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Hello All 😃

It's now for the 3rd time that I'm working on a 1975 Omega Speedmaster Mark II with a 861 movement. The watch, which was never truly loved, used to belong to a family member. Upon my first reception it was in a pretty beaten-up state;

SMM-2-1.jpg.99d440fc0e22693a3b226787b76274ab.jpg

My first service (2017) can be seen here: https://www.watchrepairtalk.com/topic/6842-omega-861-speedmaster-mark-ii/

Even though during the service the mainspring was changed out for an original Omega mainspring, the "after winding" amplitude (as can been seen in the walkthrough) wasn't that great. The watch went back to its owner and was shelved from 2017 until 2022, when the watch became my property.

Now I've stripped the movement twice, cleaned, pegged the jewels, pegged the Chatons & pegged the pivots, manipulated hairspring until it ran 100% horizontal and concentric, oiled to the best of my abilities, but the amplitude stays relative "low". It has still the same "new" mainspring installed in 2017, but cleaned and oiled it again. The escape-wheel shows a recoil (obviously without pallet fork). I tried different lubricants on the pallet-fork jewels, now running on Moebius 9415, but there are no significant differences.

Omega doesn't care so much about the amplitude directly after a full wound, but rather the amplitude after 24 hrs of running. According to Omega, for a 861, the minimum crown-down amplitude after 24hrs should be no less than 190 degrees.

70583624_ScreenShot2022-07-30at13_13_16.png.b5a9623708764af388ae4b425904e936.png

Clearly, I don't get that 🤨

Also, in the horizontal plain, the amplitudes aren't equal (more pronounced after a full wind).
My suspicion is that the problem lays in the balance-staff pivots  (47 years old movement), but not having enough magnification, I can't proof. End-shake doesn't seem excessive, minor to none balance side-shake. A new balance-staff is expensive and I don't have the tools, neither the experience to do a balance staff change-out. A complete new balance assembly is (for me) prohibitive expensive (over €400).

The watch won't be worn daily so, unless members have some idea's where to look, what can be tried next or can help me out ?, I was thinking of installing a slightly stronger main-spring. The original spring (1.30x0.115x420x10.5) has a thickness of 0.115mm and the next up CousinsUK has in stock is 1.3x0.123x440x10.5 with a strength of 0.123mm. Obviously this will put more strain / force on the power-train, but as said the watch will only be worn occasionally and a stronger spring will (hopefully) assure full functionality of the chronograph.

Looking forward to your thoughts / suggestions ! 😉

Here below are the results after 24hrs;

Dial UP (24hrs);

IMG_1925.thumb.JPG.4b355f862e2b6e13725e897c8dab6fb7.JPG

Dial DOWN (24hrs);

IMG_1926.thumb.JPG.b2fa17d162e33b6d769eea35e926f626.JPG

Crown-DOWN (24hrs);

IMG_1927.thumb.JPG.84371cd213a6eb6c6df0d27ffbdfe5ea.JPG

Crown UP (24hrs);

IMG_1929.thumb.JPG.176bf012c7fec57622a7f1b4770d94f8.JPG

Crown LEFT (24hrs);

IMG_1928.thumb.JPG.5dfaaa7620bd0d407f114ec32e02ed01.JPG

Crown RIGHT (24hrs);

IMG_1930.thumb.JPG.27599e76bca0f216f54dc48c0cbc1129.JPG

 

 

Edited by Endeavor
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What's the horizontal amplitude at full wind (minus a few clicks)? It's not uncommon on these to find that the cap jewels have become pitted, which also damages the pivot end. Sometimes you have to turn the jewel just so to see the divot. But your amplitudes in vertical compared to horizontal at 24h look normal, though all are quite low.

 

I see these (and 321) quite regularly. If everything looks right and I'm still getting low amplitude, like 260 at full wind, I tend to have a look at the escapement. A very small adjustment, like 0.005mm, can help a lot. Another common issue on the 861 is worn holes in the bridge and less commonly the mainplate for the barrel. That can rob a lot of power. The solution is bushing the hole/s. You have to check carefully, as the arbor pivot only goes part way through the hole in the bridge- it can look fine from the top but still be very worn. If you google "Archer 861 barrel bushing" you'll see some good info on that from a professional who does a lot of Omega (don't want to link to other forums).

 

A quick thing you can check, which has caught me a few times and I don't have a good explanation for, is residue in the fork slot. Every now and then I got a problem piece in that had everything perfect, and checking that under the microscope showed a white deposit where the roller jewel contact. Removing it with pegwood solved the amplitude issue.

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Thank you for your suggestions 😉 Funny thing is that the amplitude doesn't increase a lot when fully wound, it seems that the amplitude is a fairly "straight" line down from low to lower.

Beat-error slightly adjusted compared to previous pictures.

Dial UP, fully wound;

IMG_1932.thumb.JPG.ea11fcb7dce3054bdc16accf493e4956.JPG

Dial Down fully wound;

IMG_1931.thumb.JPG.8303a1c6533db015983a8cd14d68f2fa.JPG

What do you mean with "a very small adjustment, like 0.005mm"? Escape wheel / fork or balance UP/down?

"Another common issue on the 861 is worn holes in the bridge and less commonly the mainplate for the barrel"; I'll take it that it's the hour recorder bridge 1775, housing the "top" of the arbor. I'll check the arbor play !

I will check the fork slot and check the "Archer 861 barrel bushing", thanks for the tips !

The cap-jewels looked nice flush with no pitting.

I will report back as soon as I worked through your info 🙂, Thanks .....

 

Edited by Endeavor
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16 minutes ago, Endeavor said:

 

 

What do you mean with "a very small adjustment, like 0.005mm"? Escape wheel / fork or balance UP/down?

 

 

That would mean, if the adjustment is there, move a/the stone/s in that amount, or, if closing the banking/s- it depends on what the situation is in the escapement.

 

But yes, that amplitude is too low. I'm betting on it needing bushings now.

 

I just did a 321 this week, lots of abuse it's seen in the past, but with the original mainspring it hits 270 and drops to 250 at 24h. Didn't need bushings or escapement work, but had a pitted jewel, worn pivot end, other pivot bent, hairspring all out of true. They can be a lot of work but they really run great if all's in order.

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Yes, you make me excited again, that there is "hope"  ! 🙂

It's a 1/2 heirloom, a wedding gift in 1975 but the partner has sadly passed. So, I've to judge how much to invest and/or (more importantly) if I can do it?

Interesting point; initially I forgot about the bridge (1775), but the readings after installment didn't change a lot 😲 So you may have a good point !

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I had a low amplitude with a completely serviced Citizen. After having red this this article I found the total lock significantly unequal on the entry stone and exit stone. After slightly correcting the appropriate banking pin the watch gained about 20° of amplitude. So - as @nicklesilver said - you should carefully inspect the escapement.

Edited by Kalanag
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A bit of a long shot - but it happened to me : I have a simple manual wind Smiths cal 0104 where, after cleaning (including fitting a new mainspring) I couldn't get reasonable amplitude.

I stripped/cleaned/examined time after time with no effect. Everything looked good. In desperation I took out the "new" mainspring, and found it wasn't springy at all. You could bend it it to any shape !

I might have just been unlucky and this might be a very rare occurrence?  (I bought it from the "big" UK parts supplier). 

Have you come across many new defective mainsprings @nickelsilver ?

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58 minutes ago, Kalanag said:

After slightly correcting the appropriate banking pin the watch gained about 20° of amplitude.

The pallets were hitting the banking pin and you opened it up? If so, was there a sound indicating the contact? Most modern and contemporary mov.ts have banking limitation embedded in the mainplate hence not adjustable. I'm a bit surprised this Citizen has pins.

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3 hours ago, jdm said:

The pallets were hitting the banking pin and you opened it up? If so, was there a sound indicating the contact? Most modern and contemporary mov.ts have banking limitation embedded in the mainplate hence not adjustable. I'm a bit surprised this Citizen has pins.

I had to slightly bend one of the pins inwards to limit the moving angle of the pallet fork and reduce the lock. Here is a Citizen 6900 plate with the banking pins circled in red:

E8CD6D6B-E8C3-4655-A49E-73957A9796C9.jpeg

Edited by Kalanag
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13 hours ago, nickelsilver said:

I see these (and 321) quite regularly. If everything looks right and I'm still getting low amplitude, like 260 at full wind, I tend to have a look at the escapement. A very small adjustment, like 0.005mm, can help a lot.

What I find interesting is you talk to people who work for a Swatch group service center for instance the way they deal with this is they just replace the escapement components. It's standard practice anything looking like what you're seeing They are replaced.. Of course they have a back room of infinite quantity of parts so they can do that.

Same as people I know that work on Rolex watches anything resembling a timing issue of any kind whatsoever they replace the balance staff. Basically everything has to be perfect if you want perfect timekeeping.

Also attached an image of timing specifications from Omega for this watch

 

 

5 hours ago, Kalanag said:

had to slightly bend one of the pins inwards to limit the moving angle of the pallet fork and reduce the lock. Here is a Citizen 6900 plate with the banking pins circled in red:

So do you think some previous repair person bent the banking pin? Plus is there any consequences to doing this?

 

12 hours ago, nickelsilver said:

That would mean, if the adjustment is there, move a/the stone/s in that amount, or, if closing the banking/s- it depends on what the situation is in the escapement.

Theoretically and watch repair you're supposed to be doing a escapement check to verify all the safety features are functioning and that pallet stones are where there supposed to be. Just in case somebody's played with this before you.

13 hours ago, nickelsilver said:

What's the horizontal amplitude at full wind (minus a few clicks)? It's not uncommon on these to find that the cap jewels have become pitted, which also damages the pivot end. Sometimes you have to turn the jewel just so to see the divot. But your amplitudes in vertical compared to horizontal at 24h look normal, though all are quite low.

I don't suppose that the hole jewels wear out or get damaged with time?

 

Omega 861 timing specifications.JPG

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2 hours ago, JohnR725 said:

So do you think some previous repair person bent the banking pin? Plus is there any consequences to doing this?

It‘s more than unlikely that a previous person had bent the pin. I assume there are high factory tolerances either at the pin position or the pallets. Because it’s beyond my skills to precisely move the pallet of a tiny ladies watch bending the pin was the only option and a shoot in the dark. I did know that doing this would influence some vital clearances on the fork side. I was lucky.

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Back to the topic of this thread; I managed to take some interesting pictures and may have already discovered a, or some problems.

First up is the entry pallet-fork jewel, the draw seems to be much deeper (too deep?) than the exit jewel;

Entry jewel;

S20220731_003.jpg.ade265f060f642081ff87f562078c262.jpg

Exit jewel;

S20220731_002.jpg.5fdc60016690464a9ad2999138322813.jpg

Looking at back of the pallet fork I don't get the impression that somebody has been tempering with the shellac, unless it was done very professionally;

S20220731_005.jpg.d4cda669bc3432282e15a0dd97adaf01.jpg

S20220731_006.jpg.aba9c7a8030f7777f58771bfbf655348.jpg

The jewels appear to sit solid in the fork and if nobody has ever been tempering with the setting depth, one would assume that the jewel setting depth is "off-factory". One reason I didn't look here before is that I assumed that Omega would have done a precise job.

Next up bridge 1775 which holds one end of the arbor;

Inside;

S20220731_007.jpg.847e1333bdba4765c9179c0ea278e9fe.jpg

Outside;

S20220731_008.jpg.a2bdd8f468fc277347cb6d0bcc0934ee.jpg

I my opinion not much wear to be seen.

Slightly different this may be the case with the Barrel and train wheel bridge (1002). On the inside there is some shiny surface-wear but that sits within the diameter of the ratchet wheel, so I assume it's from the ratchet wheel but it maybe a tell-tail that the barrel is slightly tilted ?

S20220731_009.jpg.abbd7865d936dbae94d6a7678440d11e.jpg

In the centerhole hole, in which the arbor turns, one can see (under the right light conditions) a small groove. It doesn't seem very severe, but it may add to the trouble ... ?

S20220731_010.jpg.936b13e83ec2a11371f0f6b7b464fa16.jpg

@nickelsilveris this the "common" wear you were talking about?

So potentially already two problems; the pallet-fork entry jewel and perhaps the wear of the arbor-hole in bridge 1002.

Once I made myself a pallet warmer, but never work with it and have no experience with the adjusting jewels. Would it be wise to have my first "go" on a 861 fork ??

Next, if the wear in bridge 1002 is severe enough, what to do about it? I do have a full set jeweling tool (including the set of standard reamers), but also here not done often.

What's wisdom ??

 

 

 

 

Edited by Endeavor
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The entry lock does look quite strong. From the pic the exit stone looks a little light too, but could be just fine. The thing is with the escapement you have to check everything- total lock is just one aspect.

 

Briefly, to check (mind you in school some weeks are spent on this):

All checks done with balance in, some power on train

  • rotate balance slowly and observe drop lock, it should be minimal and equal on both sides
  • at the moment of drop, manipulate the fork to check for freedom, this is "corner clearance". There should be freedom, and the escapement shouldn't unlock
  • move the balance further a few degrees, check the fork freedom again, this is horn clearance to roller jewel face, should be small enough the escapement doesn't unlock
  • continue moving the balance, now you will be checking guard pin clearance. Should be smaller than the horn clearance, and if so it will also be safe

 

The above checks are checking the function of the pallet jewels relative to the roller jewel and safety roller. Observe how much lock is left with the fork horn against roller jewel- this is an indicator of how much adjustment you have as far as moving the stones in. The lock must remain safe with horn in contact with the roller jewel. All checks done on both stones of course, and in theory over the course of a whole escape wheel revolution.

 

Next,

  •  moving balance slowly, at the moment of drop lock, observe the travel of the fork to its banking (looking at the escape tooth/pallet stone, not the banking). This is the "run to the banking". It is essential, but can be very small, bearing in mind that there are sideshakes that can eat up some of the clearance between fork and roller table in vertical positions.  Run to the banking plus drop lock = total lock.

 

So to boil it down as simply as possible for practical use, you can check the fork horn clearance, observe the lock remaining, and that amount "minus a little" is about the max you can move the stone in. ***

 

If the total lock is large, and there is a lot of run to the banking, you can also close the banking. Easier said than done on many movements, as this might entail forging the banking with a punch in numerous cases.

 

***One very important thing to keep in mind with drop lock: moving one stone affects the drop lock for both itself and the other stone. If you move the entry stone into the fork, you reduce drop lock on the entry stone, but the escape tooth will also be released sooner on that stone, reducing the drop lock on the exit stone as well. And vice versa. After moving a stone, you must recheck for safe drop lock and safe fork horn clearance.

 

  • Moving a stone affects drop lock similarly on both stones, and total lock on that stone.
  • Moving a banking affects total lock for that stone, and run to the banking for that stone. No effect on the other stone.

 

 

Can't really see much regarding the barrel holes in the bridges, but that could be some wear there in the upper one.

Edited by nickelsilver
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Lots of very interesting information to digest 🤯 Daunting, but very interesting !

The good thing with this Omega is that I'm in no hurry and each time I discover that there is so much more to learn ....... comes back to my slogan on the bottom of each of my post: “The more I read & learn, the more I realize how little I know. And even what I think I know, I start to doubt" !

Thank you very much indeed !! 👍

Edited by Endeavor
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5 hours ago, Endeavor said:

…First up is the entry pallet-fork jewel, the draw seems to be much deeper (too deep?) than the exit jewel…

That was exactly my observation with the Citizen movement. Assuming that the pallet fork is better controlled than the banking pins during the manufacturing process I corrected the pin.

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Troubleshooting by elimination;

Thinking out load and even if it was for my own sake, I like to have the items I've checked documented. Also documenting my thoughts enables others to look over my shoulders to see if or where I perhaps go wrong. Next, a bonus would be if this way of troubleshooting has some educational value?

The imput so far has been phenominal and I'm slowly (trying to) work down the list of "items to check" Nickelsilver and JohnR725 have given me.

By the Omega 861 the banking is an integral part of the pallet-bridge (1005). First check is to see if in the past somebody has altered the banking. From what I can determine is that there are no signs that this has happened.

S20220801_001.jpg.2339a979bacb992793ee200dbafe0fe3.jpg

Here the banking-surfaces, both look fine and don't have any specific marks apart from a slight shiny spot on either side where the pallet-fork is resting.

S20220801_002.jpg.5bce42a7e36ba6a87bf312d995037284.jpg

With some tension on the mainspring, the pallet-fork does rest firmly against either banking sides.

S20220801_003.jpg.427be7a390ef38f2a844c7fea0ca9b12.jpg

S20220801_004.jpg.3cab898257100bc722f6cda1c7f2d9b4.jpg

 

Referring to a document of the The Chicago School of Watchmaking ( Working Swiss Escapement.pdf) I've made some assumptions;

1) I do assume that Omega placed (designed) the center of the balance anti-shock, the pallet-fork jewel and the escape-wheel jewel in one fixed "center-line".

1442773525_ScreenShot2022-08-01at13_40_37.png.ea1d1d535a0045bd70bf85a67d52b187.png

2) I also do assume that either banking, since being an integral part of the pallet-bridge and the banking surfaces being untouched, are situated 100% at the same distance from the center-line. This would implicate, with the pallet-fork looking in perfect shape, that the pallet fork, looking from the center-line, swings exactly the same amount to the left as to the right.

3) Assuming that the fork travels as much to the left as to the right, I therefor also do assume that the total travel (up & down) of both pallet-jewels are the same (?).

If all the above assumptions are correct, in my mind both pallet jewels (if correctly placed) should have the same locking-depth measured from the top of the relevant escape-wheel teeth (?) This is clearly not the case with this movement, the pallet entry jewel sits (much) deeper than the exit-jewel.

4) Assuming that Omega made 100% sure that all parts fulfill the required dimensions, with the pallet-fork horns & the banking surfaces looking normal and the fork banking out fully agaist the banking surfaces, with the roller-table rotating around the center-line the roller-jewel should enter the horns under the (clockwise and anti-clockwise) exact the same angle and hit the respective horns at the same respective CW / ACW center-line angle. (I checked that the roller-jewel sits firmly in the table).

With, as far as I can judge, the banking, horns & table-jewels checking out fine I make the assumption that (apart from the guard-pin which I haven't figured out how to check) the interaction of the roller-table jewel and the pallet-fork horns is as it should be or at least as "designed" (?)

As for what I perceive the "corner clearance" (?), I managed to take some pictures (with some slight tension on the main-spring) showing the fork-angle and fork-distance from the banking surface just before the unlock.

Here just before the unlock of the entry-jewel, the guard-pin already getting close to the center-line.

S20220801_007.jpg.b64fd76582213d434dca7eeeac0914a9.jpg

Next picture just before the unlock of the exit-jewel. Clearly the distance from the fork to the banking is less than the distance of the fork to the banking just before the unlocking of the entry jewel. With everything else checking out so far, this shouldn't come as a surprise (?)

S20220801_008.jpg.23aaa0eb1fddf27f47aaf242180306ae.jpg

I still have to get my head around the fact that if one jewel-depth gets changed, it effects the other ...... but that's the next step 😉

Any comments so far .......

Hope to hear ...... !!

Oh, a picture of the roller-jewel .... seems fine to me (?)

S20220801_005.jpg.98ac978e9eddb42217cce3caa8d59b05.jpg

 

 

 

 

 

 

 

 

 

Edited by Endeavor
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Yes, that was one of the things JohnR725 also mentioned and it was on my list to check today. The pictures are taken by an el-cheapo electronic microscope with, obviously, cheap lenses.

Judging by eye, looking over the pallet-pivot, the guard rivet and the tip of the guard, it seems pretty in center of the horns. I tried to make some pictures with the microscope but when slightly off center one gets already a parallax "fault". 

S20220802_003.jpg.144cf7eb43df7a498b04f27c97d91039.jpg

S20220802_005.jpg.56bf46886a5101527184887c29ba4aeb.jpg

 

It's hard to say, perhaps very slightly to the right ??

S20220802_003.jpg.6e0b9eb20315cc14ae94560a7b797b76.jpg

Edited by Endeavor
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53 minutes ago, praezis said:

Maybe a deceiving photo, but the rim is crumpled and the jewel surface looks like curved (wrong side?).

I'll check both, but putting the cap-jewel upside down in the Chaton THAT would be something......... but you never know ! 😉

EDIT: cap-jewel fine. One could argue that the rim is a bit rough. Knowing in great lines the history of this watch since 1975, the rim (like with the entry-jewel) must have been like this since the watch left the Omega factory. Not to say that this is as it supposed to be, but I've to be very sure what I'm doing before I make any changes to what passed the 1975 Omega quality control.

Edited by Endeavor
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