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Timegrapher Says, +/- 8S/d. Real Life Shows Fast By20 Secs/min

Legarm

By Legarm
in Watch Repairs Help & Advice

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ChrisN Member

ChrisN

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If you have too strong a mainspring then you're likely to get very high amplitude (which you don't have) and knocking. This sounds like a horse galloping when you listen to the watch. Even then, I wouldn't expect the rate to be more than half an hour per day, which is only 2% fast not 33% fast.

It does seem you have a 3Hz/4Hz issue as 80 secs in 60 secs is exactly 4/3...

I don't know this movement but, assuming the seconds hand is indirectly driven and you have a 4Hz balance/escape (28800), the timegrapher would show 28800 and the minute hand/hour hand should move correctly. Is that the case? Try timing the minute hand for 9 minutes and see if it moved 12 minutes.

Could it just be that the second hand pinion has an incorrect number of teeth (or whatever wheel drives it). If this pinion was from a 3Hz movement for example? So, the movement plus minute and hour hands runs at 28800 correctly and the second hand runs 4/3 fast.

Good luck, Chris

Sent from my XT1039 using Tapatalk

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StuartBaker104 Distinguished Member

StuartBaker104

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Legarm,

With you timegrapher set to auto, if the beat rate comes up as 28800 then your escapement is running too fast. As others have said, this is unlikely to be a mainspring problem unless it is making nasty noises.

Check the hairspring. Are any of the coils touching each other? If so, it could be dirty or magnetized (hence the question above about rheumatism bracelets). Also, make sure that the second coil of the hairspring is not touching the regulator boot.

If the hairspring is good, i would suggest you check the train count to make sure you have all the right wheels. There is a calculator at the bottom of this page http://www.vintagewatchstraps.com/watchmovement.php. You know the answer should be 21600, so this should help you diagnose which is wrong.

S

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agoldflam Member

agoldflam

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Nifty problem, just did a 2688 today that someone put in a lds date just, ugh, so I would confirm safe drop on all pallet jewels and figure out that amp problem, most likely mainspring but could be end shakes for balance or pallet staff, insetting also I seem to remember them different for upper and lower on 2871, and I think it's 28800 with 51 lift angle just confirm its set to that, with 226 I'm skeptical of +-8 so I would double check that, and make sure hairsprings not sticky! To many possible answers I guess... Good luck!

Through watchmaking I restore connections in people's lives!

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Legarm WRT Addict

Legarm

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Nifty problem, just did a 2688 today that someone put in a lds date just, ugh, so I would confirm safe drop on all pallet jewels and figure out that amp problem, most likely mainspring but could be end shakes for balance or pallet staff, insetting also I seem to remember them different for upper and lower on 2871, and I think it's 28800 with 51 lift angle just confirm its set to that, with 226 I'm skeptical of +-8 so I would double check that, and make sure hairsprings not sticky! To many possible answers I guess... Good luck!

Through watchmaking I restore connections in people's lives!

 

2871 lift angle is 52

 

Data

11.5''', Dm= 25.6mm, Do= 26.0mm

H= 5.35mm

(dial spacer +0.15mm)

F= 0.6mm

T= 2.3mm

17/21/25 jewels

f = 21600 A/h

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Legarm WRT Addict

Legarm

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right. Just manually put everything into the timegrapher and I now see the beat rate was auto set at 28800. Re-set it too 21600 and the movement will now not register the output as it is way too high.

I reckon someone has married two separate components in the past.

I will see what the person I bought it from has to say.

Thanks for all the useful comments and tips, if nothing else we all hav3e some new info on this complex subject.

Thanks all

Keith 

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Legarm WRT Addict

Legarm

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I'm thinking hairspring..... Maybe not clean? Maybe magnetism? Maybe oil got on it?

If the mainspring was in the watch before .... Well it should be ok?

 

Just cleaned the  hairspring again and I am about to see if it can take any ragulation on the adjuster. If not I shall bung it on Ebay, as parts or spares. It's a realy nice watch when it is all together. 

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ChrisN Member

ChrisN

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It does sound like you have some 2870 wheels in there as its running at 28800. I don't know this calibre but, are all three hands running fast? I suspect it's just the second hand.

You can calculate thus calibres correct rate by counting the teeth on each wheel as pointed out by Marc. Here's an example for an Omega 561 where the barrel drives the second wheel which is attached to the cannon pinion so:

The second wheel large gear has 64 teeth and rotates once per hour (3600 seconds) by definition as the minute hand is connected to it via the cannon pinion.

The 3rd wheel has a small gear of 8 teeth which meshes with the large gear of the 2nd wheel. So, for one rotation of the centre wheel, the 3rd wheel rotates 64/8 = 8 times. Therefore, it rotates once in 3600/8 = 450 seconds. It also has a large gear and that has 60 teeth.

That large gear meshes with the small gear on the 4th wheel which has 8 teeth as well. So, for one rotation of the 3rd wheel, the 4th wheel rotates 60/8 = 7.5 times. Therefore, it rotates once in 450/7.5 = 60 seconds. It also has a large gear and that has 77 teeth.

That large gear meshes with the small gear on the escape wheel which has 7 teeth. So, for one rotation of the 4th wheel, the escape wheel rotates 77/7 = 11 times. Therefore, it rotates once in 60/11 = 5.4545 seconds. It also has a large gear and that has 15 teeth. This is the one that meshes with the pallet fork and so, the teeth pass the fork every 5.45/15 = 0.3636 seconds. There has been a little rounding of numbers in this paragraph for simplicity.

This tells us that this watch beats at 2.75 Hz ( 19800 A/hour = 2.75*60*60*2) as 2.75 times per second means one beat is in 0.3636 seconds.

I just copied this from something else I wrote but, it will make sense to everyone here.

If I wanted to change this movement to run at, say, 28800 A/h, I could do it just by changing the number of teeth on one or two wheels. I can't immediately see a way to do it with one as it would have a lot of small teeth.

Usually the fourth wheel runs at one revolution per minute as then we can easily mount a sub second hand on it. So, maintaining that but changing its large gear to have 96 teeth (was 77) and the small gear on the escape wheel to have 6 (was 7), it becomes a 28800 movement. Nothing else needs to change and it now runs at 4/3 speed (a bit like my life since I passed 50...)

All you need is the correct wheels from Cousins for a 2871.

Hope this help, Chris

Sent from my XT1039 using Tapatalk

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Legarm WRT Addict

Legarm

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I hope you get to the bottom of his Keith, there's a lot of folk needing the answer now. ;)

 

Just cleaned and demagged the hairspring. no difference. Lookout Ebay here it comes................ life is too short..... 

 

ChrisN

 

All hands are running fast.

 

All the train wheels from cousins make the repair, cost-prohibitive. I can't justify the added expense on this watch. I can't see how all the wheels have been changed for a completely different set up.

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ChrisN Member

ChrisN

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Ah that's a shame. Advertise it for soon to be married men. "Gets you to the church on time".

Remember, "it's not really work" - I just happen to be playing (or is that murdering?) Modern love at the moment...

Sent from my XT1039 using Tapatalk

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clockboy Distinguished Member

clockboy

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right. Just manually put everything into the timegrapher and I now see the beat rate was auto set at 28800. Re-set it too 21600 and the movement will now not register the output as it is way too high.

I reckon someone has married two separate components in the past.

I will see what the person I bought it from has to say.

Thanks for all the useful comments and tips, if nothing else we all hav3e some new info on this complex subject.

Thanks all

Keith 

See Marcs post the link he has posted shows exactly the problem you have. Someone has fitted an incorrect wheel.

This is the link he posted 

http://watchguy.co.uk/repair-heuer-autavia-buren-12/#more-10379

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