So I have been looking into the new 3861 movement and have some initial thoughts...

The movement has generally been thought of as an 861/1861 with a co-axial escapement, but that isn’t the case at all. There are very few parts in the 3861 that originate from the 321/861/1861 calibers, and most of the parts are specific to the 3861. Even parts that visually appear the same as the 1861, are specific to this caliber. In some cases these may be finishing differences, but I can’t say for sure just looking at the list.

There are some specific design changes that have been made, and the most obvious one is the co-axial escapement – the co-axial wheel and pallet fork are from the Cal. 8800. Of course the movement now uses a silicon balance spring and a new balance that is free sprung, rather than using a regulator (the balance assembly is specific to the 3861). But there are also changes made for the hacking mechanism, and a few other things. The dial side has a different look than the previous designs due to an oversized spacer called the dial support, and the new design covers a much larger area than it does on any of the previous movements, and also includes a section that restrains the hour wheel (this used to be held by the dial itself along with a dial washer).

There is a big positive that I see in that both ends of the barrel arbor are now supported by jewels. Previously the barrel arbor just ran in a hole that was drilled directly into the brass “barrel and wheel train bridge”, and in a similar hole in the “hour recorder bridge”. This leads to wear and elongation of the hole over time, and when it gets bad enough it will allow tipping of the barrel inside the movement and loss of power. This often required the parts to be replaced (what Omega does at service) or for the holes to be repaired using bushings. In fact bushing the hole in the barrel and wheel train bridge is the most common repair I do on these watches, and I even see 1861’s with wear that requires repair, so it’s not just the really old watches that suffer from this. Here is an example of the wear often seen in the 861/1861 bridge:



And after being repaired with a bushing:



So this accounts for of a couple of the jewels that raise the jewel count from the 18 found in the 1861, to the 26 jewels in the 3861. There are 2 more added for the co-axial wheel, and then 2 more on the pallet fork. All these serve a specific purpose that makes sense from a watchmaking point of view, but that leaves us 2 jewels short of the 26. So where are those?

The last two are very puzzling to me, and they are added for the minute counting intermediate wheel – one on the “barrel and wheel train bridge” and one on the “chronograph bridge” and these were formerly just bushings. When the chronograph is running, the wheel that the seconds recording hand is on turns once per minute, and it has a small finger on it that flips the minute counting intermediate wheel, and that wheel in turn flips the minute counting wheel that the hand for that is attached to (located at 9 o’clock sub-dial).

Here is where the bushing is in the barrel and wheel train bridge:



And here is where it is in the chronograph bridge:



So why would Omega add jewels to a wheel that only turns when the chronograph is running, and only turns 18 degrees (1/20th of a rotation) every minute? Well it’s certainly not because of wear, because in servicing hundreds of Speedmasters I’ve never had to replace the bushings that are in these locations because they were worn out (have replaced some because of damage due to ham fisted watchmakers). So that one is a mystery to me...

I had mentioned in one of the threads on the 50th watch that the sub-dial hands are all the same hand. This is very different from the traditional Speedmaster movements where all the sub-dial hands are different, because the posts they mount to are all different sizes as you can see here:



In the previous versions, the hour recorder post was the largest diameter, the minute counter a bit smaller, and the constant seconds the smallest. These are all now one size.

One other thing of note is that the movement is shown in two finishes – one in Moonshine gold, and the other is what they are calling a “standard” finish, and that is rhodium plated and resembles the 1863. Normally when the finish changes Omega would give the movement a new designation (there are some exceptions) but in this case they are still both called the 3861. I think the fact this is in a “standard” finish indicates this will likely be the caliber used in Speedmasters in the future.

So as often happens when movements are initially released, the makers find that changes need to be made, and the 3861 already has had some changes made to it that are found in another document. These are so far minor issues related to parts sometimes rubbing on each other that shouldn’t, so the upgraded parts are not considered mandatory replacements.

For anyone who has one of the watches that house this movement, and didn’t immediately flip it for a profit, I would be interested in hearing how the watch is performing so far.

Cheers, Al

 

Great post Al

 

Thanks for the initial analysis ...

 

Amazing!!!! Thank you @Archer as always for sharing your technical explanations and other thoughts!!!

 

Thanks for the amazing pictures to follow as well!

 

Very informative as always, Al. While your post, I will say extremely well-written and concise, is a very technical aspect of the new movement, what is your opinion on how it will perform in the long run? See any issues that come to mind?

Also, in terms of servicing, does it seem more difficult?

 

Interesting that this problem , which is obviously not unique to the watches you service, has been known by the company for half a century, yet it took a completely new caliber to appropriately address the specific issue.

 

Great article...look forward to reading about the first service job on one of them

I have heard/read that this one is designated the '3861M' (one from Fratello, but before hearing that, I do recall that I had heard that before...cant remember where)...maybe the extranet is not as fast to update...

 

The 3861 is "one" movement, and the full movement designation is:

6003861A10000106

The parts of the movement change from the standard version to make it the Moonshine version simply have a letter "O" suffix added to the end of the part number, so for example the chronograph bridge is part #7223861A15040 for the standard version, and part #7223861A15040O for the Moonshine gold version.

There is zero evidence to suggest that one or the other will be called "3861M" in any official Omega documentation. I'm going to suggest it's not the Extranet that is misleading here.

Cheers, Al

 

Omega would likely argue that if people had their watches serviced in the recommended time frame, this wear would not be an issue.

By the way there are hundreds of other movements out there that are like this also...

 

Since I asked specifically for feedback on performance, that should tell you the answer there.

I haven't handled one, so I have no idea how these actually run. No performance data is included in any documentation that I can find so far.

As for how I think it will perform in the long run, my feelings on co-axial movements are pretty well known I think.

The layout of the movement is very much the same, and the differences I've outlined won't make it any more difficult to service really. Of course other than the additional oiling that will be required on the escapement because it's co-axial...

 

And would you agree with this, or do you believe it's a design flaw?

 

Yes, and yes.

 

Awesome post - cool to see a detailed comparison between the 3861 v.s. 1861/861. I'd also be interested to hear how these are performing under daily wear.

 

I've got the two-tone 50th, over the week it's kept time but then so do my two other new Speedmasters (Speedy Tuesday & Ultraman) and they aren't chronometer-rated. Will keep an eye on it of course.

One Q - is the movement in this model Moonshine gold? I thought that was only for the full-gold 50th model, no?

 

I am certain you will update this thread when whatever it is appears

 

There's an old trope that ... well, I can't remember the first time it was trotted out to me but I can guarantee it was an old watch maker or older collector ... that goes something like "15 jewels is enough and anything else is just bragging". Do you think the last two jewels were added just to one-up the competition? If I recall correctly, the Daytona currently has 44; I know I've got something in my collection with 41 ... can't remember what it is. Perhaps Omega simply want to restart the jewel-count race?

 

Yes, in the unlikely event that actually happens.

 

Brilliant post thanks !

Performance wise. I’ve worn mine for 2 weeks solid and in that time it has gained just 1.5sec

It only gained early on, maybe around day 3 - 5. And since it has ran absolutely flat

It has been put through all sorts of use apart from shock impAct / sports

It has been rested crown up and crown down to result in absolutely no difference.

I use the chronograph daily.

It advances a minute on the chronograph exactly like my 1861 movements, changing at 59.5 seconds.

The hour hand on the chronograph follows the markers as you would expect and aligns exactly around 3 mins before the hour. At between 10 and 5 mins it’s just shy of alignment.

Only thing I have noticed is an fairly metallic / bright sound when winding each morning. Nothing I’ve experienced before on any other manual wound chronograph, wether it be 861, 1861 or 3201 or 3203.

Takes the same 17-22 winds.

 

Well first off, that's nonsense. It really depends on what the movement requires, and given that there are many different movement designs out there, that sort of generalization is not practical in any real way.

I can't state the mind of people who made these decisions, however my guess is that the last two jewels added have little to do with any real wear issue. Even if someone clamps down the bridge with the screw before lining up the intermediate wheel peroperly, it's going to break the jewel as easily (or easier) than it's going to damage a bushing. There doesn't appear to be any practical reasoning for it, so I count it as being the same as the 18th jewel that was added to the 861/1861 in the coupling yoke. There used to be two bushings that supported the coupling wheel, and only one was changed to a jewel - the visible one. If that were done for wear reasons they would have changed both...

I don;t think this is a restart of the jewel wars, because there are "rules" to be followed, and one could argue that these are indeed functional, but that's very different than being of benefit.