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bsoderling

Regular erratic behaviour in Perfecta movement

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Hi,

 

Been servicing a Perfecta 151 movement lately.

 

Runs well with good amplitude but every appr 15 sec the timegrapher traces go wild for a sec or so.

 

I suppose this must be related to something bad in the higher speed parts i.e. Escapement wheel but can’t find anything from visual inspection of the wheel, pallet fork etc.

 

Have attached a screen shot from the timegrapher app on my phone.

 

Any thoughts towards where I should look extra carefully?

 

cbadc13c797f913e7a7c5cf44fbe147c.jpg

 

 

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You're way out of beat by the looks of it. Make sure the impulse jewel is lining up between the banking pins dead center so it falls on the straight line between the balance staff and the pallet fork pivot. You can do this by adjusting the hairspring collet or, if you have one, a beat correcting lever similar to a regulating lever. I don't know what is causing the intermittent erratic behavior, but I have a hunch that it may be a gear tooth that is having issues, or the watch is overbanking somehow. Start by getting in beat and inspect your escape wheel.

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Hi and thanks,

Should have mentioned this but forgot...

I actually managed to stop the recording during one of these erratic instances when also the beat error goes crazy. During the ”normal” longer operation periods, the beat error is




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And I was suspecting overbanking but the phenomena is similar at low mainspring tension and much lower amplitudes.

I will take out the escape wheel and see if I can take a few hi-res photos to post.




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Oh okay. Thanks for clarifying.

I look forward to seeing the photos. I'm not familiar enough with the movement to say exactly what the problem is with my current info, but we'll get to the bottom of it.

I also want to mention that sometimes the apps on phone based timeghraphers aren't necessarily processing the sound at the exact time the sound is made.

The processors do one thing at a time, and the app waits for a time slot to move to the next function as the phone is running all of its OS programs.. This can make timegrapher apps act oddly unless you have a "real time OS" as on a laptop or desktop.

Does the watch have the same pattern on a different timegrapher? And can you audibly hear anything different during these cycles?

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14 hours ago, Wiseman501 said:

I also want to mention that sometimes the apps on phone based timeghraphers aren't necessarily processing the sound at the exact time the sound is made.
The processors do one thing at a time, and the app waits for a time slot to move to the next function as the phone is running all of its OS programs.. This can make timegrapher apps act oddly unless you have a "real time OS" as on a laptop or desktop.

No real time OS is needed for a timegrapher application. It *could* be needed if there was a real need to guarantee time bounds between acquisition, processing and display, as in some industrial, scientific or militar applications, but there is no such need for a timegrapher, all what matters is that there is enough CPU to do the very simply stuff it does. 

Demonstration: even when running something else like video streaming, test a "bad" watch and it will show poor pattern (as in this case), test a good watch and it will show good pattern.

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Well... It may be true that the variations may be within tolerance for most horological applications, but it depends heavily on what device you're using and how it allocates processing time. There IS an undeniable fluctuation, even if it's by a fraction of a millisecond on a good device.

At least at the time I researched this and compared a dedicated timing machine and PC based software to an app on a phone, it gave conflicting results and the general consensus was that the technology was a decent indicator, but not precise enough to beat the other options.

I mentioned it mainly as a trivial addition to the knowledge base since it may come in handy sometime. I didn't do it to rain on anyone's picnic.

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Hi,

I do appreciate any views and comments over the various timegrapher options available.

I have previously reached out for comments and inputs on the Iphone version I still use and the question over the real-time properties is probably a valid one and may be so for a Windows based pc-solution as well. Who can know much about what’s going on under the cover in any such system?

In this case I do believe that the Iphone is showing reasonably well that something is not right and that it’s intermittent over a very short period.

As promised here are a couple of blow-up’s of the escapement wheel that may (?) be the cause for weird behaviour in my movement.

My untrained eye can’t really see anything totally bad (except a lot of dust and debris...)

Grateful for any sharper eyes and feedback.

540bde42ac9205feecd2b6f5aee67920.jpg9160be7351ffaec77fbdad6885dee4a7.jpg95462f26f84fccca0e4a0dbbc05305bc.jpg


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I have totaly missed this post but lets give it a go.
Your escape wheel looks dirty but it isn't causing the pattern you see on your timegraph, except from the beat error the pattern looks much like a "sticky hairspring" the phenoma can come from oil or magnetization of the hairspring or a bad end curve on the hairspring.
A bad pinion on the escape wheel should show a more slalom like pattern  with almost equal up and down humps since it is oscillating.
Here you can see a similar but in beat pattern and a quick fix since this time it was caused by old oil.
Hope this takes you a bit further.

 

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Good point about the hairspring. I guess I didn't think of that because he says it's such a regular period between issues. A hairspring wouldn't initially come to mind as something that regular over so many seconds... -_(^_^)_-

At any rate, now he has some good info to go on. I look forward to seeing where this goes.

Good luck, OP!

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Cleaning the HS is the best approach, No sense trying to go any furthure without a good clean.

I double check the pinion on escapewheel besides the teeth. Lower or raise the third wheel pinion to interface the third gear with fresh section of escape pinion. Give the escape teeth a generous oiling, this may ease the effect of the fault.

A final  re clean- oil is in order anyway.

Good luck.

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Cleaned, de-maged and checked h/s for stickyness. Nothing to be observed from that.

Did another test you may comment on.

With balance removed, I gently nudged the pallet fork side to side to start the release-lock operation.

At a couple of close to each other positions on the escape wheel circumference this is not functioning as I believe it should.

It all happens fast and is hard to observe but I think there is a ”skip over” where the locking doesn’t happen as it should but locking is happening on the next tooth.

As escapement teeth look decent, could this be a case of pallet jewel position on the hairy edge?






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If you are set up, a video replayed slow, would reveal what is going on.

If you are thinking, Pallet jewel position a hairy edge, you can  lower or raise the escape wheel.

I keep in mind, the fork interfaces functionally at both ends, pallets and horn. , if it is happy at impulse jewel side, I wouldn,t touch the fork.

Good luck Pal.

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46 minutes ago, Nucejoe said:

If you are set up, a video replayed slow, would reveal what is going on.

If you are thinking, Pallet jewel position a hairy edge, you can  lower or raise the escape wheel.

I keep in mind, the fork interfaces functionally at both ends, pallets and horn. , if it is happy at impulse jewel side, I wouldn,t touch the fork.

Good luck Pal.

   how do you slow down a video?  vin

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B,

just a thought.  If the issue is occurring at regular intervals, I.e. 15 seconds!  Start at the second hand to see if it is touching the face or has a bent pivot.  If not, move to the wheel to which it is attached.  (Sorry, I do not know my wheel names and functions).  If that wheel and it’s pivots are fine, follow the threads,( an IT term meaning follow the chain of events) until to find the problem.   

If it happens at regular intervals, watch the things that happen at those intervals.

just my opinion.

 

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