I doubt that would work as you would end up with little thread as you are trying to cut a shallower thread into only the crests of the 1.5. Easy enough to make one or find a local job shot that can.

And the old motorcycle is? I have a puller for an old motorcycle, too, but not the motorcycle. It is a metric thread, for sure…

If I've understood how this works correctly, could you buy one suitably undersized, loctite a nut on then cut the required thread onto the nut. There seem to be some around for less than £10 at m24/m28

Edit: just realised that's essentially what Bill suggested above

Edited By Tris on 14/01/2023 19:09:56

Having a lathe, this is the way to do it. If you are new to thread cutting, it will take some time to learn but it is time very well spent.

As a last resort, find some one near that will cut the thread for you, watch how (s)he does it and learn something new.

Edited By Huub on 14/01/2023 21:40:53

That might be your best solution right there. Personally though, I would make one complete out of mild steel. Usually good enough for occasional hobby use. You don't need a mill to put the spanner flats on it. Either file them on good enough for a spanner to grip, or just hold the flywheel to stop it turning. Or hold the puller with vice grips etc.

As you probably already know, with a mild steel puller especially, don't just keep screwing the central bolt in until one of the two threads strip (usually the large one for some reason). Tighten it up as tight as you dare without risk of stripping anything, then give the head of the bolt a good sharp rap with a 2LB hammer. The shock will usually break the taper loose where steady force will not. And lubricating the bolt thread is a big help too.

There are a lot of thread cutting video's on YouTube. This will get you started.

This thread has only a small (1 mm) pitch. To keep it "simple", you can cut this thread at a 0° infeed angle (top slide angle). To avoid overloading the lathe, you can do the cuts using cutting depths of 0.05 mm.

For a self ground sharp tool (60° tip), you need a total cutting depth of 0.65 mm.

If you find the thread to loose, you can make a new one and cut it a bit (0.05 mm) shallower.

Success

I'd hold it in a 4 jaw chuck (or a collet if you have one) then if you make it too big, you can set it up again and take another cut. A sheet of white paper on the bed with a bright light shining on it helps, just engage half nut, wind the saddle back with the handwheel to take up backlash and fiddle with cross slide and top slide till you can't see the light

Edited By duncan webster on 15/01/2023 15:26:57

Don't be afraid to remove the threaded part to offer up to the flywheel. To cut deeper, all you have to do is back off the threading tool, bring it into position halfway along the thread and shut the leadscrew nuts. Turn the chuck by hand to remove the backlash, and bring the tip close to the job. Use the compound to get the cutter aligned with the groove of the thread, using a piece of white paper and a torch to see better. Even a 1mm pitch can be matched closely, and it is just an extractor, not an aircraft part.

It would be best to practice on something soft like aluminium or plastic. Even a small thread like1mm pitch will need to be cut in at least 3 passes. The thread total depth will be 0.5mm from initial contact, and I would go 0.2, 0.15, 0.1 and 0.05 depths getting less as the tool has to cut more each pass. An aluminium thread of 8mm or longer engagement in the flywheel would be more than strong enough to make an extractor without resorting to using steel. And a 12mm thread with a decent bolt in it would finish the extractor, it won't be used very often.

Another thing, if you make the extractor body double ended, if the first end is too tight, remember the depth of the last cut and do the other end deeper by about 0.1mm.

Edited By old mart on 15/01/2023 19:07:31

To test the thread for fit in the flywheel, take the whole chuck off the lathe with job intact and try screwing it into the flywheel. Then if the thread needs more cutting, just put the chuck back on the lathe where it came off. Assuming of course you have a small hobby sized lathe and not something with a 12" diameter chuck etc!

And you can buy a 30 x 1mm die on Aliexpress for about 10 Quid and use that to final finish the thread. Just takes a few weeks to get to you from China.

Edited By Hopper on 16/01/2023 09:33:03

Thank you for following up with a ‘conclusion’ to round out the thread – good luck with the rest of your rebuilding..