Hamilton 992 question

351 Views 7 Replies 3 Participants Last post by  Time in the pocket
I'm new to assembling a railroad pocket watch. My first venture is the Hamilton 992. I bought the movement, face plate, hands, and case on ebay then assembled them. The watch is running very well except for one issue. Normally the watch is keeping 1-3 seconds of day accuracy typically losing that each day. I time the watch with the website. About every 10ish days or so the watch will lose or gain 8-10 seconds a day. But after that it then continues with the 1-3 seconds a day lose.

Any ideas on whats going on? My guess is the movement needs to be cleaned and properly lubed? Or maybe there is a worn part? IDK.
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To be honest, i would be thrilled to death if some of my vintage watch and/or pocket watch movements got within 10 secs a day. There are a couple of members ( @Time Exposure and @Time in the pocket ) here who seem to be quite knowledgeable about vintage Hamilton movements so hopefully one of them will chime in.
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Does this change in time have anything to do with the amount of tension on the mainspring?
Everything in the watch has made at least one complete movement in 24 hours so in ten days it would have done this at least 10 times. So I would not suspect any gears or jewels as having a problem. Maybe narrow it down to a specific position when this occurs.
If it was every 24 hours then you could narrow it down but every ten days I cannot not say.

You can always clean and oil the movement it never hurts. Maybe change the mainspring.

I was on vacation so sorry about the late reply.
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Thank you Time in the pocket,

Here is my timing records from 4/29 to 5/18:
4/29 and 5/9 are baseline measurements. Then each day after that I track how much the watch looses or gains. The issues I see are on 5/03 and 5/14. Not sure what to make of it. I'm not yet ready to venture into cleaning and oiling nor changing the main spring. Is this variability normal for a watch like this being this old?

4/29/2023 at 10:00 am: 20s ahead
4/30/2023 at 04:32 am: lost 3 seconds
5/01/2023 at 06:21 am: lost 3 seconds
5/02/2023 at 06:20 am: lost 3 seconds
5/03/2023 at 06:51 am: lost 6 seconds
5/04/2023 at 11:53 am: lost 2 seconds
5/07/2023 at 08:00 am: gained 3 seconds
5/08/2023 adjusted rate faster.
5/09/2023 at 09:00 am: 1s ahead
5/11/2023 at 07:25 am: lost 1 second
5/13/2023 at 07:25 am: lost 3 seconds
5/14/2023 at 08:40 am: lost 8 seconds
5/16/2023 at 08:40 am: lost 11 seconds over 2 days. lost 5.5 seconds per day
5/18/2023 at 08:50 am: lost 1 second over 2 days. lost 0.5 seconds per day
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Positioning errors ? If so i think those changes would be quite acceptable.
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Yes I would be in agreement with mikeyt_53. It does look like positioning errors. You will never get an old watch keep exact time in all the different positions. Just too many variables.
I also agree that the amount of variations is acceptable in an old watch. Even the 992 Hamilton which is a good watch.
Do you have a watch timer that will tell you instantly how much the watch is gaining or losing in a 24 hour period.
That can be extremely helpful when troubleshooting problems. That way if you make an adjustment you know right away what effect it had on the watch and what the watch is doing in different positions.

If that was my watch and I do have about 5 Hamilton 992's I would be happy with that time keeping.
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Here is a question for someone: what is the lift angle of the Hamilton 992 movement. I can't find that anywhere.
There was a fellow over on the NAWCC forum who figured out the lift angle for quite a few American made pocket watches.
He has listed the Hamilton 992 with a lift angle of 48*.

I do not believe there is a published factory spec that is available.
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