Hairspring amplitude problem…

[tmac1956]

All:

I recently muddled my way through solving a low amplitude hairspring problem on a Hamilton 10s. After cleaning and putting it back together I noticed that while it did run for a while, the amplitude was about half what it should have been. After investigating the usual suspects, I found that that the screws holding the regulator onto the cap jewel didn’t screw through tightly into the balance cock. After searching for some larger screws and finding them (it’s good to buy these tiny things in bulk – mine just paid for themselves), I had to ream out the cap jewel mount screw holes (that’s some tough steel by the way). Once I got it back together, the amplitude problem disappeared.

Apparently, the force that normally gets transferred from the hairspring, then into the timing regulator, then into the balance cock, and then into the watch plate was being dampened by imperceptible vibrations of the timing regulator causing the low amplitude. (BTW…this is not a high end regulator).

I just thought I’d share this should anyone else come up on the problem and cannot find the cause via normal means. Plus… I have so few successes these days.

Later,
Tom

[arutha]

Hi Tom,
well done on getting the watch done
One question though, if the screws were not allowing the regulator to be fixed securely would this also mean that the cap jewel would also have movement and maybe hinder the smooth running of the top pivot of the balance staff?
Paul.

[tmac1956]

Paul:
Arutha:

Yes. That’s a possibility as well. But since the regulator has a compression fit around the plate in which the cap jewel resides and the hairspring rides in the regulator hairspring slot, I just figured that the amplitude problem was related to that. When I took it apart initally, I didn’t notice the screw problem. However, when attempting to put it back together it was clear that the screws were sized for the cap jewel plate and were too small for the balance cock, because the cap jewel wouldn’t stay on the balance cock after I tightened it as tight as possible (I think a repairman must have used the wrong screws for this and it was just setting there waiting for something to put pressure on it and allow it to fly off). It seemed as though the hairspring was supporting the regulator instead of the converse, which explains why it was losing time before I got hold of it. Anyway, it works now. I hope I have the correct diagnosis. If not then why am I surprised? 😮

Thanks for the input. Give more if you can deduce something about the problem that I don’t see. It took me a long time to get it fixed so please let me know if I have an incorrect diagnosis of the problem. I am open to any ideas.

Thanks for the response!
Tom

[willofiam]

Hey Tom, I have read your post several times and have a couple of questions, (I have been a little slow lately)
@tmac1956 wrote:

After investigating the usual suspects

what were these for low amplitude?
@tmac1956 wrote:

I found that that the screws holding the regulator onto the cap jewel didn’t screw through tightly into the balance cock

Can you show a picture of that? Thanks a bunch, William

[tmac1956]

@willofiam wrote:

Hey Tom, I have read your post several times and have a couple of questions, (I have been a little slow lately)
@tmac1956 wrote:

After investigating the usual suspects

what were these for low amplitude?

A piece of tiny debris that might have gotten down in between the balance pivot and the jewel, or an unnoticed scored, dirty, or bent pivot – those kind of things.

@willofiam wrote:

@tmac1956 wrote:

I found that that the screws holding the regulator onto the cap jewel didn’t screw through tightly into the balance cock

Can you show a picture of that? Thanks a bunch, William

Sure… comming soon.

THanks!
Tom

[tmac1956]

Here’s the image. Note how the regulator is held in place by the cap jewel plate which is screwed onto the balance cock.

[willofiam]

Hey Tom thanks for the picture, I am not sure but should the regulator arm friction fit around the cap jewel housing? or is this a different style? only reason I am wondering is because I have not seen a setup like this. always wanting to learn something new, Thanks, William

[chris mabbott]

William you’re right, but on some models, usually Swiss, the top cap is compression fit onto the regulator arm via two screws that draw the plate in/down. Normally the screws are underneath to draw down, a pain in the posterior to hold everything together, but it looks like on Tom’s that the screws are on the top? A little odd.

Which brings me to my question Tom… Is the cap jewel rubbed in to the top plate or is it just sitting loose? Are you certain that the screws go on the top, maybe someone could have put it back incorrectly? Just curious.

Thanks..

[Bob Tascione]

Hey Tom,
I just took at a look at your thread and pic. Chris and William are right. You need to put the screws in from the underside and draw the piece down to the balance cock. The index should be friction tight around that piece. At least I think that’s the case.

Bob

[tmac1956]

Bob…

That’s astounding. I guess the person who put this thing together the last time, put it together with the screws backwards. Since, I’ve already reamed out the cap jewel plate to accept the bigger screws I guess I’m stuck with it now. This does make sense, as the screw never made contact with the bridge. Geeze… how often does one find a screwed up watch repair? I guess I just contributed to it as well.

Thanks – I’ve certainly learned something today.

Tom

[chris mabbott]

Watch repair, the final frontier, these are the voyages of….. you get the picture 😆

Thanks Bob, I wasn’t 100% whether American PWs used the under & up type or not, I think this is the first US model I’ve seen with the compression fit, although the more modern Americans (1950s) used Swiss parts. Those Swiss ones really bring out some creative language in me 🙄

Tom I’ve learned a few frustrating lesson from previous Botchmakers, as they say, and I’ve been guilty of committing them myself, who hasn’t DOH.
I now take nothing at face value as eBayers attempt to make their watches “run” by any means possible in order to sell.
But this is also good because, as I did for your watch, I searched for a 917 and saw the way the screws were mounted on an ebay model, so it’s a good research tool.

You can also use the pocket watch database to search your movement serial number, for American PWs, usually someone has a photo or drawing of the movement, you can get an idea of how it’s supposed to look.

I don’t think your watch is lost though, even though you’ve resized the holes, the original counter sinks should be underneath, you can open the sinks (or make new ones) to accept the larger head and re-tap, that would be an “acceptable fix” and be in line with the original. It would be like the old screws had broken off inside and you had to drill them out, no prob.
It’s a bit of work but very possible and I think it will be a good exercise and as you say, we learn, through pain 😆

Main thing, be young, have fun and drink mountain dew 😆

[randy]

Tom,..they are correct.
I wear one on my wrist daily..they are screwed in from the bottom.
Sorry I didn’t see this earlier..may have been able to help !

best

Randy

[tmac1956]

All:

I just found an exploded view drawing of a Hamilton in the Swigart Manual on page 108. It shows the screws going in from the bottom too. doh!

Taking detailed pictures of the watch during dissasembly doesn’t help much if it was “assembled” incorrectly – and – the watch repairer (me) doesn’t recognize the problem. It was obvious that the screws wouldn’t work going in from the top; however, I made the mistake of thinking that the previous person had used the wrong screws when assembling (having never had my hands on a Hamilton before didn’t help). This watch was bought at an estate sale a decade ago and was just sitting in a safe the whole time. The only thing I can think keeping the regulator from falling off was its attachment to the hairspring as thats what happened when I pushed the stud out of the balance cock.

Well… another one for the lessons learned file. Now that its working, I hate to try and re-thread those tiny holes… 😯

Thanks!
Tom

[willofiam]

Hey Tom, lesson learned, good thread even so. a rule of thumb can be if your starting to think of filing, re-tapping, bending, shimming or anything else that would alter the original = step back and ask yourself why (I have to ask myself 3 or 4 times because I dont hear very well), so besides all that and looking at the positive side you probably have helped alot of people out, thanks, William

[tmac1956]

William:

I am the perfect negative example! 😳

Thanks,
Tom

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