American balance Timing/Meantime Screws vs Regular Balance Screws

JuliusSqueezer

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Mar 17, 2021
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I have a 15 jewel Illinois 12 size unadjusted movement that is running about a minute fast a day with the regulator arm positioned in the center of the cock.
I’m wanting to adjust the watch so it sits nice and pretty looking but I’m not sure if what I’m looking at are indeed timing/meantime screws because they are brass.
I have only ever seen steel meantime screws and these look similar, but their threads aren’t as long as the steel ones so I’d rather not do anything until I know for sure what I’ve got in front of me.

I’m hoping someone here can tell me if the balance in the picture below has timing/meantime screws or not:
1631725641761.jpeg
 

Skutt50

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Mar 14, 2008
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A timing screw normally can be screwed in or out to adjust time. Your screws seems to be screwed all the way in so you need to replace a pair of screws to make such adjustment. Timing washers is another way to slow down a balance. I would not recommend that at this point

You can hopefully adjust one minute with the adjustment screw. Give it a try and consider changing the screws only if you find the looks totally unacceptable.

It actually looks like the adjustment arm is closer to the F than the S so some adjustment should look fine.

Also important to consider is that you should have the watch serviced before any adjustment is made. E.g. low amplityde of the balance may cause bad timing. An unserviced movement that shows bad time may recover after a COA. (clean, oil adjust), and by then any change of timing screws has worsened the situation.
 

JuliusSqueezer

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Mar 17, 2021
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A timing screw normally can be screwed in or out to adjust time. Your screws seems to be screwed all the way in so you need to replace a pair of screws to make such adjustment. Timing washers is another way to slow down a balance. I would not recommend that at this point

You can hopefully adjust one minute with the adjustment screw. Give it a try and consider changing the screws only if you find the looks totally unacceptable.

It actually looks like the adjustment arm is closer to the F than the S so some adjustment should look fine.

Also important to consider is that you should have the watch serviced before any adjustment is made. E.g. low amplityde of the balance may cause bad timing. An unserviced movement that shows bad time may recover after a COA. (clean, oil adjust), and by then any change of timing screws has worsened the situation.
Right, no meantime screws.

Thank you.
The screws on the the balance arms have a different end point than the rest of the balance screws that looks similar to meantime screws. Better to ask before mucking about and wrecking things.
This movement has been cleaned and oiled by myself and is pushing over 300 degrees of amplitude dial up and down with a new alloy spring, so nothing to worry about there.

It’s actually a very impressive runner for being a lower quality movement of 111 years of age.
 

Skutt50

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Mar 14, 2008
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One more thing you can check;

Have a close look at the hairspring where it passes the reguator pins. Is it centered perfectly or leaning against any of the pins more than the other. If so this will speed up the balance since the effective length of the hairspring is slightly reduced.
 

JuliusSqueezer

Registered User
Mar 17, 2021
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One more thing you can check;

Have a close look at the hairspring where it passes the reguator pins. Is it centered perfectly or leaning against any of the pins more than the other. If so this will speed up the balance since the effective length of the hairspring is slightly reduced.
One of the first things I checked on this watch was the Regulator Pins for straightness and Hairspring clearance.
I didn’t see any issues and there are no major positional rate errors.
Dial Up and Pendant Up are 5 seconds apart with the all other vertical rates within 15 seconds of that, even Pendant Down, oddly enough.
 

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