I think it's called a Balance Chuck.....It fits my 8mm lathe....why would I use it?....How do I use it?....Thanks for any input.

Tonyzee
I think it was used to hold a balance when polishing the pivots on the balance staff. I have seen similar types on e-bay, and thats what they claim, but I have never used one myself.

I don't get it....why not just remove the hairspring....the roller table....mount the balance in a chuck...and...polish-em up?

I have used them and they do work well, While you still must remove the hairspring, you don't have to go through the hastle of removing the roller table. Many of the thinner pocket watches and most wristwatches don't have hubs long enough to safely grip them in a regular chuck. Theoretically they also better center the object being turned and their design can provide more protection to the balance while it is turning.

Mike Miller

It is called a balloon chuck. In addition to what Mike said, I think that it also affords more protection to the balance wheel rim.

Ok...I think I get the idea....The balance goes inside this thing...a pivot peeks through that hole in the END CAP...and that's the pivot you polish...then ....the balance is removed...reversed....and the other pivot is polished....is this somewhat correct?....this thing is a.... PIVOT POLISHER?...

It is not specifically a pivot polisher, but a device to hold a complete balance wheel assembly and present a single pivot for lathe work of any kind. It could be polishing, minor pivot reduction or pivot straightening. Yes, you are able to work only one pivot at a time. These come in a few different sizes to better contain various size balances and staffs. Mine have a thin blued-steel face through which the pivot "peeks".

Mine also have the blued steel front-plates. I think that the one Tonyzee has pictured above has a screw-off front plate that can accept different ones to change the size of the pivot hole. A nice one if you have the extra plates. I know that I have seen these screw-plates at some marts.

Mike Miller

You are correct Mike...that is a screw-on/off front plate....sooo....I guess I'll be hunting more plates....in the mean time....I'm off on another adventure...Let's see...what do i have around that needs pivot work?....Thanks Guys...TZ