ratio is not critical, Aliexpress has a huge number of worm and wormwheel combinations for sale in all kinds of sizes from model car to industrial scale. Might be something there where a pair of metric  worm and wheel could be substituted. If you can work out the original DP, then you can find the nearest metric Module that would possibly substitute.

Otherwise, you could cut your own skew gear to match the existing worm. Skew gear has straight teeth , but cut at an angle to match the helix of the worm. If you go down that road, it might be worth reading Ivan Law’s book on Gears and Gearcutting (WPS) and both of GH Thomas’s books that have a bit about cutting skew gears to match worms. It works well for things like dividing heads because it only has point or maybe line contact between worm and wheel. Proper wormwheel gives full face contact so is better for power drive such as your application.

In which case you would have to hob a proper wormwheel, which is another whole can o’worms.

Thanks for posting the photo, Andy

… it’s a bit hard to tell which surfaces were machined, and which were formed by the worm, but it certainly needs replacing !!

MichaelG.

Note that if you change one gear from say 24DP to 1Mod, you have to change the matching gear or worm as well. A DP gear will not mesh with a MOD gear or worm, they are not that close. If going metric, you would need to buy the pair, both worm and wheel.