Balance Staff Pivot Length

[mistergrumpy]

I have a Rone pocket watch balance with both pivots broken off the staff which currently measures 5.8mm. Looking at the jewels either side they're both recessed into the metalwork on both sides also which I'm going to have to look at but I'm trying to determine how much to add on for the pivot lengths. What figure would be realistic? 0.2mm each? It's quite easy for me to guess but with these very small measurements it's difficult for me to grasp it well enough, whereas with an inch or a cm it's easy.  

[szbalogh]

I would do the following. Take off one of the cap jewels. Put a thin wire through the hole jewel under it all the way down to the opposite cap jewel. Then bend the rest protruding from the hole jewel or mark the wire with a thin blade. Pull it out and measure from the end of the wire up t the mark/bending. Add a bit to this to make sure it will bi a tiny bit longer. It is better if it is longer, since one can file down from the length and then it will fit perfect. If it will be shorter, one can tilt the balance cock to set the correct endshake. 

[mistergrumpy]

Good call. Need to find some ultra thin wire though. I'd rather not be wedging the balance cock to suit the staff though. It's a bit too much of a bodge for me. (Nice home made lathe BTW. Been looking at your Youtube page)

[Marc]

What is the movement calibre?

If you know this then there are many references that give the critical balance staff dimensions, including overall length.

[mistergrumpy]

Couldn't find any markings on it other than Swiss made. I tried a single strand of electrical wire but that was too big but I got there in the end by removing jewels and some other bits as prompted by szbalogh so thanks. It's only a 7 jewel watch movement  but it looks nice and was bought as a gift to keep me busy.

[JohnR725]

Out of curiosity why do you need to know the length of the balance staff?

So as stated above there are reference books on balance staff dimensions including the length usually what I've seen is for American pocket watches although one of the books does have some other non-American pocket watches. So for instance the book American Watch Balance Staff Interchangeability. You can usually find this is a PDF available on eBay. but in the size range are looking for almost all are American. then usually when you're looking for balance staffs you need more than just the length you need the other dimensions.

So probably not of much use I am attaching a image of what the pivots should look like it's not really overly helpful for the length.

Then googling Rone pocket watch reveals quite a few so it would help if we had a picture to narrow it down. It looks like they probably didn't make their own movement so it's possibly somebody else's depending upon its age we might be able to figure out what it really is perhaps.

[Colditz]

I'm working on Cupillard 233 movement. It has a broken balance staff at the balance cock end. It also has broken staff jewel which I need to replace. I bought a balance wheel complete from cousins for the 233 but it is a tad too long. How can I make adjust to the length with out damaging the new staff? All advice is welcome.

 

[Nucejoe]

Dear mistergrumpy.

Show close up pix of the movement on this thread. if not identified, 

Poast " identify this movement" in appropriate forum.

Avoid long threads, hard to joiin in or survive the endless discussioons.

Balancestaff.com and Dr ranfft and other database provide some details.

Regards joe.