A few days ago I went to stick a new strap on my watch, a vintage Tudor Oysterdate from the 70's when I noticed it wasn't keeping time... It actually wasn't making it beyond a few ticks. I tried everything I could, but at home my only tool is a springbar tool, so it would have to wait....
I bought this watch because it was a good deal and I loved the style and fluted bezel. I have really tiny wrists so the 34mm case size fits them perfectly, I just can't comfortably wear a lot of modern watches.
I got it to school and began getting input from other classmates on potential diagnoses, we suspected the gear train or the mainspring. The mainspring is a long and tough metal spring that gets coiled into a small drum, when wound it contains considerable force and is also the source of energy for mechanical watches.
I got it to my professor to hear our potential thoughts and get his hypothesis. He masterfully checked out a few areas and "probably a broken mainspring."
He handed it back to me. He also cautioned against being hasty in taking apart watches with value before having more training, giving me anecdotes of students past who caused considerable damage to some of their rare and valuable watches. I think he saw that look in my eye and knew that I wouldn't be deterred.
Later, I solicited some guidance from a second year student, the second years have been working on the ETA 2824 movement, a very widespread and, to some degree, standardized movement. The Tudor that I was taking apart runs on the ETA 2784, which is a very similar predecessor to the 2824 (I already just say random numbers when referring to movements in hopes that someone will understand, these are going to be annoying to memorize). So at the very least, it would be good practice. Real world wear and tear on a watch movement is quite different than simulated wear and it varies wildly from watch to watch; this is where the problem solving skills of the watchmaker come into play.
Even the case was a challenge that got a few of us rubbing our heads together. These older cases depend on the bezel to create pressure to secure the crystal. Eventually with some fine razor blade skills and some gentle bezel removing action from the slightly scary Rolex bezel remover, it was all taken apart. A film of glue or gunk or both had made this tight fitting bezel even tighter on the case.
Pulling apart the movement it was pretty clear that it was in desperate need of a service. The oil was dry and and formed gunk all around the jewels and gears/pivots. I got to the mainspring barrel, opened it and discovered my professor was correct, the mainspring had indeed snapped. I let him know that he was right, he then sent me on the guided path of a thorough and full service of the watch. I got it all disassembled and began a preliminary cleaning (before it goes into the ultrasonic) he then instructed me to inspect each pivot of the gear train, instead of helping me get the watch back on my wrist as quickly as possible he was going to help me learn as much as I could, especially about how vintage watches wear.
The photo above is the gear train all aligned and stuck in a piece of Rodico, which is a sticky tack like material with a plethora of uses. Aligning the pivots like this lets you easily view them under the microscope without having to fuss over each one, saves a lot of time. These are very small components, and even mishandling them can quickly destroy them.
Above is a photo of a pivot. These are really tiny (this one is 0.11mm in diameter) and fit inside of tiny rubies with holes cut out so they can spin with low friction and wear. These points of interaction need to be kept properly lubricated or else you can damage or accelerate wear within your watch. This is why you hear people talking about regular service intervals for mechanical watches.
The pivots were mostly okay, the 4th wheel had some wear, which presented itself as a black line under the 50X microscope. When the pivots wear down it affects the timekeeping of your watch, if it gets bad enough they need to be replaced, but before they get too bad you can do something called pivot burnishing. Using a burnisher you set up your wheel and pivot on a special lathe, the burnisher doesn't really cut material but mashes into a uniform plane; if you do it right.
Like I mentioned earlier the pivot has a diameter of 0.11mm, it needs to be this size to function. To burnish it, the cup the pivot gets placed in has a diameter of 0.10mm, so a little tiny bit of the pivot sticks up. You then spin the lathe with a handheld bow and simultaneously push the burnisher to-and-fro to polish the pivot.
I got a quick lesson and demonstration from my professor on how to burnish pivots. Once the pivot is installed on the lathe (almost the entirety of the operation) you're ready to go, but the burnisher and jig obscure your vision of the wheel 100% so this is completely based on feeling. I'm familiar with feeling certain aspects of watchmaking, like applying hands. At first hand application was very challenging, then you began to understand how much pressure to apply and wear to apply it, it's less about seeing it, than it is about feeling it. That was tough to learn, and this was going to be even harder. If I burnished this to 0.10mm from the 0.11mm it would be useless and I'd need to buy a new one.
My professor, Dave, made 2 passes with the burnisher during his demonstration, now it was my turn. I took the wheel after his couple passes to the microscope and we checked it together, it needed a little more work. It was now my turn. I painstakingly got it mounted, made sure it was ready to go and gave it a spin. Burnishing is a bit like patting your head and rubbing your belly. The bow goes down, the burnisher goes out, bow comes up, burnisher comes in BUT DON'T FORGET TO FEEL THAT PIVOT. I got the burnisher locked on the pivot and Dave quickly pointed out it wasn't flat, oops! Flattened it and got the bow spinning the lathe "MOVE THE BURNISHER!" Ok, well Dave didn't yell at me, he never yells, but I was patting my head and not rubbing my belly. I got the burnisher going in sync with the bow, felt the contact with the pivot, such a subtle light feel you aren't sure if you're imagining it. And after 3 passes I decided it was time to check it.
The pivot had been burnished! It wasn't a super perfect job (photo is the one with the red arrow up the screen) but it was better than what it was before, and I didn't destroy it. So I'll chalk that up to a success.
The watch parts have all gone through the ultrasonic, next step is reassembly and oiling as well as one I'm really excited for, case refinishing.
To be continued....