Omega CoAxial Assembly 3330

[hofnerpres]

A couple of things here which cost me most of yesterday to learn and may help others as more of these movements age and start to need servicing. There is a lot of Valjoux 7750 here so some parts will be obtainable but please be aware that any damage could be a real headache. Worst case you may have to resort to buying a used replacement movement which are available at around £1000. If you are doing the job for a friend - are you happy to give them back a good looking paperweight ? The CoAxial Escapement parts are Omega only and thus unobtainable to watchmakers outside their AD network. Still willing to take the risk ? I did and got away with it but the stress levels took the fun away so I will hesitate to do another. The main challenge is assembling the balance safely and doing a professional job of the precise lubrication required. Have a read of Omega's Working Instructions No 40 - it's on Cousins site but and Omega search will not find it. Search under "Working". You will need a good Stereo Microscope and a very experienced oiling technique.  Mr Daniels and Omega had a struggle over many years to get this escapement developed enough to suit mass production. It's more complicated and less tolerant to imprecise clearances and wear rates when running at 28,800 were an issue. Hopefully all resolved on the latest variations but only time will tell. The main advantage of not needing oil was certainly lost early on in the expensive battle. So still feeling lucky punk ?

The struggle to get things reliable has left a development trail of three main types :

The far right Starfish style is the latest. Mark has an excellent video assembling a 2500 Omega which has that variation. The 3330 has the middle one - early 3 level and seems to need a different installation approach. Whereas Mark comes in from the left and then turns clockwise - the 3330 seems to favour the opposite : Comme ca :

You have to understand with this design the roller assembly is upside down and also has its own vulnerable pallet jewel:

Winding the balance cock in anticlockwise keeps that tiny jewel out of harms way whilst you fiddle the roller jewel into the fork. You have to get the balance arbor sat in the baselate pivot jewel and the fork around the roller jewel  before you swing the cock into place otherwise it is very easy to get things in a jam. Easing up the wheel in order to get a fit often works with a conventional escapement but this is upside down. Check things are in place under the microscope before applying any power. Now this is hard enough but when tried with any power wound on it proved impossible. With this version of the CoAxial the fork will sit stubbornly in one set position - it will not flick obligingly between the banking stops. At this point you will start to imagine you have broken the movement. Did I mention stressful ? Do not despair - this appears to be normal. LET DOWN THE POWER before assembly. The fork now swings freely and it will go together. Check things are in place and apply some power. The design seems to rely on inertia to get things pulsing both ways.

And another possible snafu :

The pallet fork bridge is retained in precise position by the two ears shown above. Mine were so tight that they needed a crow bar to release. When trying to assemble this meant the bridge was sitting with one ear in and one ear out which was sufficient to prevent the two pivots from dropping into place. I had to just stone away a tiny amount of metal to get a good push fit without any slop. Dangerous work. Neither was I impressed with the amount of play on the pallet fork pivots once assembled - nothing worn just not as tight as it should be.

To be fair to the the good people at Omega it runs very consistently - almost no positional variation - just like a decent Rolex.

Hope this diatribe will amuse the experienced and alert the nervous. Neil.

[hofnerpres]

Happy ending pictures. Making me think that quartz makes sense when it comes to Chronograph complications. I wince every time that second hand wacks back around on reset. Very handsome piece with those large subdials.

[Knebo]

Thanks for sharing all of this! I'm sure it'll help me or others in the future. 

Out of curiosity, does your Weishi 1000 have no problems reading the Coaxial? Certainly the amplitude isn't correct, but otherwise looks like a normal reading. 

 

2 hours ago, hofnerpres said:

wince every time that second hand wacks back around on reset

Haha, I know what you mean/feel! 

 

 

[praezis]

19 minutes ago, Knebo said:

Certainly the amplitude isn't correct

As it is the only issue with coaxial …

[hofnerpres]

Fair comment guys. The Timegrapher was still at the usual 52 degrees instead of the 38 l believe should be used. Frankly l tend to use slow motion on my phone and do things the old visual way. It looked very healthy. I do occasionally get odd amplitude readings from some watches on that machine .

[AndyGSi]

56 minutes ago, hofnerpres said:

Fair comment guys. The Timegrapher was still at the usual 52 degrees instead of the 38 l believe should be used. Frankly l tend to use slow motion on my phone and do things the old visual way. It looked very healthy. I do occasionally get odd amplitude readings from some watches on that machine .

Out of interest can you check this on the timegrapher @38 deg as I'd expect the figure to be low 200s.

[praezis]

8 hours ago, AndyGSi said:

Out of interest can you check this on the timegrapher @38 deg as I'd expect the figure to be low 200s.

It can be calculated easily: display @38° would be 254° amplitude.

Frank

[AndyGSi]

19 minutes ago, praezis said:

It can be calculated easily: display @38° would be 254° amplitude.

Frank

How would you calculate this as I didn't think it was a linear result?

[Neverenoughwatches]

As a ratio of amplitude . 347/52 . Supplies a ratio of approx 6.67.   Then an inverse calculation 38 × 6.67 = 253 ish.

253.577 to 3 decimal places. Frank's 254°

1 : 6.67.....

[AndyGSi]

3 minutes ago, Neverenoughwatches said:

As a ratio of amplitude . 347/52 . Supplies a ratio of approx 6.67.   Then an inverse calculation 38 × 6.67 = 253 ish.

253.577 to 3 decimal places. Frank's 254°

I thought that's how he'd worked it but in my experience it's not
linear and the further away you are the greater the discrepancy.

I've had ratios of anything from 4 to 10 deg amplitude per deg lift.

[Neverenoughwatches]

A timegrapher calculates Amplitude from its set lift angle and elapased time between impulses. So lift angle can also be calculated from an Amplitude. 

1 minute ago, AndyGSi said:

I thought that's how he'd worked it but in my experience it's not
linear and the further away you are the greater the discrepancy.

I've had ratios of anything from 4 to 10 deg amplitude per deg lift.

I wouldn't think the ratio would change on the same movement.

It might do with different power reserves

It is linear, to within a fraction of a degree taking into account minor amplitude changes from one lift angle setting to another. 

The lift angle and amplitude are just ratio values of 360° . Parts of a pie....and speaking of pies..it's time for breakfast

[praezis]

1 hour ago, AndyGSi said:

I didn't think it was a linear result?

In fact it is a linear ratio (easy, isn‘t it?).

Ampl= LA / sin(2pi *t /T)

In real life you can ignore sin and use the angle (2pi *t /T) alone.

Frank

[hofnerpres]

Oh dear. I used to believe machines were logical. Enough watch work will get you to believe that some pieces are out to get you. Then l read up on quantum theory and now l know it’s all smoke and mirror.

Now we are all breakfasted here is the picture at 38 degrees. It matches what l saw manually. Wish all my efforts looked this good. 

 

[JohnR725]

On 2/28/2025 at 3:30 AM, hofnerpres said:

Have a read of Omega's Working Instructions No 40 - it's on Cousins site but and Omega search will not find it. Search under "Working".

A lot of times one of the best ways to find thing is is to simplify your search and working works really well at least for Omega working instructions then I assume that you got number 54? Something helpful when you're working on these watches.

On 3/5/2025 at 1:52 PM, hofnerpres said:

The Timegrapher was still at the usual 52 degrees instead of the 38

I was just now looking at the Chinese timing machine manuals and it doesn't mentioned coaxial? I'm sure I've seen it in the advertisements when there selling the machine? The reason I ask is witschi machines typically have a setting for coaxial I wonder if that makes any difference at all? I know some of the newer machines actually do say coaxial this was snipped out of the watch expert two manual.

 

[praezis]

3 hours ago, JohnR725 said:

That is typical Witschi: make it mysterious, don‘t tell what exactly you will do (e.g. ‚rate‘).

The coaxial esc. shows narrower gaps between pulses in the esc. noise, so the TM may have problems separating those pulses in standard mode - or may not, depending on electronics and software layout. 
True is, this will affect amplitude numbers only - not rate or the highly important beat error .

Frank

 

[tomh207]

18 hours ago, JohnR725 said:

A lot of times one of the best ways to find thing is is to simplify your search and working works really well at least for Omega working instructions then I assume that you got number 54? Something helpful when you're working on these watches.

I was just now looking at the Chinese timing machine manuals and it doesn't mentioned coaxial? I'm sure I've seen it in the advertisements when there selling the machine? The reason I ask is witschi machines typically have a setting for coaxial I wonder if that makes any difference at all? I know some of the newer machines actually do say coaxial this was snipped out of the watch expert two manual.

 

I have seen the 1900 being quoted as coaxial compatible too, nothing I have seen in the manual or the device either for something like a specific mode for it. I vaguely remember seeing conversations elsewhere that newer 1000 machines could do coaxial as well but never anything definitive.

 

Tom