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Need help with Unitas 6325 amplitude problem


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Yes, of course......., I could have known from looking and some thinking :startle:

So, the test in the video is inconclusive.

Also, in the 2nd video you needed far too many spring-power to get the balance going. Normally, say 5-6 clicks, max 1/4 of a turn of the ratchet wheel should be enough to get the balance-wheel ticking over. That doesn't seem to be the case.

Leaves you with a systematic trouble shooting, to find out where the fault or faults is/are. There is no magic to a movement and the starting point is the main-spring. The power transfer from the main-spring to the escapement and than the escapement self.

Before you started on your watch it was running around 260 degrees horizontally, so there wasn't and couldn't have been that much wrong with it in the first place. Sometimes people get too hang-up on the amplitude alone.

My suggestion is to start from scratch again. Redo the main-spring (clean/oil). Build the bare (with nothing attached to it) power-train up (with clean pegged jewels and pegged pivots) and see how it performs; ideally you see recoil in the escape wheel. It should run smooth until the main-spring is fully unwound, no tapping required.

When you know the train is fine, you can exclude that from the "trouble"-list and focus on the next, the escapement. You know how I think about the fantastic Moebius 9415, so go initially for the Dr.Tillwich 1-3 . If you don't get a ticking balance with a few clicks of the ratchet, you have to separate and split your focus on escape-wheel/fork and fork / balance-wheel. Remember, unless you've done something to it, there wasn't much wrong with those items in the first place, so no point in bending / aligning hairsprings etc. Let's get first back to where you started.

All should be done without anything attached to the power-train. Let's get first the movement running before attaching all the horns & whistles.

 

Edited by Endeavor
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Sorry for being a bit laconic in my previous replies. I was playing table tennis and watching football (Everton - Manchester United) with my 10 year old son while thinking about my amplitude problems. Anyway, now I have a few minutes of quietude.

Having re-read the posts in this thread and your recent posts and the more I've been thinking about it, the more convinced I am that the going barrel needs to be gotten out of the movement and investigated. I'll try @nickelsilver's method as shown here.

1 hour ago, Endeavor said:

There is no magic to a movement and the starting point is the main-spring.

I just love that sentence. For someone who didn't do anything mechanical for 55 years, watch movements oftentimes still feel like an enigma to me. I know well how the various parts of a watch work and interact with one another from a theoretical point of view, but I still haven't been able to fully transform this into an abstraction where things and events feel perfectly obvious. I'm getting there though! :gym:

Yes, looking at the first video again it does seem to indicate that further investigation is required. For those having made the fundamentals of how a watch movement works into an abstraction, that's likely very obvious, but not so to me (not quite yet anyway). Anyway, now I'm thinking that if the train was perfectly free (from the barrel arbor to the escape wheel pinion) then touching the crown (which is what I'm doing first in the video after having "over unwound" the mainspring) should not make the wheels spin, but they sure do. I think I was fooled by the fact that as soon as I touch the winding crown the train starts to spin, but that indicates that there's power trapped within the mainspring barrel which is released when I tap the crown. If there was no power in the mainspring, because all of it had already been released to the train, nothing should happen when I tap the crown. Seems pretty obvious to me now!

2 hours ago, Endeavor said:

My suggestion is to start from scratch again.

I will and I want to! Thank you! And if I run into some "enigma" I'll report back and you can give me your opinion which is immensely appreciated! I will even assemble the barrel without the mainspring to make sure it has shake and spins freely. If not I'll adjust it with my staking set as described here. Yes, I got myself a staking set too. When will it ever end?! :o

Thanks, for your feedback @Endeavor I was beginning to feel very lonely here, but not so any longer! :thumbsu:

 

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"Testing if the mainspring barrel spins freely takes just a moment and rules out one of the most vexing causes of low amplitude. If you don’t do this and get a watch running at 230 degrees dial up, you’ll run around in circles trying to troubleshoot the problem. Good amplitude starts at the mainspring barrel, so scrub and spin that sucker."

From the article: Testing Barrels Before Inserting Mainsprings

Seems very much in line with your approach @Endeavor!:biggrin:

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  • 2 weeks later...

I've now taken the movement apart again and have re-cleaned it. After this I pegged the mainspring barrel holes (now perfectly clean), recleaned the barrel, inserted the arbor and closed the lid. The barrel spins mainly freely, but with some very slight resistance when I spin it the way shown by @nickelsilver in this post. As far as I can tell the end-shake of the barrel arbor is perfect, but there seems to be zero side-shake. I believe the very slight resistance felt when spinning the barrel would be eliminated if I could increase the side-shake just a tiny bit. The article I linked to in my previous post only explains how to increase arbor end-shake but not how to increase side-shake.

So, I wonder if anyone can tell me how I can increase the side-shake of the mainspring barrel arbor just that tiny bit? I have a nice staking set. Perhaps that can be used somehow to do the job?

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Hi VW   I would advocate the use of a watch broach in a pin vise to open the hole slightly. The method I would use is insert the broach attached to the pin vise and with no downward pressure on the vise/broach the weight of the vise in the vertical being enough and then retry, if not enough repeat and try again.   the idea being to remove as little as possible each time .       Cheers

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2 hours ago, VWatchie said:

I believe the very slight resistance felt when spinning the barrel would be eliminated if I could increase the side-shake just a tiny bit.

If that's really the issue, what about fitting an hole jewel where one should have been installed. If you can source a correctly sized one and have the necessary tools that seems a logical task when always aiming for the best.

Edited by jdm
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12 hours ago, VWatchie said:

So, I wonder if anyone can tell me how I can increase the side-shake of the mainspring barrel arbor just that tiny bit? I have a nice staking set. Perhaps that can be used somehow to do the job?

You have to think very, very deeply before you start doing things like that. In fine-mechanics all is done to reduce tolerances. That you can't feel it doesn't mean it isn't there. In fact, if all else stays the same, a few thousands of a millimeter play is enough; play=play.  Increasing the hole sizes, as I understood of the barrel, and the barrel will tilt (even more), meaning altering the arbor/barrel contact area which could lead to more wear or in the very worse case gouging of the materials.

Next to that, probably through the years, the current contact surfaces have worn smooth. I doubt if you can achieve the same smoothness again and if not, more friction & wear.

Edited by Endeavor
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8 hours ago, Endeavor said:

In fine-mechanics all is done to reduce tolerances. That you can't feel it doesn't mean it isn't there.

That sounds extremely insightful @Endeavor! The more I do this the more I start to realize that watch repair is an application of fine-mechanics. (I'm sure that sounds perfectly obvious to most members on this site) So, having a solid understanding of fundamental fine-mechanics is likely the very best starting point for successful watch repair.

So now that you mention it, all of what you say makes a lot of sense. In my previous post I stated that side shake between the barrel arbor and the barrel holes were zero, but now that I've read your post I realize that can't be so. If side shake was indeed zero the barrel wouldn't be able to rotate around the arbor, unless excessive force was used, and perhaps not even then.

Anyway, please have a look at the video below and let me know if you think the barrel spins freely enough around the arbor to proceed with the assembly of the movement and continue the investigation of the low amplitude.BTW, in the video I seem to confuse side shake with end shake.

I will assemble this movement in as small steps as I can and test everything separately whenever possible. I don't mind how long it takes as my goal is to learn and to find the true source of the low amplitude. The next step will of course be to ensure that the barrel spins freely between the mainplate and the barrel bridge. Here too, tolerances should of course be very small as the mainspring otherwise would tilt the barrel causing friction and wear.

 

Edited by VWatchie
clarification
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2 hours ago, VWatchie said:

"I'm sure that sounds perfectly obvious to most members on this site"

Sometimes one wonders as some seem to gladly assist you in digging your own grave ..... but that's another matter ;)

I'm not sure if this "free-moving-barrel-test" will prove anything ...... :unsure:

In the video it's also unclear to me whether there is a spring in the barrel or are we looking an empty barrel just rotating around the arbor?

 

 

Edited by Endeavor
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Yes, of course, I should have mentioned it, the spring is not in the barrel as it would make it impossible to see how well the barrel spins around the arbor which is fixed between the tweezers.

So, my idea was that if someone seeing my video has enough experience of how a perfectly working barrel and arbor would look and feel like without the mainspring in the barrel, hopefully he or she would be able to tell me if it looks OK or if some additional action possibly needs to be taken.

In this post, @nickelsilver says: "Ideally it should move with a blower but just moving it by hand will tell you if it's free". Well, as can possibly and hopefully be seen in my video I have to go pretty hard on the blower to make the barrel move. It spins when I push it lightly with the piece of peg wood, yes, but the question is; it good enough not to impair amplitude!? :unsure:

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No, I don't have experience enough to say whether a barrel should spin freely around the arbor when just puffing some air. In the end of the day it's of course a friction-bearing and even a very bad one too; metal-to-metal. Next to that, even if it would rotate freely (as it also may do when there is too much play), it's hard to tell how the bearing would behave under load, i.e. with a spring under tension in the barrel.

Given the fact that it is a (used) friction bearing, to stay within reason all you can do, IMHO, is to ensure that there is enough play such that the arbor can rotate (which it seems to have), that the bearing surfaces are as clean & smooth as possible (you pegged the heck out of them) and to ensure proper lubrication to reduce friction between the bearing surfaces.

With to stay within reason I mean to see how far you get working with the materials you currently have and the way the watch was designed.

Next is of course to ensure, or try to achieve a as smooth as possible power release by the main-spring.

Since it is an old movement, again to stay within reason, there are many things over which you have no control or can't alter. You can work your way from the arbor down to the escapement and do your best in checks, cleaning and lubrication. Than the escapement itself which is (at least to me) a complicated matter and lots can go/be wrong or misaligned (even ever so slightly) reducing the amplitude. It takes a very deep understanding on how the escapement exactly works, interconnects and should be aligned; something which I try to grasp (too?).

Once you get down to that, it would get very interesting & educational if a forum member has that deep understanding and is willing to spend the time & energy to guide not only you, but hopefully lots of others here, through that process. Only than we will find out whether something can be / could be done to increase the amplitude ..... (?)

I follow with interest your proceedings / progress ;)

 

 

 

 

 

 

 

 

 

 

Edited by Endeavor
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Thanks, Endeavor, lots of food for thought in your post!

14 hours ago, Endeavor said:

even if it would rotate freely (as it also may do when there is too much play), it's hard to tell how the bearing would behave under load, i.e. with a spring under tension in the barrel.

I can well imagine a barrel with a little too much play binding up under tension from the mainspring, possibly making things even worse than a barrel with a tad too little play. There’s of course a sweet spot that would be difficult to determine precisely.

In my mind, ideally no shake should be felt (between the arbor and the barrel) yet the barrel should spin “freely”. “Freely” is a pretty floating concept though, and that is the crux of my concern; is it free enough not to impair amplitude in any significant way!?

In parallel with this Unitas movement I’m servicing an Orient movement (my first Japanese movement) and I did the same experiment with its barrel and arbor which can be seen in the below video (just 1 min 27 sec. long). In this case everything feels just perfect. The friction feels minimal and a light puff with the blower makes the barrel spin.

I’m contemplating polishing the contact surfaces using diamond paste to see if it would make any difference. Of course, I would have to be very careful not to remove too much material (I guess, as I have no prior experience with diamond paste). What do you think? Worth a try?

 

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Those sweet spot diameters and tolerances have been determined by the movement designers. Hard to find out unless you get hold of the design blue-prints.

Since you are in the experimental phase anyhow, you could try with very fine diamond paste #6000 or higher ( #10.000 grit). Problem with diamond paste is that you have to clean it very thoroughly as you don't want to leave fine diamond dust behind which will keep on grinding = wear & friction.

It is hard to judge from a distance, not feeling how things feel, to say whether you are on the right path. Regardless, lessons can always be learned and experiences gained ........ that's were the do's and the don'ts come from :)

 

 

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32 minutes ago, Endeavor said:

Those sweet spot diameters and tolerances have been determined by the movement designers. Hard to find out unless you get hold of the design blue-prints.

I'd say chances are pretty slim... :lol:

33 minutes ago, Endeavor said:

Since you are in the experimental phase anyhow, you could try with very fine diamond paste #6000 or higher ( #10.000 grit). Problem with diamond paste is that you have to clean it very thoroughly as you don't want to leave fine diamond dust behind which will keep on grinding = wear & friction.

It's great to be a hobbyist in this context as I can spend any time on any kind of "trivial problem" to learn more about it. I'll do the diamond paste polishing and see where it leads and thanks for the tip as I had no idea about what grit to start with. And yes, I'll make sure to clean thoroughly!

39 minutes ago, Endeavor said:

t is hard to judge from a distance, not feeling how things feel, to say whether you are on the right path. Regardless, lessons can always be learned and experiences gained ........ that's were the do's and the don'ts come from :)

I'll make sure to report any thing I learn back! Thanks a ton for your support! :thumbsu:

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  • 2 weeks later...

Just a quick update and a new observation that I believe could have an impact on the amplitude?

So, the discussion continued here and instead of ordering diamond paste I've ordered some smoothing broaches. I'm still waiting for them but I'll report back to anyone interested once I've given it a try.

The new observation that I've made is that the jewel for the third wheel in the main plate is cracked. At 40X magnification I really can't see if the crack reaches all the the way out to the inner rim of the jewel hole, but I can't rule it out. Now as I remember it from watchrepairlessons.com, any cracked jewel should be replaced so that's what I'll do next. I have carefully recorded at what depth it sits in the main plate, I have removed the jewel, measured it (1.00 mm) and have measured the pivot in my Seitz jewel gauge. So, two questions;

1) What is the impact of a cracked jewel? Could it create drag and enough to degrade amplitude? Mind you, in this case it is not clear whether the crack goes all the way to the jewel hole.

2) When measuring the pivot it sits perfectly in the 0.17 mm jewel. As a matter of fact I can't feel/detect any side shake at all, but it seems to spin freely in the hole. So, should I go for 0.17, or 0.18, or possibly 0.19? Is there a best practice?'

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2 hours ago, VWatchie said:

1) What is the impact of a cracked jewel? Could it create drag and enough to degrade amplitude? Mind you, in this case it is not clear whether the crack goes all the way to the jewel hole.

Cracked jewel - if it reaches the inner edge will score the pivot and introduce friction. This is a modern movement built to tight tolerances and from the sounds of things, minimal sideshakes - get the same jewel as a replacement.

Finally, listen to Nickelsilver. The most likely cause for issues is at the lower torque end of the movement, ie. the faster end, ie. towards the escapement. Mainspring barrels do not have to have so little friction that they can spin under their own momentum. They have greater side-thrust and hence have thicker, stronger pivots with more friction. But that matters less as there is more torque and less velocity.....

One thing which I didn't see mentioned - did you check that your hairspring is not just "flat in the round" but also flat in general? When it breathes, you should not see any rippling up and downwards, and obviously no coils should ever touch. Sorry if that's obvious, but it's a very common issue on watches which have been mishandled. A hint can sometimes be that the balance oscillates faster than expected, especially in particular positions. The balance clearly swings freely which you demonstrated.

You can experiment with adding friction at the different wheels - stick a fine oiler in the escape wheel oil sink and push against the pivot. You may be able to stop the movement entirely. Try the barrel.... see much difference? Probably not.

When you observe the action of the escapement, check that with a few winds of the crown that the pallets are consistently getting the same amount of draw when they lock. If they don't draw inwards properly then it's most likely lack of torque getting through the train (friction?) or the sides of the pallet stones or escape teeth are not clean enough. You will sometimes need to inspect the stones and peg them or dip into pith wood to clean the sides. 

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14 hours ago, Marc said:

General rule of thumb is that the hole should be big enough for the staff to sit at an angle of about 5 degrees from vertical. 

 

12 hours ago, rodabod said:

get the same jewel as a replacement.

Didn't think of it, but what I can and will do is place the pivot in the original jewel (mounted in the main plate) to see what it feels like. That should give me a good indication of which is the correct hole diameter when compared to the jewels in the jewel gauge.

 

12 hours ago, rodabod said:

Cracked jewel - if it reaches the inner edge will score the pivot and introduce friction.

OK, so that is what a crack causes. Good to know. I'll take a close look at the pivot in my stereo microscope (40X) and see if I can see any damage done to it.

 

12 hours ago, rodabod said:

The most likely cause for issues is at the lower torque end of the movement, ie. the faster end, ie. towards the escapement.

I believe there's an absolute consensus around this and it is what @Mark teaches (fault finding course) at watchrepairlessons.com. However, @Endeavor pointed out that in one of the videos I've published it looks like there could be a friction problem in the train and as I had been so focuses on the escapement I had completely forgotten about the train and the mainspring barrel. As someone wrote "Good amplitude starts at the mainspring barrel, so scrub and spin that sucker.", and now that I found a cracked jewel I had all the more reason to start my investigation with the train rather than the escapement. So, I hope that explains what could appear as having the wrong focus.

13 hours ago, rodabod said:

One thing which I didn't see mentioned - did you check that your hairspring is not just "flat in the round" but also flat in general?

No I didn't so I'll will take a very close look at this too.

 

13 hours ago, rodabod said:

When you observe the action of the escapement, check that with a few winds of the crown that the pallets are consistently getting the same amount of draw when they lock. If they don't draw inwards properly

Not perfectly sure what this would look like, but I guess having a look at several movements using this method over time should at some point make it clear to me what it is right and what is wrong. Any illustrations or more detailed explanations out there?

Finally, thanks for your very informative post, much appreciated! :thumbsu:

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The third wheel pivot is definitely scored. Not much, yet visible in my stereo microscope (40X). The width of the score is extremely small, considerably less than a one hundredth of a millimeter, but still I guess it will need to be replaced? Perhaps this and the cracked jewel is what has been deducting the missing 20-30 degrees of amplitude?

So, when I test the pivot in the original jewel hole in the main plate and compare it to the jewels holes on my jewel gauge, .18 mm feels slightly too narrow and .19 mm slightly too wide. I guess both would be fine, but we want tight tolerances right, so I guess I should go with .18? Mind you, the pivot fits in the .17 mm hole as well, but then there's basically zero side shake.

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Polish the pivot to smooth out the scoring. It should be ok once sat in a smooth jewel. I'd just go with whatever pivot hole size was originally spec'ed. Unless of course you reduce the pivot width significantly, which I doubt you will.

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