AWCI Modern Mechanical Chronograph

I haven't totally introduced myself, but have been following these forums for a while. I am watch collector of mostly Omega's, though have been getting into some other brands as well. A big part of the hobby for me is the repair side. I started with reading as many books as I could, then took all 4 of the TimeZone online classes. They were good for a start, but I knew I wanted to learn more.
I next attend the Introduction to Watchmaking class at the AWCI, a week long class that covers the 6497 movement, I learned far more in that week then in my previous 2 years of learning on my own.
Next was the AWCI Swiss Lever Escapement class, a good part of that class was diagnosing watches with faults preinstalled by the instructor. It was tough, and I certainly felt humbled at times when I didn't find and correct all the faults.
This week is the class I've really been looking forward to, It covers mostly the ETA 7750 and 7751. We only have 3 people in class, so the instructor plans to cover other things as well, one of which is the Lemania 1873, also know as the Omega 861.
Today was theory and history, then adjustment of the chronographs system. I didn't get a lot of pictures as I was too busy learning.

The class provided watch is a Tissot, which has been apart many times. It has scratches, marred up screws, and many other things that shouldn't be happing in a repair shop, though often do based on some of the "serviced" watches i've purchased. I also brought along a Sinn 144 from my collection that doesn't run. So far I've found 3 problems with it, It seems to have had a hard previous life. More on that watch later.

All our work is inspected by Tom, the instructor, under the microscope and displayed for all to see.

Pictured is a grossly misadjusted minute jumper. With the hammer down on the heart cam of the minute counter, it should be touching two teeth.
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This is a video of the function check of the chronograph wheel jumper "finger". The finger had previously been adjusted at it's beak, which should never be done. I got it adjusted to Tom's approval however. I found its interesting how one of the functions of the finger is to take the slack out between minute counter driving wheel and minute counting wheel, making the minute counter hand jump cleaner when the finger comes back around and starts engaging the minute counter driving wheel at 58 seconds. You can see the slight nudge right after the finger clicks the wheel over one tooth.
I didn't get any photos of the depthing adjustment of the oscillating pinion, but will do so tomorrow. The engagement depth is 2/3. It must be checked through a full 60 seconds, as the chronograph runners are often not as concentric as you would expect. In the watch I was working on, the 35-50 second range was tighter than the opposite side. More to come tomorrow.

Joe

Nice write up.

👍

I like your choice of screwdrivers 😉 (or are they school items?).

I have a set of Bergeon, Horotec and VOH. The VOH are the best, after I get the blades dressed they really hold up well. For all classes beyond the introduction class, you are to bring your own tools. Tom is always happy to provide us with anything we don’t have or forgot.

Yep, my main set are VOH, they are superb. I dress them on a acrylic sheet that has three strips of adhesive polishing film.

Picked it up here.

Some highlights from day two:

Then center chronograph second hand is off already, using some hand levers and a dial protector Omega calls "pants". I'll get a picture of that tomorrow. The chronographs seconds hand comes off by itself, then the hour and minute hand are taken off together. All the sub dials hands then come off.

All of the hands are stored in a nifty little box, which we all received as part of the class. The sub dial hands are sorted so they can go back onto the locations from which they came from. Those three hands can technically fit in any sub dial location, though often they may be different colors or designed. With the Omega 861, the hands will only fit where they came from.

Day and date disc. I need to learn my German days of the week. I didn't get a picture of the jumpers for these discs, they are different sizes.

My Sinn was equipped with the older style hour counter brake, on the left in the picture. It will receive the new version that is on the right.
We then were busy with many checks, and Tom made us practice anything tricky 2-3 times, such as removing certain springs or bridges. I was too focused on what we were doing I didn't take picture.

Everything is apart, balance is mounted back onto the main plate before everything goes through the cleaning machine. We practiced winding the mainspring and inserting it, as well as adding braking grease to the barrel walls. We kept doing both until Tom was happy with the results.
We will be using new main springs for the actual reassembly .

Slight pallet fork slot wear on the left, extreme on the right.

Harder to see pallet fork wear. This problem has been seen in movements from both ETA and Rolex. According to Rolex, the roller jewel had too sharp of an edge where the flat side meets the curved side of the "D" shape. In fast beat movements it is supposed to be a smooth shoulder at that location. If this wear is seen, both the pallet fork and the roller table with the roller jewel are to be replaced.

A check of hairspring centering under the video microscope. Close, but not quite perfect yet.

One of the pivots of the oscillating pinion, along with one escape wheel pivot and the pilot on the end of the stem were broken. This watch received a severe shock at some point.

Oscillating pinion depthing check, good in some spots, a little too deep in others. This chronograph runner isn't perfectly concentric.


Broken oscillation pinion in my Sinn.


What happens when you don't maintain your watch, the lubricant dried up and the barrel arbor has eaten away at the bridge. A bushing may be needed, or bridge replacement.

Cleaned and getting ready for assembly. Plus today’s lunch selection.

How many times have you been to Gold Star so far?

Tom loves his Gold Star....

Gold Star closed! Tom is very sad...It was always the Wednesday lunch location.

“my date is fat, but I hope some day she/he will be thin.”

I bet he won’t resort to Skyline either!

Yep, that was Tom's little phrase to remember the difference. I'll suggest Skyline tomorrow and see what he says! 😉

The pants used as a dial protecter. It gives you the height get the central chrono hand off. It is made from layers of the thicker static cling material.

Inside of a reverser wheel. You shouldn’t take them apart, this was part of a demo on how they work and how to lubricate them. Just two of the little beaks have a little 9010 applied. There is also a dip and dry product. Replacement is always a good idea as this little guy changes direction between 10-100 million times per year.

One of the pawls installed into the reverser.

Complete reverser wheel.

I know this is an Omega forum, and I’m not really into Rolex, but yes this is what you think it is. And no, I don’t own it, neither does Tom.

Pants - yes made from layers of plastic than can be added to or peeled off to get the right height:



And the solution for reversing wheel lubrication is Lubeta V105:



Dip the wheel, blow off the excess, and let it dry under a cover.

Still making the trek each week to Casker? I always ended up buying a bunch of stuff to take back with me. We usually hit the pizza place near there for lunch.

Say hello to Tom for me...

Cheers, Al

One trip to Casker. I picked up the Horia 7750 movement holder. Tom told me to throw my cheap plastic 7750 holder in the garbage. 😀

Some photos from the AWCI mobile classroom, super awesome setup inside.
Oscillating weight bearing testing. My bearing was shot and already replaced. I used a very small drop of HP-1300 to help eliminate the typical 7750 wobble. Breitling uses 2 drops on the bearing for this reason. The tech guide specifies 9010. It is a very small amount, too much and the balls slide instead of roll inside the bearing.

Vertical clutch stuff covered today, as well as some modular chronograph stuff. We went over about 60 minutes of 861 stuff, they have Heuer labeled movements.

The Sinn is running Great! I was happy with the hand alignment, I got it 99.5% perfect. Without a loupe it looks perfect.
Measured over 5 positions,
+2 at full wind
+3 full wind chrono on
+2 full -24 hours
+2 full -24 hours chrono on
That’s some great isochronism.
The delta when looking at full wind and full wind -24, chrono off for both, was 12 seconds.
Amplitude at full wind dial positions was 290 degrees. Chrono on dropped it by 10-13 degrees on average.
The 7750 can really produce some good timing numbers with a little work.