Hi...I'm working on a 16s 7 jewel Elgin PW....the balance staff has a slightly bent pivot....how does one straighten these pivots?...I usually just replace the staff...but...I just love a new challenge...thanks...Tony C
Posts: 148 | Location: Somerville, New Jersey USA | Registered: November 28, 2002
Alas... you probably don't. If it's bent more than just a little, it will break when you try to straighten it.
I don't do this but I've seen it done. The balance is put on a lathe and a special tweezers is used. The tweezers is about 1/2" thick... very wide. The tweezers is heated in an alcohol lamp and applied to the bent pivot while it is being spun at high speed. Very carefully, the tweezers is pulled forward.
Without heat, the pivot will break immediately. The heat has to be applied evenly... hence the wide tweezers.
Even with that technique and a lot of luck... you will break the pivot unless the bend is very slight.
Posts: 986 | Location: Flagstaff, Arizona USA | Registered: June 19, 2005
Well...here's what I've done so far...I took a small lenght of brass rod....(.71mm dia. fit the contour of the pivot best)....I polished it up and bent it like a small cotter pin...I soldered the closed end so it won't spread...I locket it in a pair of jewelers plieres...put the balance in a lathe...heated my "tool" in an alcohol lamp....looped the bent pivot with the "head" of my cotter pin...applied the heat of the cotter pin to the pivot...spun the lathe...and slowly moved the 'tool"...so the pivot rode down the Cotter Pin towards the soldered closed end..I followed this process about 4 times...IT WORKED....pivot looks pretty good..I polished-up the pivots...but ..now...how do I re-harden the pivot?
Posts: 148 | Location: Somerville, New Jersey USA | Registered: November 28, 2002
We don't do anything, once it's straight. I guess we figure that we've already been to the well, once too often!
Did you get that idea from me? If so, I'm glad my suggestion helped and I am most impressed at the way you improvised. If you ever see one of those wide tweezers, you'll know what it is and grab it!
Using heat is often necessary and it has to be done very carefully. The trick here is not to apply heat directly to the pivot.
Posts: 986 | Location: Flagstaff, Arizona USA | Registered: June 19, 2005
Thanks for the advice..I might have a pair of #8's...I'll look around....The balance jewels still look good...so...I'll put the balance back in and see what end and side clearnaces I have...I usually "spin" the balance with a shot of air....and check it in all positions...a good fit usually gets about a minute of spin before the balance comes to a complete stop.
Posts: 148 | Location: Somerville, New Jersey USA | Registered: November 28, 2002
Another good test is to see if the balance will "free-run;" I.E. run without the hairspring. You may have to get it started but if your train has good power, it should sustain the balance even without the hairspring. That's one way to eliminate problem areas. If it free-runs and still has problems, you are probably looking to the hairspring.
If the balance will not free-run and you have determined that there is good power to the train, then you can concentrate on the balance-pivots and the jewels.
Posts: 986 | Location: Flagstaff, Arizona USA | Registered: June 19, 2005