I ran into something new yesterday. I have a Hamilton 974 that I was using every day and it was keeping really good time. Last week some time I decided that I wanted to tweak the regulator a little since it was gaining 2-5 seconds per day. I got the regulator set and proceeded to reset the seconds hand. I always stop the balance wheel with a small camel hair brush to do this. When I was done I put the watch back in my pocket. The next few days the darn thing started to gain 2 1/2 minutes per day. So I put it on the watchmaster to see what might be wrong. Sure enough the rate was + 2 1/2 minutes per 24 hours. I didn't have time to look into the matter at that time,so I put it in a drawer for another time. Last night I had some time to work on it and started looking things over. I figured that I might have gotten a piece of lint wound up in the balance when I had stopped the balance with my brush. I couldn't see anything at first,so I took a closer look at the balance jewels with a stronger loupe. I could see that there might be something in the lower balance jewel,so I decided to take out both the upper and lower jewels to re-clean them. What I found was a small piece of lint in between the cap jewel and the pivot hole jewel in the lower set.(???) So I cleaned both sets of jewels in my ultrasonic. Then I put them back into place,being extra careful not to get anything in them,then put the rest of the watch together. When I tested it again on the watchmaster there wasn't any change in the rate. That really had me going then. So I gave up and adjusted the mean time screws to compensate for the rate. The first try didn't net the results I was looking for ,so I gave the screws a few more 1/2 turns. That time it did slow it up to about +1minute per 24 hours. Hhhhmm,now what? While I as thinking this over I was looking at the demagnetizer sitting next to the watchmaster,and thought what the heck. So I ran it through the demagnetizer and tried it again on the watchmaster. This time it ran -3 minutes per 24 hours. From what I have read in the watchmaster manual when a watch shows magnetism the lines on the graph are usually wavy. I guess that isn't exactly true. Anyway I had to undo what I did to the meantime screws and now the watch runs fine. Now I'm wondering how the watch got magnetized in the first place?

Larry,
Magnetism is usually the easiest thing to correct but almost always the last thing we check (after taking everything apart, etc.). From my experience and what I`ve read it can cause a watch to run fast or slow which is a bit puzzling. Here is a link to a post I made some time ago regarding an experience I had. I imagine the watch has to be in proximity to a magnetic field to become magnetized in the first place.

Magnetism

Shot in the dark here....maybe the brush created a static discharge at the balance when you stopped the balance the last time. I've used camel hair brushes in work here at the Institute, and when the air is dry during winter, I usually give up using my brushes on equipment cleaning, as all they tend to do is move the dust around, as the static buildup tends to just attract the dust I'm trying to remove. Maybe you had just enough discharge to cause the hairspring to go screwy that round.

Just a thought....Regards. Mark

Larry,
Did you put the rest of the watch through the ultrasonic? I think that just putting a watch through one could cause it to be magnetized. I always demag after going through ultrasonic cleaning. Another possibility is that you had walked through a magnetic field when carrying the watch. The same thing that causes magnetism in a watch is the same thing that can fix it. The demagnetizer degouses(sp) the watch by hitting it with a magnetic field. Hit with a strong magnetic force again and it is magnetized. I have found this to be good advice,If a watch is running erratic or fast, the first thing to do is demagnetize. It is surprising how many poor running watches can be fixed by this simple action. A lot of times when watchmakers take in work they go to their watchmaster timing machines to do all the diagnostics which can create a lot of uneeded repairs.

Mark,
I often wondered whether a camel hair brush would create magnitism in a hairspring during the dry winter months. I use to use a camel hair brush while poiseing balances. Last winter I was haveing a hard time getting a balance to poise. Then I happened to notice that when I held the brush close to the balance wheel one side would be pulled towards the brush. Now I use a bellows to move the balance wheel on the poising tool.

Scott,
I had cleaned the movement some time before all this happened. So far I haven't noticed any magnitisim after I have cleaned and re-assembled a watch. But maybe ther is something to it. I should run all the watches through the de-magnitizer from now on,just to be on the safe side.

A friend of mine taught me to always turn off an U/S pot before removing the parts because removing them while the pot is "boiling" will tend to magnetise them.