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east3rn

help on Bifora 910 movement/ troubleshooting

Question

Hello dear watch repairers.

I am working on a Bifora 910 manual wind movement.

The movement was cleaned and oiled yesterday and I have been testing the performance.

I noticed that when the watch is fully wound, the amplitude reaches somewhere above 300 and rate gets super high.

However after about 5 minutes, both amplitude and rate plunge to a very low state.

I thought mainspring was the reason so I took the barrel out, cleaned the mainspring and applied 8200 oil again only to get the similar result.

What do you think is the problem and what can be done??

I am always thankful for your help.

KakaoTalk_20181208_224154636.jpg.43a00e0a9a7faeffc2aa944d06fb8338.jpg 

this is when fully wound

KakaoTalk_20181208_224154181.jpg.33542433a3482976d3fa52eccc2a1d16.jpg

After 5 minutes

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I would say you have a hairspring issue. Looking at the first pic it is running incredibly fast. It might just be magnetised which causes the  coils of the HS to stick together. If is not magnetised if it was me I would remove the balance and clean in a degreaser and dry. Then re-lube the cap jewels. This type of fault is a matter of elimination.

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10 hours ago, oldhippy said:

Have you cleaned the watch in a watch cleaner? If so did you take apart all the shock from the balance, if so have you put it back correctly? No oil on the pallet pivots.

 

 

5 hours ago, clockboy said:

I would say you have a hairspring issue. Looking at the first pic it is running incredibly fast. It might just be magnetised which causes the  coils of the HS to stick together. If is not magnetised if it was me I would remove the balance and clean in a degreaser and dry. Then re-lube the cap jewels. This type of fault is a matter of elimination.

Yes. I cleaned the whole assembly and oiled cap jewels on both ends.

I should give another try. I will let you know the result. Thank you. 

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19 hours ago, east3rn said:

thought mainspring was the reason so I took the barrel out, cleaned the mainspring and applied 8200 oil again only to get the similar result.

A little clarification you Cleaned the watch did you disassemble the watch when you cleaned it? Then the mainspring are you using a new mainspring or the old mainspring?

Then when the watch is fully wound up do you mean fully wound up as tight as you can get it or just wound up until it stops?

What was the watch doing before you took it apart and cleaned it?

Timing machine diagnostic is very useful but sometimes it's kind of like reading a crystal ball it's not always an exact science if we don't have the proper background knowledge of what's going on with the watch. For instance when it's wound up tight the machine Numerically says it's in beat but the dots don't look like they're in beat? Then visually when you were assembling the watch did you check to make sure the watch actually is in beat? When the balance wheel and pallet fork were out did you check for Back spin?

Also helpful for diagnostics is more than one position on the timing machine. The typically dial-up and dial down and at least one crown/pendant position. As this is a wristwatch crown down would be fine.

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On 12/9/2018 at 6:59 PM, Watchtime said:

looking forward to what happened....

 

On 12/9/2018 at 3:58 AM, clockboy said:

I would say you have a hairspring issue. Looking at the first pic it is running incredibly fast. It might just be magnetised which causes the  coils of the HS to stick together. If is not magnetised if it was me I would remove the balance and clean in a degreaser and dry. Then re-lube the cap jewels. This type of fault is a matter of elimination.

 

On 12/9/2018 at 6:46 PM, JohnR725 said:

A little clarification you Cleaned the watch did you disassemble the watch when you cleaned it? Then the mainspring are you using a new mainspring or the old mainspring?

Then when the watch is fully wound up do you mean fully wound up as tight as you can get it or just wound up until it stops?

What was the watch doing before you took it apart and cleaned it?

Timing machine diagnostic is very useful but sometimes it's kind of like reading a crystal ball it's not always an exact science if we don't have the proper background knowledge of what's going on with the watch. For instance when it's wound up tight the machine Numerically says it's in beat but the dots don't look like they're in beat? Then visually when you were assembling the watch did you check to make sure the watch actually is in beat? When the balance wheel and pallet fork were out did you check for Back spin?

Also helpful for diagnostics is more than one position on the timing machine. The typically dial-up and dial down and at least one crown/pendant position. As this is a wristwatch crown down would be fine.

 

Hello. I've been busy all weekend and could allow myself some time to work on the movement.

I disassembled the upper/lower balance jewels, cleaned and oiled them again.

I think the graph is much better except for the fact that amplitude is still way low...

For this time I added more photos of timetesting. I had no idea that much more things were related to timekeeping!

**I want to know what is a back spin and how to check it please. 

KakaoTalk_20181211_091211525.jpg

KakaoTalk_20181211_091211916.jpg

KakaoTalk_20181211_091212392.jpg

KakaoTalk_20181211_093339999.jpg

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I'm being sidetracked with other projects I  thought I'd check in and see how you doing?

Then regarding the question of backspin this is a discussion group did you do a search to see if that term ever came up before? So one of the ways to tell if you gear train is free with the pallet fork removed balance wheel removed. You start to the wind the watch and with nothing to hold the gear train in place it will start to spin once it's spinning you stop winding. The momentum of the gear train will go past where the mainspring is powering it and the momentum will wind the mainspring a little bit backwards. Once it runs out of energy that back wound mainspring will pull the gear train back. So if you look very carefully you'll see the train come to a stop and then go back just a little bit. That's usually an indication that the gear train is incredibly free and you probably won't have a problem.

then minor problems with backspin it doesn't work with all watches. The link below has what I believe is your watch and looks like a spring is over the sweep second wheel? That might be enough to interfere with backspin.

Then for the pictures at the link below this doesn't appear to be a super high grade watch? At the very end of the article the timing machine results look horrible to be honest.

A minor note regarding timing machine results? Unfortunately we don't have cheap artificial intelligence yet so that we can build a timing machine that tells us in audio terms what's wrong with the watch. So the meeting of this is timing machines are kinda like a crystal ball, okay there actually better than a crystal ball they do work with scientific principles but interpreting the results sometimes is a little bit vague basically it just points us in a direction. Then it requires the user to use their eyes and skills to look at the physical watch which we can't do we rely on your pictures and we can only point you in a direction.

so the timing machine isn't going to give all the answers for instance? for instance the watch running when it's fully wound up super tight and shortly later crashes and burns timing machine is it going to help with fact. then isn't this interesting resting on the pivots it's running fine and everywhere else you lose a lot of amplitude? So you need to look very carefully at the balance pivots and the jewels. As her seems to be an issue with their balance wheel as far as the timing machine can tell.

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Thanks John I have never noticed the backspin but will look for it now. :Bravo:

I think the key to these types of fault is when assembling is to check as you go. I always for instance check for free play and end shakes after assembling the train of wheels. When assembling the keyless side again I check all is well as I go. Finding something is wrong on the final test is annoying to say the least.

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