Hello all from a total Newbie, here's my question...how does one go about holding the lower portion of a balance staff in order to polish the upper pivot? On my Elgin movements the lower portion is conical and a wire chuck won't hold it. A balloon chuck perhaps?

Thanks, Mike

collet in lathe

Collet in lathe.

Thanks for the replies guys, maybe I should have said that the lower portion (roller table side) of the staff is "tapered". My lathe collets won't hold tapered shafts.

there is so many surfaces to chuck it on the staff

Hi Peter you're definitely right but, used to hold a tapered shaft, the collet will only grip with it's outer edge(its "mouth")whichever surface you tighten it on. This leaves the rest of the shaft, inside the collet, to wobble about....something we don't want. So what's the solution, a balance chuck?

I always had good results with a simple collet. The Balloon Chuck is very finicky and while it is a great advantage where you have to work on an assembled balance wheel, it is far less desirable for a separate staff as a part alone. The tapered section of the balance staff is not unlike the end of the collet which actually grasps the staff body and also there is often a step or shoulder on the staff to serve as a chuck stop and also help hold the staff on center.

Hello David thanks for your input. This is exactly what I'm trying to do....polish the pivots on an assembled balance. Of course my #6 collet may not be in perfect condition either...wouldn't be the first time I got a bad collet on E(vil)Bay

Mike

Michael, if you have a balance wheel assembly a balloon chuck is the safest way to polish the pivot. Mounting the Balance wheel into the chuck requires the right size chuck ad some practical experience with dealing with little things like this. I Googled unsuccessfully for an instruction on the subject.

How about using pivot lathe - Jacot tool? You should be able to polish it without disassembling balance wheel assembly.

Topic moved into correct forum

Thanks to everyone for your advice, I don't have a Jacot tool Rafal but thanks for the suggestion. I'll probably go with David's solution of a balloon chuck (which I also don't have but which will certainly be cheaper than a Jacot tool).

Mike