Advice on turning down thin pivots

[margolisd]

Hi guys. Any thoughts on best approach to turning down a thin pivot (.14mm) on the lathe after replacing? Thinnest pivot wire I have is .33. I’ve plugged it fine but keep braking it when trying to turn it down with the graver when it gets close. It is tempered blue steel and I’ve not softened it. Should I stick at it or change approach?

I’ve read that maybe I should abandon the graver entirely and use a sapphire stone? But they’re super expensive so wanted to ask if anyone had any advice. Perhaps on a good brand of sapphire stone that’s not over priced Burgeon.

The pivot is also quite long (long story, it is an adapted ETA part that has to connect with a power indicator module). Are there lathe accessorIes that support long pivots whilst they’re being worked on? Or should I just put the graver rest underneath it and stone it?

[JGrainger]

It should be possible to turn pivot steel but pressing it in may add a bit of hardness to the end. If I was struggling with this then I'd try rotating the graver to an angle so the cutting edge is at 45 degrees, with the tip above the work and the other end below the work. doing this will create a bit of an uneven surface on the work but should allow the material to be reduced in diameter so that the abrasive / burnishing tools have less to do.. starting from the least supported end. Ideally you'll need some sort of optical aid for this and something to be able to hold up to it as a reference diameter while working. A jacot drum is ideal for resting the pivot on for the latter stages of finishing but any stable and located (so it can't be knocked and run into the work) support or the toolrest might work if the height is spot on.

[nickelsilver]

Are you using steel or carbide gravers? Either will work, but both need to be sharpened perfectly. It should be no problem to turn to 0.08mm or smaller. I leave about 0.01mm and finish in the Jacot.

Check your gravers and keep practicing. How long is "quite long"?