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VWatchie

Need help with Unitas 6325 amplitude problem

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I serviced this watch housing a Unitas 6325 just a month ago, and although the amplitude was borderline acceptable, 250/260 degrees dial up/dial down and about 220/230 in all other positions I decided to call it day and simply wear it and enjoy it. It definitely is one of my favourite watches as it so clean looking and so easy to read, and I paid less than $30 for it, which doesn’t hurt.

Anyway, yesterday I decided to tighten the cannon pinion because I had some intermittent problems with the timekeeping (full story here). After this I put the movement on my timing machine and the readings were bad, about 200 degrees dial up/dial down. Totally unacceptable.

So, I decided I needed to investigate. I checked the pallet stone locking (not good but not too bad), the oiling (looked just fine), the balance jewel settings (looked straight), end-shake of all wheels including the balance (I have limited experience of what is acceptable but it felt fine, tight but still moving freely with a very fine play), looked around for any dirt, dust, hair, debris under my stereo microscope but couldn’t see any, and I made sure the train was spinning freely. So, remaining to investigate, and the place where I probably should have started, the dreaded balance and hairspring. Dreaded because in this field my skill level is near nil.

What I saw looking at the balance and the hairspring is what you can see in the two above videos. As I remember it, it should be possible to move the regulator arm along the terminal curve without disturbing the hairspring. As you can see, this is certainly not the case. Also, to me it looks like the hairspring is almost pinched between the index pins of the regulator arm. To me it looks like it need more play, but I need your opinion.

When I first looked at the index pins I noticed that the outer and inner index pins weren’t exactly opposite one another, so I adjusted the outer index pin by placing a screwdriver in the slot of the boot of the outer index pin and turned it until the index pins were opposite one another (video made after this adjustment). However, this only seemed to aggravate the amplitude problem, and after this adjustment the hairspring looked even more pinched between the index pins.

So, I have a few questions; how likely is it that the low amplitude is the effect of the status of the hairspring and index pins? What can I do and what tools do I need to remedy this problem? I guess I could try to find a watch repairer but that would sort of defeat the purpose of this hobby of mine ;) Nevertheless, trying to form a new terminal curve (if necessary) would likely end in disaster, so I just don’t know… I’d hate to ruin this movement. Perhaps, that wouldn’t be needed, and I could just focus on the index pins (which I never did either but have some info about from @HSL, thank you), no?

Well as you can probably notice, I feel pretty bewildered about this, so I need you support. What’s your take on this?
 

 

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8 hours ago, rodabod said:

In Endeavour's drawing, look at Fig. 4 "depth of lock" which refers to one of the aspects which I was talking about. 

Hence my posting, to "visually" support what you said and to give VW a hold-on-to "handle" ;)

Edited by Endeavor

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11 hours ago, rodabod said:

Polish the pivot to smooth out the scoring.

Hmm... that would mean removing material and I really haven't got a clue about what kind of tools and materials would be required? I would assume the "pegwood, oil, jeweler’s rouge"-method described in this article wouldn't do the job? I guess some sort of abrasive method would be required?

Anyway, checked with cousinsUK.com and they have the third wheel for the Unitas cal. 6325 for £7 (incl. tax). Of course, I wouldn't mind saving that money if I could smooth out the scoring myself.

Edited by VWatchie

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12 hours ago, VWatchie said:

Hmm... that would mean removing material and I really haven't got a clue about what kind of tools and materials would be required?

Well, I know as little as you do about this, but Googling around a bit definitely gives me the impression that a "Jacot" tool is the way to go. I know that you have The Watch Repairer's Manual 2nd Edition by Fried, so look up page 155 where you can read "This tool undoubtedly offers one of the very best methods of reducing or polishing pivots to size and shape". Of course, that would mean yet another investment so I'd say make that a long term goal and go for the spare part for now.

Good luck!

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14 hours ago, VWatchie said:

Hmm... that would mean removing material and I really haven't got a clue about what kind of tools and materials would be required? I would assume the "pegwood, oil, jeweler’s rouge"-method described in this article wouldn't do the job? I guess some sort of abrasive method would be required?

Anyway, checked with cousinsUK.com and they have the third wheel for the Unitas cal. 6325 for £7 (incl. tax). Of course, I wouldn't mind saving that money if I could smooth out the scoring myself.

If it's only a light scratch then you may be able to rest the pivot in a groove cut into a piece of hard wood and apply some metal polish like autosol. You would then hold and slowly rotate the wheel in one hand while pressing down on the pivot with a flat piece of pegwood or similar.

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I would try replacing the cracked jewel, before doing any pivot polishing. Did you use smoothing broaches on the barrel, and what was the result? My advice is not to change anything you can't change back, unless you're absolutely sure you need to.

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7 hours ago, rodabod said:

If it's only a light scratch then you may be able to rest the pivot in a groove cut into a piece of hard wood and apply some metal polish like autosol.

Oh yes, the scoring is very light but can be distinctly seen at 40X magnification. It's looks like a countersunk ring around the pivot with a width of only a few thousands of a millimeter. Don't know what would be suitable hardwood (?), but I think I can try with pegwood and autosol first considering the scoring is so light.

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34 minutes ago, Klassiker said:

Did you use smoothing broaches on the barrel, and what was the result?

No, I haven't yet received the smoothing broaches, but once I've tried it I'll let you know the result. I'll be going very easy and I'll try not to overdo it. Hopefully it will make the barrel spin more freely around the arbor. CousinsUK doesn't have the barrel and cover as spare part so hopefully I won't be making a mess of it.

I guess as a general rule it is better not to fix it unless it is broken, but in this case I'm just too curious to see what it's going to do.

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14 minutes ago, VWatchie said:

Oh yes, the scoring is very light but can be distinctly seen at 40X magnification. It's looks like a countersunk ring around the pivot with a width of only a few thousands of a millimeter. Don't know what would be suitable hardwood (?), but I think I can try with pegwood and autosol first considering the scoring is so light.

I wouldn't be surprised if it makes little difference having that score there. It will be a "plain hole" in the jewel, so the walls are flat and parallel, so the ring will simply not touch the jewel. Unless of course the groove is the same width as the contact area with the jewel.

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1 hour ago, rodabod said:

Also, just my opinion, but from looking at your video, the freedom of movement which you are getting from the barrel when turning on its arbor is fine.

Considering the strong torque and the thicker pivots, as you explained so well a few posts ago (an eye opener to the mechanical idiot, i.e. me), I think you're absolutely right about that. Nevertheless, now that I've ordered the smoothing broaches I will still have a go with them. Hopefully it will make some (probably unnecessary) improvement and hopefully I won't be making a mess. No matter, I will likely learn something.

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I think in this thread you had a fair amount of warnings on not to alter things unless you absolutely had to and you knew the reason(ing) for doing so.

The good news is that it's a cheap movement and therefor the outcome doesn't really matter. It may become a big success or a small price to pay for all the info you get and the learning curve to be gained.

I've other project to do so I'm wishing you lots of suc6 :thumbsu:

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On 3/31/2020 at 12:24 AM, rodabod said:

If it's only a light scratch then you may be able to rest the pivot in a groove cut into a piece of hard wood and apply some metal polish like autosol. You would then hold and slowly rotate the wheel in one hand while pressing down on the pivot with a flat piece of pegwood or similar.

What I tried was place the pinion of the wheel in a suitable hole in my staking block. I then placed Autosol on the pivot and some Autosol at end of a piece of peg wood. I then held the wheel by a spoke using my tweezers while rotating the pegwood on the pivot. I repeated this several times. The result was a very well polished pivot (near but not quite mirror shine) but the method just wasn't abrasive enough to remove any material (except minuscule) so it wouldn't remove the scoring.

Anyway, with the new jewel I really don't think there's and need to remove the scoring as its so very small. The Autosol was extremely efficient for polishing though!

Edited by VWatchie

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On 3/31/2020 at 10:11 AM, VWatchie said:

Considering the strong torque and the thicker pivots, as you explained so well a few posts ago (an eye opener to the mechanical idiot, i.e. me), I think you're absolutely right about that. Nevertheless, now that I've ordered the smoothing broaches I will still have a go with them. Hopefully it will make some (probably unnecessary) improvement and hopefully I won't be making a mess. No matter, I will likely learn something.

So, I've now tried to smooth a barrel hole using my new smoothing broaches. Not willing to take any chances with my Unitas barrel I tried with a few Vostok barrels (as I have a pile of'em) but the result was not encouraging. The smoothing broach very easily gets stuck in the hole despite using a fair amount of honing oil (3-in-one oil) so it's difficult to twist the broach in any smooth/even manner. Nevertheless, I tried the best I could but I wouldn't say the hole became much smoother, if at all...:unsure:

Anyway, I've extended my set of tools with a set of 12 very fine Bergeon smoothing broaches :lol: Come to think of it, what is the main purpose of smoothing broaches? :huh:

Edited by VWatchie

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On 4/8/2020 at 1:09 PM, VWatchie said:

Anyway, I've extended my set of tools with a set of 12 very fine Bergeon smoothing broaches :lol: Come to think of it, what is the main purpose of smoothing broaches? :huh:

I'm still waiting for a reply but as far as I can tell, the main purpose of smoothing broaches is to test the efficiency of ball bearings of oscillating weights as demonstrated in the below video. Well, maybe not ;) but it's definitely a bonus :lol:

 

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So, finally my very legible Unitas 6325 ”amplitude problem child” has been re-assembled. Timing machine images below. I started the reassembly weeks ago but as I was fitting the click spring it decided to launch for outer space, never to return. Anyway, CousinsUK had the click spring in stock and delivery to Sweden usually just takes a week. However, my local mail delivery “decided” not to inform me and not to deliver it after it had arrived. Instead, three weeks after my order, they informed me that they would send the package back to England if I did not pick it up. How very, very annoying! Anyway, when into watches there’s always something else to do meanwhile, like servicing an ORIENT movement and replacing an ETA cannon pinion with driving wheel, and…

The current amplitude is maybe not perfect (not sure what is to be expected from this calibre) but it is now in the acceptable range, especially considering it started out at 200 degrees dial up/dial down. The graph is a bit wavy and I guess the reason could be that for some reason the power isn’t perfectly and evenly transferred to the escapement. Anyway, I think I can live with that, and as I said, not sure what should be expected from this calibre. Perhaps my copy is a bit of an odd one.

My original plan was to try to locate the source of the low amplitude, but I ended up doing several adjustments before reassembling. This is what I did:

  • Adjusted the hair spring with the help of @nickelsilver's excellent illustration. Again, thank you!
  • Stripped it and ran in in my (ancient) ELMA cleaning machine.
  • Meticulously pegged every bearing and jewel hole including the barrel. Then rinsed and brushed the parts in IPA to get rid of any peg wood residue, carefully inspecting everything to be spotless.
  • Polished every single pivot.
  • Replaced the mainspring with a brand new Generale Ressorts spring.
  • Replaced the jewel for the third wheel in the main plate as it was slightly cracked. There was a super tiny groove on the pivot, but I decided to keep the wheel as this post by @rodabod made a lot of sense to me.
  • Checked and adjusted the end shake of every train wheel individually. By doing it one wheel at the time I could use my stereo microscope to actually see and not just feel the end shake. To the best of my ability I adjusted the end shake of all wheels and the pallets to about two hundredths of a millimetre. That is, barely visible even at 40X magnification. I used my jewelling tool for this operation and with this in mind for inspiration.
  • Applied Fixodrop on the pallet stones and lubricated with Dr. Tillwich 1-3. I think I’m beginning to prefer this oil over Moebius 9415. I have no evidence whatsoever that it is “better”, but it has worked well for me several times now, so I will probably stick with it

Putting an end to this chapter I’d like to thank all of you for all suggestions, help and inspiration! A special thank you to @Endeavor who kept my spirits up when I was feeling lonely and lost!


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Thanks @VWatchie; some movements are what they are. Not all of them are high flyers but can still be very good & accurate runners. Looking at the pretty constant positional amplitude and corresponding daily rate, this is one of them! There aren't many watches which receive as much TLC as this one and therefor it will serve you well ..... that's an universal thing ;):biggrin:

I commend you for your pursuant and dedication; Well Done !!   :Bravo:

 

Edited by Endeavor

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Thanks guys! Adjusting the HS, replacing the cracked jewel, and adjusting end-shake using my jewelling tool were the three major learning points for me. What caused the low amplitude is of course difficult to determine having taken so many actions at once, but I guess the combination of adjusting the HS and replacing the cracked jewel probably is what did it.

Edited by VWatchie

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