by MrRoundel » Tue Sep 05, 2017 10:50 am
Thanks for your input on this job, Bob. Years later, I finally ended up getting a new staff from larry Crutzinger (Hamiltonparts.com), and am tackling the restaffing job. I have just successfully removed the hairspring, but not until I fought with it for a couple of days. Below is a post that I added to my similar thread on the NAWCC message board. Maybe someone will find it handy. Or perhaps Bob will respond with a warning not to do it this way? Either way, the post describes how I went about it.
Cheers all.
OK, so after finally working up the courage to earnestly try to replace the staff on my Hamilton chronometer, I bought a staff from Larry Crutzinger. For hairspring removal, Larry suggested that I might try to lever the collet up while spreading it at the same time. I couldn't figure out a way to get under the collet without having too much of a chance to distort the helical hairspring or scratch the balance arm. Then I re-tried something that might be unorthodox, dangerous, or one of those secrets held by the "chronometer-guild".
I had been supporting the balance wheel on a movement-holder made especially for a Waltham '92 model (Not the side with nubs.). It supported the rim, and 60% of the arm, very well. Still, I could not get the collet to do anything but spin...no lift. I tried many times, with many differently shaped wedge-tools.
As my next "trick", I decided to try again by letting physics(?) work more in my favor, that I would turn the balance over and push from the bottom rather than attempt to lift from the top. I was able to get a well-formed-for-the-job screwdriver tip into the outside of the collet. It got a good enough bite that I decided to twist it while I had another brass wedge brought in from the other side and twisted it to lift while I pushed a bit with the top screwdriver. Voila, the balance dropped cleanly and everything appears to be quite undamaged.
I used a wooden 16s movement holder to support the balance during this attempt. It worked fine, but didn't support the arm of the balance, just the rim. Fortunately, it didn't take a lot of downward force to get the collet to finally drop.
Again, while this may not be the suggested method, and carried its own risks, I wish I would have tried it sooner, as there may be a scratch or two on the collet that will be seen under magnification. Nothing terrible, but slipping out of the slot is a reality, especially if you don't have the right tool with the right angle. And seriously, I doubt many have that tool without making one by finding the right angle by trial and error. And you always have to be pushing down, thereby fighting yourself, when you spread the collet from the top.
Your mileage/damage may vary. Cheers.