A Day in Watch School

Before we get to the watches though, we have a lot of pivot gauges to make. By the end of the 2nd quarter, I had only completed a couple of straight pivots and they were not very pretty. It took me probably 20 or so attempts before I had 10 I was happy with and it was about that time we took the second intermediate exam. We had 8 hours to cut the handle, shaft and pivot of a straight pivot gauge and then shape and burnish the pivot to perfection. At first, it seemed like an incredible challenge but, by the time we actually got to the test, I think most of us probably could've completed two or three in that time.

I focused an inordinate amount of time and attention on getting a near perfect cut finish on the handle and shaft of the gauge. As we were not allowed to finish those surfaces (the graders wanted to see our cutting skills), getting a consistent surface was a challenge. While a consistent finish with some machining lines would have been acceptable, I spent many hours experimenting with different cutting and sharpening techniques in an attempt to attain a perfect mirror finish with just a graver. Eventually I found that using a carbide graver that had been finished on a glass lap with diamond paste I could get some pretty good results. I picked up a few cutting tricks from some of my classmates along the way and ultimately just spent a lot of time on the final hundredth of a millimeter of the cut surface getting a glossy finish (the pivot gauges shown are not the best examples). This frankly was not an ideal use of my time as my cutting technique surpassed my pivot polishing technique which was of course the real point of the exam. Obsession is a dangerous thing.

After we were through with the exam, we moved on to conical pivots. In watches, conical pivots are used on balance staffs and other small pivots that ride on cap jewels. The conical shape helps to give them a little more strength but that didn't keep us from breaking many of them in the process. The trick is to put just enough pressure on the workpiece while turning it in the jacot tool to burnish the entire straight and conical portion of the pivot without breaking it (click here for a little movie of Viet burnishing a pivot on the jacot tool). When the pivot you're trying to burnish is under 0.08 mm in diameter, it gets to be quite a challenge. 

I took a page out of George Daniels' "Watchmaking" and made a safety guard to assist me in this endeavor. A safety guard is a steel finger that limits the lateral motion of the burnisher. By properly positioning the safety guard, you can keep from putting too much pressure on the shaft of the pivot while allowing just enough to burnish the curved portion. The time invested in manufacturing this little tool was well worth it. While one of my classmates broke easily a dozen pivots before getting one burnished properly, with the safety guard in place I only broke two or three total. By the time we were done making pivot guages, I had a handy little assortment of all sizes between 5 and 24 hundredths of a millimeter. These little guys will come in handy when trying to select jewels or determine pivot sizes in the future.

The next step was to start cutting balance staffs. To make a functional balance staff we had to put together all the cutting and burnishing skills that we had gained up to that point and achieve an even greater level of accuracy. As the overall length of the balance staff is possibly the most critical measurement, to cut two or three steps and shoulders on each side of the staff accurately enough to allow the finished product to meet tolerances of a few hundredths of a millimeter requires considerable skill. In order to ensure that both sides of the balance staff are perfectly concentric, the entire staff is typically cut without removing the piece from the lathe. Because of imperfections in the collets and other variables, a slight error could result from removing it from the collet halfway through and reversing it to cut the other side.

I found the challenge of cutting the second pivot without breaking the workpiece off quite invigorating and made a double-decker version for fun (of course neither of the staffs were accurate enough to use anyway).

After balance staffs (and about 8 months of other manufacturing projects), we were given something completely foreign to us. As it was explained to me, it is called a "watch movement". Apparently, this one was code-named ETA/Unitas 6497. We spent some time taking it apart and putting it back together to familiarize ourselves with the parts in a basic handwind movement. Then, before getting too used to this fiddling with watch parts business, we proceeded to fabricate a clutch lever for it. It seemed like the clutch lever it already had was perfectly functional, but I lack the years of experience our instructor has.

This was a very entertaining project and, of course, quite challenging. Making watch parts is fun. Our instructor, Elaine, was kind enough to provide us with some paper patterns (just to save us the agony of scanning and/or photocopying the clutch lever ourselves) and we then had to cut one out of steel, file it to shape, harden it, temper it to blue and then finish it. Elaine mentioned to me that straight graining and beveling it would not be appropriate, as it would not match the other keyless levers in the watch. Just for her, I turned it in entirely polished. Then, after she graded it, I straight grained the top and beveled the non functional edges. It was only a marginal success on all counts. The portion of the lever that engages the clutch was not quite wide enough and so left a little slop in the handsetting position and the beveling was not as consistent, pronounced or highly polished as I would've liked. It was a learning experience to be sure.

Next, we were given another one of these "watch movements". This one's code name was ETA 2892. We spent some more time taking it apart and putting it back together. After we had reached the point where we could put all the parts into a big pile and successfully put it back together we had gained enough familiarity with the mechanisms to better understand the many checks, adjustments and repairs that we would soon encounter; not before some more manufacturing though.

For the next project, we were given a choice. In order to gain some experience with jewelling and bushing, we could either make a jewel plate with four different sized jewels/bushings in a straight line at very specific distances from each other or we could make a little wheel sandwich. The wheel sandwich was two plates with two wheels between them, fixed in jewels and bushings at the appropriate distances to allow the wheels to interact in a power-train-esque manner. The wheel sandwich sounded a little more like a watch to me so the decision was easy. My classmates Viet and Rebecca also chose the sandwich and Steve (our classmate who is so far ahead he is performing complex repairs on complicated antiquarian pieces) had made the sandwich so long ago he could hardly remember having done it.

Viet and I encouraged each other dysfunctionally to come up with bridge designs that were fabulously complicated to manufacture and finish properly and we were sweating the final few hours of the week allotted for the project. After spending several days cutting, filing and polishing some complicated curves, all the real jewelling and bushing took place on the last day. We just plain ran out of time to add any anglage, so we'll have to do that later. We were both more-or-less happy with our completed projects though and Viet's dad (a watchmaker) was delighted when Viet gave him his figure-S shaped wheel sandwich for Father's Day.

At this point we were deluged with these "watch movements", receiving a kit of ten movements in varying sizes. These included a tiny, ladies' Bulova 1020.30, some "standard grade" manual winds (standard grade is apparently the appropriate euphemism), a lovely little Longines movement, a few ETA autos, a Unitas 6497 and a Buren Cal. 03 (I think that one's a bomb timer, large, no mainspring barrel (or even a place for one)). We took them apart and isolated the barrels from the rest of the parts and, after removing the mainsprings, surrendered the barrels and barrel arbors to Elaine who maliciously "adjusted" them. Maladjusted that is. She altered the sideshakes and endshakes and returned them all in non-functioning order.

If there is a better way to learn how to check, diagnose, adjust and repair specific watch mechanisms, I don't know what it is. We learned how to check the play of the barrel arbor laterally and vertically and how to adjust the barrel drum and cover until we had some lovely, free spinning (and true spinning) barrels once again. Using a staking set to close the holes when they were too loose and using smoothing broaches to open the holes when they were too tight, polishing the bearing surfaces with pegwood and polishing compound and truing the drums and covers until the barrel would spin smoothly and freely around its arbor was a laborious process of many frustrations and a very steep learning curve. The fact that these movements have sometimes been through many years of students made it all the more difficult as you occasionally had to face the fact that a given barrel drum or cover was simply un-serviceable.

Having many years worth of barrel checking and adjusting experience condensed into one week’s time was definitely an eye opening experience and made me look forward to the rest of the course all the more. The depth with which we examined the functioning of the basic power source of a mechanical watch was truly invigorating and I anticipate greatly focusing with such intensity on the many other mechanisms that make up a mechanical watch movement. Heck, I'm even kinda looking forward to the quartz business.

_john davis 7-20-2002 

Copyright July 2002 - Mr. John Davis and ThePuristS.com - all rights reserved