Over the years there have been many conversations here and elsewhere regarding the reasoning behind Omega moving to the 861 from the 321. Many of these conversations make claims that the 861 was “cheaper” to produce, and the pillar wheel (known as column wheel by most, so that is the term I will use from here on) is often cited as the thing that caused the 321 to be so expensive relative to the 861.

Personally, I’ve never bought into this idea, and looking at what a column wheel costs as a spare part (the best indication we have about costs of production) my suspicions are borne out. The 321 column wheel is under $100 to purchase as a spare part. A column wheel for a 3313 is under $40, as is the column wheel for the 3300. The two parts of the cam (upper and lower) for the 861/1861 cost more than either of the column wheels for the 3313 or 3330, but are a little less than the column wheel for the 321.

On the new 3861, the two parts of the cam (what they for some reason call the upper and lower wig-wag on this movement) cost more than the column wheel for the Cal. 321.

So all in if we are talking about a part that ranges from less than $40 to a little more than double that, is this really a significant thing in the cost of making the movement?

Note that the remainder of the parts to make either system work is about the same in number...there's really nothing in it between the two.

So where are the supposed savings in the 861 design? There are a few things that would contribute to it certainly, and one is the balance wheel. They moved from an adjustable mass balance with an overcoil on the balance spring, to a smooth balance with a flat balance spring.

Here’s a 321 balance:



And an 861/1861 balance:



The main “wheel train and barrel bridge” is another area where changes were made, but these are less to do with the design of the movement and more do to do with streamlining manufacturability. An example is where the post for the column wheel was machined out of the brass plate on the 321 as you can see here:



It is a separate part made of steel that is pressed into the bridge on the 861, and I’ll show that later on. But in my view all these thing pale in comparison to the real savings in both manufacturing and servicing the 861, and the genius of the design of this movement.

The minute recorder.

Let’s look at the 321’s minute recorder parts. It starts with the chronograph wheel, and on the underside of that wheel is a finger:



This wheel and finger rotates once per minute, and is what triggers the flip of the minute counter. Now that finger is rigid, but it can be rotated on the post of wheel, and this is one of the adjustments that the 321 has on the chronograph. Now this finger is quite short as you can see, so it clearly doesn’t reach all the way across to the minute recording wheel to trip it, so there’s an intermediate step. This is done via something called the sliding gear – this is actually a subassembly made up of several parts and here is the top view:



Bottom view:



Side view:



So there are several parts here – a wheel, top and bottom plates, two bushings, screw that holds it together, and a bushing that goes through it. This bushing slips over a post that is pressed into the wheel train and barrel bridge. But we aren’t done yet...there is also the minute counting wheel, and then the minute jumper assembly. The minute counting wheel itself is no different from the 861 version, so I won’t spend a lot of time on it. But the teeth of that wheel are located and held in place in their 1 minute increments by something called a jumper (sometimes a paperclip is used in place of it even!).

So here is the wheel train and barrel bridge where the jumper is located:



The upper arrow points to a slightly fuzzy part, and this is the post that the rest of the jumper mounts to. The lower arrow points to an eccentric screw – this is for adjusting the jumper, so by turning this the position that the wheel rotates it's position slightly.

Now the parts that mount in this area:



The upper part is the minute counter jumper bridge, then the minute counter jumper, and then the screw that mounts the bridge to the post. There’s one last part – the minute jumper spring:



This spring wraps around a screw that sticks up from the bridge, and is what provides tension on the minute recorder jumper. So this spring helps keep the minute counter hand from moving as you are timing an event. The tension here is important, because too little will allow it to move around, and too much will add too much drag to the movement. In my experience, this spring is very fragile, and I’ve had many 321’s come in with the spring missing, and something else stuck in there.

More in part 2...

 

There are two other things – again on the bridge there is a "banking key" at the red arrow:



There are actually 2 there – the one to the left of the banking key at the arrow for the sliding gear is for the coupling clutch (also present on the 861). The round steel post sticking straight up in this photo, near the tail end of the red arrow, is where the sliding gear mounts.

The last thing is the sliding gear spring and screw:



The sliding gear pivots on it’s post, and this spring helps make that happen.

So how does all this work? Well, since the finger on the underside of the chronograph wheel is rigid, the sliding gear has to pivot and move out of the way of that finger when the chronograph is reset. If it didn’t, the finger would crash into the teeth of the wheel on the sliding gear during the reset. This means it has to pivot out of the way on reset, and then back in when the chronograph is engaged. Here is the 321 with the chronograph in the fully reset state:



I’ve added arrows at 2 locations. On the right the arrow is pointing at that screw sticking up from the sliding gear assembly, and you can see that the screw is touching the hammer that resets the seconds recording wheel and the minute recording wheel. The arrow on the left side is showing a gap between the tail end of the sliding gear, and the banking key. Now let’s look at the same area with the chronograph engaged:



Arrows at the same areas, so on the right you can see that the hammer has moved away, so the sliding gear is no longer being held up by the hammer in the retracted position. The spring has caused it to pivot down so that the finger on the chronograph wheel can engage with the teeth of the sliding gear, and when that wheel is flipped, it will in turn flip the minute counter. You can see that the gap between the tail of the sliding gear and the banking key is now gone, and they are touching. If you can visualize how this banking key works, if I were to turn it counter clockwise, it would allow the tail end to move up more, allowing the end with the wheel to move down more, and more deeply engage with the finger.

So as you can see there are a lot of parts involved in simply tripping the minute counter once per minute, and it certainly is costly to make all these small parts. From a servicing standpoint, there is the potential for problems, in particular if something gets moved, like one of the eccentrics or banking keys. You have the banking key for the depth that the sliding gear moves in to meet the finger, an adjustment to the radial position of the chronograph wheel finger, and the radial position of the teeth on the minute recording wheel (and by default the sliding gear wheel as they are always in contact) by adjusting the eccentric for the minute recorder jumper. Having adjustments is great, but having several sometimes means that some tail chasing can ensue, and time is taken up making these adjustments at service.

The 321 certainly isn’t the only chronograph movement designed in this way, as this was basically the standard practice at the time. There are some symptoms that indicate this isn’t set-up correctly, the most obvious one being that the minute counter starts to advance but then doesn’t completely flip. This indicates that the finger is not engaging enough with the teeth of the sliding gear. The opposite issue can happen as well – instead of flipping just one minute, the minute counter will flip two instead. Things can get more complicated on older watches that have not been treated well – I’ve had instances where the teeth of the sliding gear were damaged, and not all the same length. Trying to find the balance of being able to trip the minute counter without making it trip 2 minutes can be a challenge. Of course if new parts are available, it makes things easier, but that’s not always the case.

So now let’s look at the 861 – first let’s take a look at the main bridge:



The upper red arrow points to the post that the cam will ride on, and you can see that instead of it being machined out of the brass bridge it is a steel post that is pressed into the bridge. The lower red arrow points to a bushing – this is for the intermediate minute counting wheel (which is the 861’s equivalent to the sliding gear). Let’s look at the wheels in place:



So we have the chronograph seconds recording wheel on the left, the intermediate wheel in the middle, and the minute recording wheel on the right.

Here is the underside of the chronograph bridge:



You can see a post there, plus a spring – these two parts and the jumper that slides onto the post, replace the entire jumper system from the 321. So no thin fragile spring, no post in the main bridge, no eccentric, no plate, and no screws. So this alone is already a significant simplification of this mechanism. Like the very fragile spring on the 321, the flat spring here is adjusted to apply the correct amount of tension for the minute jumper, but this very rarely needs adjusting in my experience.

Now let’s look at these parts all in place:



No sliding gear assembly, no sliding gear spring and screw, no sliding gear banking key. But how does this all work? The upper left I have placed an arrow that points to the finger on the chronograph wheel. That wheel is the key. Here’s a closer look, but this time from the underside of the wheel:



I’ve added an arrow showing the same spot on the finger on the right, and as you can see the finger arrangement is very different from the 321. This finger is spring loaded, and the second arrow from the left is pointing at an arced flat piece that you can just see part of, and that is the spring.

This is genius.

Whoever came up with this I hope was handsomely rewarded, because this one small change eliminates a significant amount of complexity and cost in the movement.

I don’t know who first used this idea, but the 861 (and subsequent 1861, 3861) is not the only movement to use this concept. This is the chronograph wheel for a Valjoux/ETA 7750, and the finger on it is made of flat wire:



So it also can flex out of the way on reset, and as a result the 7750 also uses an intermediate minute counting wheel that is in a fixed position, and doesn’t need to move out of the way.

So are there drawbacks to this design? Yes, there always are to any design, but I would say they are very minimal in this instance. The only real potential failure is if the spring for the finger fails to work, and in the hundreds of these movements I’ve serviced, I’ve only come across this just once. I did make a video of the fault, showing how the finger collapsed rather than advancing the minute counter (due to a weak spring), and then showed the finger in detail, and then the movement working properly after a new wheel was installed:

Note that the other major area of the 321 and 861 chronograph mechanisms, the hour counter, are very similar with only very minor differences, so nothing there that will result in any real cost differences.

So although the column wheel is the most cited reason for the 321 being more expensive, and the 861 being made to reduce costs, it really isn't the portion of the movement that I would attribute to these cost savings - in fact I would say of all the changes it likely has the least impact on costs in manufacturing, and servicing.

Hope you found this interesting, and as always, questions are welcome.

Cheers, Al

 

i recall i read this somewhere in the past after i got my cb 321 in 2008 that there are 3 major parts that are absent in 861 or replaced/removed from 321. and of course, the latter is pure lemania.

 

Wow!
I have not had the time to read this in detail (It is still before breakfast so I have two more impossible things to do.) I look foward to re-reading this thread in detail. Especially as I am planning to re-case my lemana 1280 which has the cams but the traditional 'textbook' U shaped bridge.

Personally I never understood this nit. I remember the person who sold me my speedy said something about the movement grade. I was just glad to get it when I did and what I paid for it, probably because of this. (I am still wanting to find someone I can trust who can clean and regulate my speedy and restore the case pusher dust and moisture seals. I do not trust myself (especially after breaking the 650 pivot) to work on something that nice. After all there are watches and there are watches.)

I also have the Tissot with as I recall an 863 movement. So I am in great position to look at this myself with physical examples to look at. I still can not believe I put that 863 together from a loose box of parts. (was a lot younger then.)

-j
(I see it is now time for lunch. the net can be so seductive.)

 

Well, if you read the posts, clearly those aren’t the key things.

 

Thank you for posting this, Archer.

 

Thank you @Archer

 

I find these posts very interesting, thanks for your work!

May I ask why the 861 caliber don't have these problems of the hour counter (creep...) like the 321?
Thank you!

 

The hour counter creep is an adjustment of the break lever. Both calibers can have it.....

 

It happens to the 861 also, and I go over the way this works, and what the causes for it are in this thread:

The mysterious Speedmaster hour counter | Omega Forums

The adjustment of the hour counter stop lever (a.k.a. brake) is rarely the cause of hour counter creep in my experience. It's usually from lack of maintenance, poor servicing, wear, or damage.

Cheers, Al

 

Just sat down to absorb this. Hate to admit that I had to reread sections to figure it out.

This explains some of the reasons why I have heard that the 321 can be difficult to work on. I experienced something like this when i had my 321 in my Seamaster serviced. I had to send it back a couple times because the chronograph would get stuck. It'd start and stop but jamb and couldn't reset. He finally sent it to someone else who said it just needed an "adjustment." It makes me think that it involved the mechanism you described for the minute counter. I have since been sensitized to thinking 321s are not as robust and I hesitate using the chronograph now.

It looks like the banking keys are screwed into the bridge? But if so, then it seems like it'd be tricky to get the thread tension just enough at the right position for the key angel? So adjusting is turning the threads, which is then understandable how they might wear and loosen over time. The tolerances on these little parts is remarkable.

I started wondering if the simplified minute counter of the 861 could have been added to the 321 and the column wheel kept, but then realized the hammer is connected to both so that would mean more changes, which may be why there is the cam system. Makes me wonder which came first? Did the switch to the cam prompt the change to the minute counter or did the change to the minute counter prompt the change to the new cam? Do you have other threads that compare the column wheel function to the cam?

Thanks for spending your time to share this info. We know you have your day job and writing this takes time. It's pretty intriguing and appreciated. I can feel the wheels turning and bit by bit it's making more sense.

 

I wonder if the removal of the column wheel was 2 fold. As a non capped column wheel is technically a weak spot and hence not allowed on watches with a Geneve seal.

So it was slightly cheaper and stronger, with the loss of slightly smoother button action.

 

Is a smoother button a loss? I kind of like it. I wish it was more like the Excelsior Park.

 

The banking keys are pressed into the bridge, so not screwed in. They can be quite difficult to turn, and sometimes you will see them broken from someone using too narrow of a screwdriver in the slot. Of course they have to be tight so that they don't move during use or due to an impact.

I'm no expert on chronograph history, but my gut tells me that the cam likely came first, and these changes are independent of each other. The second part of that can be confirmed by chronographs that use cams, but still have the sliding gear arrangement. There are a number of these - here's an older photo (excuse the photography, but I wasn't as good at taking photos back them as I am now) of a Landeron 48:



You can clearly see this is a cam operated chronograph. Now it may appear to resemble the 861 in that the intermediate minute counting wheel appears to be fixed in place, but it's no - it's mounted on a sub plate of sorts that pivots:



There are others, so the Landeron 51, Venus 188, and of course the more common Valjoux 7733 or this case 7734:



Upper arrow points to the cam (most of it is under the larger levers) and the other arrow points to the sliding gear.

Now I don't recall seeing a chronograph that has a column wheel, but not a sliding gear, at least not one that has the traditional layout of the minute counter. Of course there are other arrangements out there for minute counter - the central minute counters are a different animal, and the minute counters that constantly turn are also, but I'm referring to those that are tripped once per minute.

The can or column wheel is just a switch. People put far more importance on this than it deserves in the collecting world. Here I have an 1861 with the parts needed to switch the cam in place, so you can see how it works in isolation of all the other parts:

Now the 321 column wheel:

One toggles back and forth, and the other rotates. They both push various levers to make the chronograph operate. Their purpose is only that.

In terms of differences in operation there really aren't any other than "feel." Some people refer to the column wheel as "smooth" but to me personally, I find them more "mushy" than smooth. With most cam systems, the resistance is higher and the switch happens with an abrupt snap. The column wheel tends to have more gradual resistance, which I feel makes it less predictable when the chronograph actually starts. For me personally, the cam is better suited to actually timing something accurately, but of course that is a secondary thing for collectors mostly.

Cheers, Al

 

Toggle vs turn



Thanks.

And good morning, bright eyes!

Dave

 

So many questions that I didn’t know quite how to formulate or who to ask; now answered. Brilliant content. Thanks.

 

This is an interesting and informative thread. But if cost wasn't the major consideration in changing from a column wheel to a cam system what motivated Omega in the mid-60's to invest in the research and engineering to redesign the traditional column wheel system that had been used for generations in chronograph movements? The Swiss don't do anything outside the box, they stick with what works, and a column wheel works. Why invest time and money in a new mechanism when the old one works just fine? The answer is probably lost to history but something motivated Omega.

If this change had happened a few years earlier the watches submitted to NASA for testing would probably have been the newer cam jobs, in which case no one would have cared about the old 321 movement today, they would just be a musty, dusty relic of Omega's history and not really worth collecting. Timing is everything.

 

This is intriguing. Omega does have a reputation (I believe) of continuous improvement so it's understandable that they might make this innovation without exterior pressure. Yet it was a (seemingly) big change, so there must have been a lot of discussion. It'd be interesting to know the drivers.

@Foo2rama mentioned this hint below, but it was lost on me. I would like to know more.

"As a non capped column wheel is technically a weak spot and hence not allowed on watches with a Geneve seal."

 

@pdxleaf

so the column in a column wheel can break.



one of the requirements on watches that carry a Geneve seal like Patek is that the wheel is capped which is more expensive to make but is much stronger.

 

The change was made for reliability. Cam operated chronographs were around before the 861 ever came along.