I have written quite a bit. But as I write I realize I am not easily able to say "just press the I believe button", and I do not have the full scientific knowledge to back up my understanding on hand.
I enjoy sharing, which is the reason I originally posted this thread, to share a process that I enjoy as a watchmaker, and that I thought others would enjoy seeing as well. Be prepared, it probably will not be the only time I do this! My intent was never to come here and say "do it my way", but only to share some of the work I do.
I have decided that it is best if I simply say, this is not what I learned in school, and until I am able to be an instructor, that I am able to best write and instruct what I have learned, I should not get on the podium.
So I will though share my background. It is my sincere hope that my credentials help everyone understand that although you may have a different way that you do procedures, I too have my way, and it is the way that I was taught, the way that I understand, and I am recognized for the way I do my work. In no way am I saying anyone is wrong, as I just said earlier, I lack the ability to demonstrate in a way as I learned in school, I can not properly teach static and dynamic poise as I learned. If I can not properly convey my understanding, I can not say your understanding is not right. But I can say I learned differently.
I was Active Duty in the US Navy for 20 years and then I was retired. I joined when I was 17 and a Junior in High School as I knew it was what I wanted to do, and went to boot camp after I graduated from High School and turned 18. While I was in the Navy I started my career as a Data Systems technician specializing in the Link 11 system and ended my career as an Electronics Technician (as the DS rate was phased out), my primary specialty as an IFF technician, but I also worked on GPS navigation systems, etc. I had quite a few NECs. I spent nine years of my career overseas.
Since my Grandfather showed me an American Pocket watch when I was five I was hooked on watches pretty much my whole life. While I was getting close to being retired from Active Duty, I was considering a career in watchmaking. And as you can tell I took that leap. It is not uncommon in America that most professional watchmakers are second careers. In America it is not common to grow up wanting to be a watchmaker, as it is in Europe, and the training infrastructure is simply not the same as Europe for watchmaking. Watchmaking was not a career option for me out of High School so it is also a reason why it is a second career for me.
I applied and was accepted to the Lititz Watch Technicum in Lititz, PA. It was a two year school, with more than 4000 hours of training. The first year concentrated on micromechanics, where I learned how to use a lathe, drilling, hand filing, sawing, hardening and tempering steel, working with brass, friction, rivets, screws, threading, bevels, line finish, polishing steel, sanding, burnishing, boring, broaching, finishes... I can go on and on. I had a clock project first, where I took a common Hermle clock movement and converted it to a straight line clock.
I had to make drawings for all of my early micromechanic projects. One set in a 2D CAD program, one set by hand drawing. They had to be to scale, which means I had to properly measure things. The instructor graded the drawings for accuracy. For the clock I made the bridges, and I learned various ways to set the spacing of the pivots to ensure proper depthing of the wheels and learned the importance of positioning, which allows you to take it apart and put it back together and the pivot holes will be lined up properly every time. One of the pivot holes for example I had to do through math and triangulation only. So swinging arcs with a compass and placing a divot on that point and drilling a hole. I made the pillars for the bridges, one of the train wheels needed a new arbor to meet the endshake requirements of the bridges. I made the click, the dial, the hour markers, the hands, the hubs for the hands. And I made from scratch a Graham deadbeat escapement for the clock. So I made the escape wheel and the pallet and the pallet stones.
Once that project was finished I made a 3/4 bridge for a ETA 6497, and in my case the balance bridge as well. I learned about various ways to transfer holes from mainplate to bridge, turning recesses, boring holes for jewels. I can go on here as well.
I am not a master of micromechanics, but I learned a considerable amount. In the first year I also learned to service quartz watches and quartz theory. And I also learned to service basic automatic watches. The last portion of the first year was learning refinishing of cases and bracelets, the various wheels and compounds used to remove damage, maintain case shape and polish, or appropriate line finish and how to apply it.
The first year of school is fairly intense. There is far more than I mentioned.
Second year of school was dedicated to watchmaking theory and real life repairs and the service of the ETA 7750 chronograph. I learned to vibrate hairsprings, make overcoils, adjust hairspings in the flat and concentric coils. Adjustments. Regulations. Poising static and dynamic. Various calibers, adjusting hammers on vintage chronographs. Real life repairs included case repairs, maintaining water resistance, crystals and gaskets, case tubes and crowns. I bored out ovalized pivots and friction fit jewels in watches to make repairs, I burnished pivots. I wrote up job estimates for the repairs I did for approval. My work was not just focused on modern watches but also vintage... Again I can go on. The second year was just as intense, manipulating hairsprings is not easy work.
I successfully graduated from my school.
I currently have a SAWTA certification and a AWCI CW21 certification for watchmaking. I am level 40 certified with Jaeger LeCoultre. I am level 30 certified with Panerai. I am level 30 certified with IWC. I am level 40 certified with Cartier. I am a level 40 Rolex plaque account in my store. The industry recognizes my certifications, provides me brand and caliber specific training and allows me to perform warranty work on their products, sells me parts and they provide a brand warranty with my work, meaning if I service your watch and it has a warranty error, you can take it to them to be fixed under warranty, you don't have to come back to me. That is a high level of trust right? I started my career focusing on vintage service, before gaining the modern brand certifications.
So after writing my background in watchmaking I can say this. As I learned about Isochronism, rate independent of amplitude, I learned it was a lofty ideal not able to be fully realized. As example friction is an enemy of Isochronism, and you simply can not eliminate friction, so you always do your best to minimize friction.
In school in poising a wheel, I did not once ever move a screw to adjust for poise. Ever. Not static or dynamic. Moving screws is for changing the moment of inertia in a wheel. It does not eliminate a poise error as I understand. The mass of the screw is only moving further away from the center of mass or closer to it, but the poise error, which is a heavy spot in the wheel that can be pulled on by gravity in a vertical position is still there.
To have poise means that the mass of the wheel is evenly distributed around the circumference of the wheel in relation to the center of mass. It has no "heavy spot" for gravity to pull on in the vertical positions. As the wheel moves in the direction of gravity, it accelerates due to the influence of the heavy spot. As it moves away from the influence of gravity it slows down. This affects rate. Eliminate that heavy spot and the wheel has one less influence in the search for Isochronism, gravity being one of the enemies of Isochronism. I eliminate a heavy spot through poise, redistributing mass throughout the wheel, either by adding mass or subtracting mass on the rim of the balance, depending on the type of balance I am am working with, screw vs screwless, or position of the heavy spot, which screws are not always at the appropriate location.
I learned dynamic poising is necessary if after static poising I still have a poise error in the rate of the watch for the positions it is adjusted for during the timing phase of the service. I find the heavy spot by timing methods and I eliminate that heavy spot on the rim of the wheel.
There is much left unsaid here, as I am being extremely basic in my writing.
As moving screws is not a method I have ever used for poising, I can not comment on the effectiveness, and as you can see the methods I learned are different from what is accepted here.
Unfortunately I am not able to fully convey my understanding as I was taught. So I have to conclude with, the way I learned in school is the way that I service a watch, and I don't feel that it is wrong by any significant means. I believe someone said in this thread there is more than one way to skin something...
I will end with my passion in watches since becoming a watchmaker has focused on early watchmaking, as I enjoy all the many ways they overcome the enemies of Isochronism, or how they made advancements in technology. I am always carrying one of my various pocket watches in appreciation for what my Grandfather showed me when I was very young that lead me to this point today.
Welcome to the group. I received my Wostep Certification in Neuchatel. I know the Lititz program well. I used to host the class for a day at my home. It is a fine program.
In addition to my year at Wostep, I also took courses from Omega in Grenchen and special course taught by Tony Simonin on Precision Timing.
I think if you do some reading, you will see most recognized authors do not agree with you about the purpose of the screws on a bimetallic balance (Jendristki; Gibri, for example). They are there for rough timing and temperature and ultimately position adjustment.
I know well the exercise used to teach making up a balance complete with the vibrating, shaping, colleting and pinning a balance spring. And yes, when a new assembly is made, it is static poised. In fact after the course I sold my vibrating tool and spring material.
If you do not have the pattern for that particular watch, you are shooting the dark. And Tony told us how when he started at Omega it took him 3 months to produce a useable spring. For those who do not know, Tony Simonin was the designer for the Omega 561.
So I decided not to pretend I could make a spring for a precision watch from scratch. And simply making it tick is never my goal. The game is to return it to its original performance.
Now, what happens next in class? You fit your pride and joy balance assembly into your Eta movement right? Then you check positional rates, right? What do you do to correct the positional rates? You use the little cutter you made in class to remove material from the underside of the balance.
The goal of the game (and we considered it such) is to get as close a rate as possible with as few divots as possible.
Now, remove the balance spring and put it on your poising tool. No longer statically poised.
interestingly, many classes do not do this last step. Seems important to me.
The reason for this is that positional adjustments are used to counterbalance the natural escapement errors of the lever escapement. There are several; and I mentioned one, the asymmetric swing of the balance wheel. It travels further in one direction than the other.
If there were no other forces involved. then after static poising there would be no need for positional adjustments.
If you were not exposed to this area of timing, or you forgot, the recognized reference is Watch Adjustment by Jendritski. I understand it is the foundation text for that portion of the programs in all the Swiss schools.