Rolexman Posted December 21, 2010 Report Share Posted December 21, 2010 I'm having some problems with my vibrograph (MTG) lately.... or it could be the watches I'm measuring? What happens is (in this case both ETA 2892 and a 2671) E.G. -In the dial up position the amplitude is say 270 and the rate is +20 seconds fast -In the crown down position the amplitude drops say to 255 (-15 degrees) but the rate also decreases to + 5 seconds fast I can't find the logic. Lower amplitude means shorter balance swings which should lead to a higher rate?! No? So either there's is something I'm missing or my MTG has to be recalibrated? Would love to here some thoughts! Link to comment Share on other sites More sharing options...
FxrAndy Posted December 22, 2010 Report Share Posted December 22, 2010 Well the watch should run slowwer in crown down but that is a big change what is your beat error? do you have another vibrograph you can make comparisons with any where near you? Link to comment Share on other sites More sharing options...
RWG Technical Posted December 22, 2010 Report Share Posted December 22, 2010 E.G. -In the dial up position the amplitude is say 270 and the rate is +20 seconds fast -In the crown down position the amplitude drops say to 255 (-15 degrees) but the rate also decreases to + 5 seconds fast I can't find the logic. Lower amplitude means shorter balance swings which should lead to a higher rate?! No? Yes and no, lower amplitude can mean shorter swings and a faster rate, but you are not considering the position of the regulator pins and the position of the hairspring when the movement is placed in different positions...that is more critical than the swing length, after all our balances and hairsprings are designed to have isochronosime between full wind and unwound. So, lets say in the DU position the regulator pins are touching the hairspring all the time, and it's running +20 sec/day... Now, you move to the CD position, the amplitude is supposed to lower, but at the same time, the hairspring is not touching the regulator pins because of gravity, or only partially touching the pins as the hairspring winds up and unwinds...what has happened? The effective length of the hairsping has increased, increased hairspring length = slower vibrations... So it's possible, you have to look beyond the readings and check out the regulator, I suspect you will find your answers... (hint, use a 10X loupe and watch the regulator pins where the hairspring passes through it, look carefully in all positions to see what is happening). Good luck. Link to comment Share on other sites More sharing options...
Rolexman Posted December 22, 2010 Author Report Share Posted December 22, 2010 Well the watch should run slowwer in crown down but that is a big change what is your beat error? do you have another vibrograph you can make comparisons with any where near you? Beat error is perfect 0.1 and 0.3. Unfortunately no back up Vibrograph.. I'm on my own as no watchmaker in my neighbourhood likes home-taught watchmakers. The snobs! I do however was under the impression that crown down leads to a higher beat-rate (more friction on the balance staff ergo lower amplitude). At least all my 2836 movements act this way.. Yes and no, lower amplitude can mean shorter swings and a faster rate, but you are not considering the position of the regulator pins and the position of the hairspring when the movement is placed in different positions...that is more critical than the swing length, after all our balances and hairsprings are designed to have isochronosime between full wind and unwound. So, lets say in the DU position the regulator pins are touching the hairspring all the time, and it's running +20 sec/day... Now, you move to the CD position, the amplitude is supposed to lower, but at the same time, the hairspring is not touching the regulator pins because of gravity, or only partially touching the pins as the hairspring winds up and unwinds...what has happened? The effective length of the hairsping has increased, increased hairspring length = slower vibrations... So it's possible, you have to look beyond the readings and check out the regulator, I suspect you will find your answers... (hint, use a 10X loupe and watch the regulator pins where the hairspring passes through it, look carefully in all positions to see what is happening). Good luck. Will check it out tomorrow. Thanks for chiming in Zig. Much appreciated! Link to comment Share on other sites More sharing options...
RWG Technical Posted December 22, 2010 Report Share Posted December 22, 2010 I'm on my own as no watchmaker in my neighbourhood likes home-taught watchmakers. The snobs! Your a "home-taught watchmaker"...well had I know that that it would have changed everything...that's the last time I help you out...snob... I have one in my city as well, a SNOB watchmaker, but he prefers to call himself a "Horologist"...he's a dumbass and snob and knows squat about watches...his life is one of replacing watch batteries in quartz. I called once and asked him if he had a stem for an ETA 2671, and he had no clue what type of movement that was...other than to say it was such a low quality movement that he wouldn't even work on it, or have a stem that would fit...so much for being an expert... Link to comment Share on other sites More sharing options...
Rolexman Posted December 23, 2010 Author Report Share Posted December 23, 2010 Your a "home-taught watchmaker"...well had I know that that it would have changed everything...that's the last time I help you out...snob... I have one in my city as well, a SNOB watchmaker, but he prefers to call himself a "Horologist"...he's a dumbass and snob and knows squat about watches...his life is one of replacing watch batteries in quartz. I called once and asked him if he had a stem for an ETA 2671, and he had no clue what type of movement that was...other than to say it was such a low quality movement that he wouldn't even work on it, or have a stem that would fit...so much for being an expert... To hell with the 'Horlogists'... home-taught rules Checked the regulator pins and they are fine. Just some nice touch and release of the hair spring. Looked in to the whole isochronisme and per definition it would mean that no matter what amplitude rating I would get, it will or should not affect the rate... So if amplitude does not effect the rate what does? The lenght of the hair spring! And this is only altered by the regulator. So back to square one These technical things just grind through my mind the entire day. I will find the answer eventually Link to comment Share on other sites More sharing options...
RWG Technical Posted December 23, 2010 Report Share Posted December 23, 2010 Hmm... interesting results. If the hairsping is not touching anything and has the same contact with the regulator pins in all positions, I am not sure what is causing the problem. The balance should swing very close to the same rate, so that leaves only the hairspring changing length or maybe a coil is touching or not touching...you will find the answer, let me know when you do... Link to comment Share on other sites More sharing options...
Rolexman Posted January 2, 2011 Author Report Share Posted January 2, 2011 Update: I enountered two things that caused some problems. A balance cap leaked oil which contaminated the hair spring and thus making the coils stick. On the other movement it was the end-shake... The balance cocks could not be screwed down propperly because the balance would stop (ergo to much pressure on the staff. So I made a small 'pics ear' and voila. Both amplitude en timing problems solved! I still didn't figure out the whole isochronisme, amplitude and rate relation and how they interact.. Link to comment Share on other sites More sharing options...
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