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Author Topic: Quick Regulation Question  (Read 1844 times)
husbandofemily
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« on: September 03, 2013, 12:35:52 pm »

Hi all (it's me again...)

My better half bought me a lovely shenhua wristwatch for my birthday, and although it was accurate for a week or so, has started gaining a few minutes a day. I think this is due to me forgetting to remove it before being daft on our trampoline with the kids, I reckon I've knocked it, and so the regulator, out a bit.

Now, I've read up on what I'm meant to do, and I'm happy for the most part. One (crucial) part I need to check though - which is the regulator bar and which is the isochronism bar, which I know I'm not to touch.



I'm almost certain it's lever 'A'. Almost. Are the number of dots for each lever consistent across watches; a convention amongst watchmakers? Some of the "how to" articles online show to move the uppermost of the two, and there's no +/- stamp to help me.


I'm asking on here instead of a watch forum as my watch is a "steampunk" watch - there's more chance someone has seen/worked on/trashed one before here  Wink.

Any help appreciated, thanks  Smiley
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Abslomrob
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« Reply #1 on: September 03, 2013, 01:51:44 pm »

You're the second person in the past month I've encountered that describes the stud carrier as an "isocronism lever".  Curious, someone out there is making up words.  "B" in your picture is the mobile stud carrier.  "A" is the regulator.  The number of "dots" on the levers is a  function of what's on the other side of them.  The stud carrier is a single "pin" that is used to attach the end of the hairpsring.  The regulator has two pins that extend down on either side of the hairspring, and serve to (effectively) change the length hairspring.

 Moving the stud carrier allows you to put the balance "in beat".  In beat effectively means that if the balance was still, the impulse jewel (which is underneath the balance) would be perfectly centered on a straight line that connects the pivot of the balance to the pivot of the escape wheel.  Of course, you can't actually confirm that without dismantling the watch.  If you had a "watch timer" you'd be able to see it on the display, and some people people claim they can "hear" when a watch is out of beat (the time between each "click" should be the same).  Note that while you can sorta argue that since it ensures that the time for each "tick" takes the same amount of time that "isochronism" is a suitable description, it's not a good idea to use the word such since that's different then how "isochronism" is viewed for watches in general, and it's just going to confuse people that actually know what they're doing.

If the watch is losing time after only a week, chances are it was never oiled properly to begin with.  it's unlikely that "jumping" would have changed the lever positions (and if it did, the lever is to loose to be useful anyway).  This looks like a fairly simple chinese movement, and often they get put into cases by profit-conscious companies without being properly oiled.  Likely, it just needs a good service.  Try to watch the balance wheel carefully; if you focus, you should be able to see the points where the balance wheel stops and starts moving the other way by watching the arms.  From that, try to get an idea of how great the amplitude is.  One problem I've had with chinese movements is that they use a cheap, light metal for the rotor which isn't able to wind the mainspring more then about half before the force of the mainspring is greater then the force of gravity acting on the rotor.  This prevents the balance for getting a good amplitude and makes it run fast when you take it off overnight. 
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All my vintages are at http://www.abslomrob.com
husbandofemily
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United Kingdom United Kingdom



« Reply #2 on: September 03, 2013, 07:25:41 pm »

Aslomrob - I do love hearing somebody talk about something they truly understand!  Cheesy Thanks for your help - First up I suppose it paying more attention to exactly when it's making time; if it is at night I've found my gremlin.

Also, I read somewhere that placing the watch on it's side, winding handle down, can slow it down some. Have you heard that before? On the subject of believing what you read online, I couldn't tell you which site referred to it as a "isocronism lever", but I'm glad I'm not the only one  Wink. Apologies for any confusion.

As for the balance wheel, thankyou for giving me the most hypnotic 5 minutes trying to figure it out - even in daylight to avoid the stroboscopic effect I'm struggling to see the amplitude of the oscillation. Somewhere between 45 and 60 degrees - maybe?? Whatever, staring at the working innards of the was very relaxing  Smiley

Incidentally, I used a digital stopwatch, and it's gained one second in 3 hours. So far, all signs point to overnight? A pre-emptive bravo for the clock-whisperer there  Cheesy

I'll let you know how I get on, thanks again for your help.

Ian
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Abslomrob
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« Reply #3 on: September 04, 2013, 12:00:35 am »

The position of the watch will normally cause a difference in the beat rate, for several reasons (depending on the watch).  Most notably,a watch that is "dial up" or "dial down" will have the balance pivots resting on the bottom cap jewel.  This is (typically) the position of lowest friction, since the balance is essentially spinning like a top on a very small point.  Gravity is pulling the hairspring up or down, so there's no problems with the breathing.  When you turn the watch onto it's side, now the balance pivot is resting against the side of the top and bottom pierced jewel.  That increases the friction, which in turn will decrease the amplitude and thus make the watch run a bit faster.  Also, if the regulator pins aren't shaped correctly, the effect of gravity on the hairspring may cause it to change its effective length, resulting in a unexpected change of rate.  The comments above also impact the other wheels to some degree, but the difference in friction simply causes the amount of energy being transferred to the balance to change, which changes the amplitude.  But since these gears are all under constant force, they're always pushed against the side of the jewels anyway.  Cap jewels on the gear train simply ensure that the "shoulder" of the pivot isn't rubbing against the jewel.

From what you're describing, the problem sounds like it's caused by the mainspring not winding up enough.  When you take it off overnight, the power from the mainspring starts to drop off quickly which will (normally) cause the watch to start running fast.  But if hte problem is that it runs slow, that's normally increased drag on the balance pivots caused by dry pivots and dirt.
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