I have a elgin 12s Gr. 303,7j,on3p movement. I took it apart to clean and oil, and replace the balance staff. Upon re-assembly,the movement ran for a day or so with the proper oscillation of the balance wheel. Now I notice that the oscillation of the balance wheel is very short, as compared to what it was initially. The movement know runs sporadicaly,sometimes hours, and sometimes a day or two. Could the hairspring collet have worked itself loose and changed its position on the balance staff. Any advice appreciated,and will be acted upon.

Frank Juchniewicz

Hairspring collets can crack, and when they do, they can slip on the staff and result in the sort of problems you describe. If that turns out to be the problem, the best solution is to replace the hairspring collet, which is a fairly difficult task, but it's better than attempting to replace the hairspring, which would almost certainly result in a really wild rate that would be beyond the capacity of the regulator to adjust.

I'd say it's more likely, however, that the roller jewel in your watch has worked loose. That's a common problem, which is best remedied by removing the roller table, cleaning away the old shellac, and re-installing the roller jewel with fresh shellac. Don't listen to anyone who recommends "Super Glue" as a suitable substitute for jewel cement (shellac). None of the various cyanoacrylate (CA) glues such as "Super Glue," "Krazy Glue," etc., are very effective at adhering to the slick surfaces of jewels over long periods of time.

There could be other problems as well which would result in the sort of symptoms your watch is experiencing, but I'd rather see you start by checking the hairspring collet and the roller jewel before trying to offer any additional advice. Those are by far the most likely problems for the particular symptoms you describe.

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Steve Maddox
Past President, NAWCC Chapter #62
North Little Rock, Arkansas
IHC Charter Member 49

Steve, thanks for the advice,I will first check the roller jewel,for looseness,if found,will re-cement w/shellac to the roller table. If the jewel is tight, go on to the next step and check the collet, under the microscope for any cracks. Personally, I hope it is a problem with the roller jewel, life would be so much easier. Either way, I will let you know how I faired.
It will probably be in a couple of weeks,as I am going out of town next week, and won't be back for about a week.

Frank

Frank Juchniewicz

Steve, I checked the roller jewel for loosness,as you suggested,the jewel was tight. What I found was that the collet was slipping around on the staff. I closed the collet opening,some,and re-mounted it on the staff. I may have inadvertently expanded the initial opening in removing it from the staff in the first place. Do you think that the closing-down of the collet will last, or should I be looking to replace the collet. The balance wheel seems to be doing a little over 180 degrees now.

Frank

Frank Juchniewicz

Frank,

So long as the collet didn't crack (which they sometimes do), you're probably OK. It could be that the hairspring shoulder on the old balance staff was a bit oversized and expanded the collet, or it could be that the one on the new staff is a bit undersized, and the collet just didn't fit. In either event, as long as the collet is tight (and not sloppy enough to cause a poise errors or concentricity problems), that's really all that matters.

180 degrees of motion isn't what I'd call "glorious," but I suppose for a 7j model with an old spring, it isn't too bad. For fully jeweled watches with strong springs and fresh lubrication, balance amplitude should approach 270 degrees, or thereabouts. Anything over 300 or so is excessive, and will risk "knocking the banking," while anything short of about 220 (that's dial up or dial down) isn't too great.

Obviously, motion in the vertical positions will always be a few degrees less than that in the horizontals. A typical loss of about 20 degrees is to be expected, but if the loss exceeds 30 degrees or so, it's a good indication something's probably wrong (roller jewel striking the fork horn, bad balance jewels, etc.).

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SM

Steve

Thank you for the advice. And I will replace the mainspring,when I get a chance. Maybe I can get a"few more rpm's"out of the old girl. Could put her up in the two hundred degree range.

Frank

Frank Juchniewicz