What is it?

[JHargrove77]

Hey everyone,
Picked this up with a group of 8mm lathe collets off e-bay. I have no idea what it is, or how to use it. Can someone educate this newbie?

[DRichards]

Hi JHargrove77,
That would be a Balance Chuck also referred to as a Balloon Chuck. It's a very useful tool. It's used for polishing and working with balance staff pivots while leaving the complete balance assembled. The balance wheel with hairspring and roller attached can be inserted inside the barrel of the chuck with the pivot needing work sticking out through the hole in the large disk. In many cases the disks are removable and interchangeable with other disks with different sized holes for accommodating a range of pivot sizes. If you put 'watchmakers balloon chuck or balance chuck' into you tube search some helpful video demos on setting up and using the tool will come up.
Hope this helps.
Best, Dean

[JHargrove77]

Thanks Dean,
After your response, I looked a little closer. I had to hold it up to the light to see the tiny hole in the disk, but it's there. I'll try to find some instructions on it's use on the web. Thanks so much.

jim