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Movement Running 4 Seconds / Minute Fast

Bike Mike

By Bike Mike
in Movement Q&A

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Bike Mike Newbie

Bike Mike

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Yes I said 4 seconds fast per minute! Alright...So last night I ran a 28.8K A7750 through the cleaner and reassembled it this morning. Timed it out to +2 sec/day average in 3 positions...Put it all back together and threw it on my wrist...1 hour later looked at the time and said "WTF"...it is 4 minutes fast. Threw the entire watch back on my timer and still was running +2sec/day. So I took the movement out of the case and tore it back down to the base train...Put the movement on the timer and stil +2sec/day. Again WTF???

I then timed the second hand to go around the dial once with a stop watch and it took 56 sec. I know this is possible if some gear teeth are missing and the train is slipping, but that is just it...My timing machine is showing no noise in the gear train. Each wheel, tooth, pivot, etc checked out fine. The sweep second hand, sweeps nice and smooth, (no jumping like you would have with broken teeth). The palet fork jewels have good engagement to the escape wheel and so on...So I am clueless as to how the movement is timing out perfect, yet timing the second hand move around the subdial with a stop watch is 4sec/min fast... :whistling:

Any ideas, because this defies everything I know and have been taught about watch regualtion...Can't wait to bounce this one of my watch maker tomorrow.

:drinks:

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Bike Mike Newbie

Bike Mike

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Check the balance, specially the mainspring...

Francisco, you mean hairspring right? Not "mainspring"...Anything specific I should check for in the balance assembly? The only thing I have not checked in the balance yet is to make sure the roller jewels and impulse stone in sitting nice and tight to the assembly. I already adjusted the hair spring making it nice and concentric with no coils touching.

I thought at first maybe the balance we just oscillating at a insane rate of speed, but if that were the case the timer would detect that. With my timer set to “Automatic Beat Rate Detection” it is purring along at 28.8k bph.

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Bike Mike Newbie

Bike Mike

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If it wasslow i would say the clutch is slipping but fast????

I will ask my mentor when i see him tomorrow evening

I would agree...the whole running fast thing has got me really questioning how this can be...if some teeth were missing in the gear train...absolutly. But you would also see that on both the timer and visually. The running second hand is running smooth!

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FxrAndy Newbie

FxrAndy

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Ok the thoughts from my watchmaker/mentor and my coments back to him in red

check the beat, he says that the beat is correct

check magnetism, could be how would this make it run faster though unless a coil on the unrue was touching

check the Balance spring, is round and not touching

if you have problems with the clutch(train) the movement would be in the right time but the hands are slower, I agree

It is possible a Spring winding is connected the beat rises up and the watch goes forward.

it looks being correct in time and it is correct but in the wrong beat.

I keep thinking that if the movement was the older beating at 21600 and you put a balance out of a newer one beating at 28800 what would happen??????????????????

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Nanuq Mentor

Nanuq

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A 28800 balance running in a 21600 movement would produce a watch operating at 1.33x normal speed, gaining 20sec in a minute. Correct?

I bet the beat/amplitude is way too large so the escapement is grabbing an extra tooth periodically. That wheel turns forward one extra tooth, movement leaps forward an entire extra notch, making it run fast... while the beat period stays the same.

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FxrAndy Newbie

FxrAndy

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A 28800 balance running in a 21600 movement would produce a watch operating at 1.33x normal speed, gaining 20sec in a minute. Correct? Not sure Bob i dont think it is that fast but i dont know how to work the math out being a thicky, it is only i beat, 12.2% faster i think with the rough maths i have done but thst is assuming that the gear train for both movements are the same

I bet the beat/amplitude is way too large so the escapement is grabbing an extra tooth periodically. That wheel turns forward one extra tooth, movement leaps forward an entire extra notch, making it run fast... while the beat period stays the same. It would be letting an extra tooth on the escape go rather then grabbing but the amplitude for that to happen would cause the movement to over bank and that would be apparent on the viborgraph, also if the amplitude was so large chances the movement would be running slow due to the time taken from one swing to another

A missing tooth or teath would alow the movement to jump forward a bit but again that would be visible on a vibrograph

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Bike Mike Newbie

Bike Mike

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Ok the thoughts from my watchmaker/mentor and my coments back to him in red

check the beat, he says that the beat is correct

check magnetism, could be how would this make it run faster though unless a coil on the unrue was touching

check the Balance spring, is round and not touching

if you have problems with the clutch(train) the movement would be in the right time but the hands are slower, I agree

It is possible a Spring winding is connected the beat rises up and the watch goes forward.

it looks being correct in time and it is correct but in the wrong beat.

I keep thinking that if the movement was the older beating at 21600 and you put a balance out of a newer one beating at 28800 what would happen??????????????????

Beat checked...28.8K

Magnatism...I always de-mag. the balance before install and after assembly.

Balance hair spring...Concentric, no twists and level. Perfect in everyway.

Clutch...I agree on the clutch, if it was slipping the hands would be slower but it is not even engaged. I have the movement torn down to the base gear train. I have the second hand on the 2nd wheel post. The second hand rotates once about every 56 seconds.

A 28800 balance running in a 21600 movement would produce a watch operating at 1.33x normal speed, gaining 20sec in a minute. Correct?

I bet the beat/amplitude is way too large so the escapement is grabbing an extra tooth periodically. That wheel turns forward one extra tooth, movement leaps forward an entire extra notch, making it run fast... while the beat period stays the same.

As Andy said, this would be easily seen on the timing machine. I have seen before a pallet stone was just a little too short. The escape wheel would just hit the "cut" face of the stone causing a beat to register on the timing machine. This created noise and caused the movement to run really fast...both stones on the fork have good engagement.

Thaks for the link...this is where I ended up after today. I discussed it with my mentor and he actually called his mentor and long time teacher in for tomorrow to look at my movement.

We did discuss that maybe some thing in the train has the wrong tooth count. Which is feasible, but the gear pitch would possibly not mesh. The second wheel is a brand new ETA second wheel. If it had a different tooth count then the original, then the gear mesh would be off. I did count the teeth on the new second wheel and it had the same number of teeth on the old one.

So if this issue is coming from extra teeth in one of the wheels (which I am leaning towards as everything else has checked out okay) this is showing 2 things.

1.) The Asians are making 2 sets of gear trains that have different gear ratios through the train to escapement.

2.) They have done it in a way to keep the gear pitch the same meaning that worn parts will be harder to swap and you would have to replace every wheel in the train or you end up with the issue as I do.

I love finding this stuff out with these Asian movements. :bounce: Looks like I am doing a bunch of teeth counting tomorrow. :bangin:

Thanks for the input guys! :drinks:

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Bike Mike Newbie

Bike Mike

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That's your answer...the tooth count either in the pinion or the wheel is different than the Asian one.

Overall the ratio would be the same btwn an ETA and an Asian 7750 @ 28.8k, BUT, the ratio's between each of the wheels is most likely not the same...

Alright The Zigmeister chimed in :thumbsupsmileyanim: ...This was my original thinking. But then I figured if that was the case, how are the gears even meshing because the diametral pitch would be off with either the Wheel to the Escape or the pinion to the Third wheel, not allowing the movement to run. Maybe I just got lucky, so I took the ETA Second Wheel out and install another Asian second wheel that I had with a busted second hand post and I got the same results. 4 seconds/minute fast.

So I decided that I would go blind and start counting teeth between the movement giving me the issues and a spare set of gears I had form a scrapped movement....I made it through the main spring barrel, great wheel and third wheel. Some number of teeth on the movement I had vs. my spare parts. Looked at the second wheel and said "Sh*t I threw out the original second wheel! :bangin: F**K!!!" However given the spare Asian Second wheel gave the same results as the ETA one, I assumed the teeth were the same...So I said, "To hell with this, I am replacing the entire gear train!"

No doubt this should fix my problem as I believe it is in the gear ratio...but I just can't get past the fact, that if it was indeed the gear ration...

1.) The differences between the ETA second wheel and the Original Asian, should have prevented the movement from functioning due to the difference in diametral pitches. But say I got lucky some how and the stars were in alignment that leads me to point #2.

2.) The spare Asian second wheel I have yielded the same results as the ETA one...given this, it seems there are 2 gear train ratios of 28.8K Asians movements. One ratio would be the same as the ETA ratio. The other ratio will be what is in the current movements I have the problem in.

:drinks:

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RWG Technical Newbie

RWG Technical

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I have seen some bizzare things with the A7750's...

I remember washing 2 movements and simply mixing up all the parts in the baskets, it didn't matter as they were identical movements...right?... WRONG...

I found out the hard way, the parts were all slightly different, I didn't get into counting all the wheel teeth, but not one of the wheels fit in the jewels in each mainplate and it took me hours to get all the parts in their respective corners.

I have also had similar train, balance, problems with older rollie's, i.e. a 18K train with a 19,8K balance, or vice versa, a real mess to sort out.

Also check the pallet stones, they tend to be loose and could mess up the reading on the pickup of the vibrograph.

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