As a business owner that runs an operation where every single job is different in some way its often quite hard to describe to people what we actually do. “We repair clocks” covers a huge amount of different jobs each with its own associated or individual method. So, its getting to the end of the week and I thought it might be interesting for you to hear the jobs so far and what we did. The following snippets are obviously not the entirety of what has been completed, started, put on the shelf , or picked up again with a new method in mind, but it gives an idea of what we really do. Ok….
Tissot Automatic Mechanical Watch repair
Bob came in with his Tissot. An nice 70’s auto with a gradient fade face in light brown on a gold case with a light leather strap. I wore it for 3 days on test (the only real way which you will have proven in this snippet) and I became quite fond of it.
The reason we were doing this watch is that we had taken on a very strange and exotic movement on for repair, carried that out successfully, and so Bob was coming back with a “no hope” job he had given up on but thought he may now have found somebody up to the job. Actually this sounds rather big headed but its what happened so what am I supposed to write?.
Anyway this watch had been through two high street jewellers and each time had come back unfixed. It ran 20 minutes fast a day. I was confident we could do it so I said “no problem” and got it fixed. The crown gear inside was broken and needed replacing so we sorted that out first. The watch underwent its basic service operations and ran correctly. We charged Bob a very fair price as a returning customer, which he appreciated and ticked it off the list – job done. A week later I got a somewhat annoyed phone call. Now, Bob is a nice guy, and apart from wanting to nuke China, is not in the least confrontational but it was obvious from the tired tone of his report that he felt let down and not entirely by surprise. The watch was running 20 minutes fast.
No. No. No. We have never had a watch back. So I obviously agreed to have it looked at as early as he could get it to me and we did just that. At first we had assumed oil had drifted onto the hair spring through a lubrication error. If oil gets on a hair spring in enough quantity it can form a bridge between concentric passes which has the effect of, from a physics point of view, shortening the spring. A shorter spring will result in a faster oscillation of the balance wheel. The faster the balance wheel cycles the faster the watch will run so it was an obvious assumption to make about the fault.
When the watch was opened there was no oil anywhere it shouldnt have been. We then found that the hair spring was very very slightly warped and close to its platform. If a hiarspring touches its platform mounting while in motion is has exactly the same effect as the oil. It shortens the operating lenght of the spring leadying to a higher BPM (beats per minute). The spring was remounted to be as far as possible from its supporting platform edges and that made the difference. I wore the watch, as I said, for three days. During that time I was half expecting it to run fast for some reason. It didnt and kept perfect time. We also fixed the date wheel advancement which Bob had simply assumed was impossible to fix as the previous repair efforts had not managed that, or possibly even bothered testing it because that part wasn’t a difficult fix.
What was bugging me was “why?”. You see, the watch had been tested the first time and it was running perfectly. It was only when Bob put it on that it started gaining time. At first my thoughts were towards an error in the winding system or gearing but then I had a Eureka moment. Its not that I know this is what was wrong with the watch, its just that its the obvious reason when you think about it, and here it is. HEAT. Bobs body heat when he wore the watch was slighty heating up the carbon steel hair spring. If you deform a hair spring at the beginning of its wind length this warp is exaggerated exponentially by the length of the spring because you are warping along the length of the spring not the diameter of the coil. The spring at room temperature was almost touching the platforms and it was, as sods law dictates, close enough so that any change on its axial level / flatness would bring the end of the spiring in contact with the platform.
Ironically because the connect would have been right at the edge of the coil the watch would still keep running but, for the already stated reason, run slightly fast. If the contact had been in the centre of the coil the watch probably wouldn’t have run and the problem discovered by the other two jewellers, but because I wore the watch I found the problem. Retrospectively of course but that doesnt matter. What is important is that next time it happens we know. Experience like that is money in the bank and better better better. I love better.
Cuckoo Clock previously repaired by a mathematician not an engineer.
Ok so another job this week worthy of mention was a simple two weight cuckoo clock that came in. The owner wanted the clock working but had a limited budget. I explained the pricing policy and range, how we could avoid certain costs, and what may become essential in order to complete the job. On occasions like this I take a bit of a commercial risk. I could see the movement was not standard in many ways, and worse than that there was no obvious reason why the clock should not run. I checked the connecting faces of all the wheel teeth and pinion gears with everything looking in great condition for a 50 year old clock. The bushes were nice and unworn, the gearing mostly clear of fouling, and the pallets in good order. I cleaned the clock on a full disassembly as my thinking was that with such a good condition fit for the bushes it must be oxidation on the inner bush walls. On cleaing and lubrication the clock turned over….but not…right. There is no real way of measuring how much torque an escapement cog is generating, its something you get a feel for after working on a lot of different movements. You recognise a healthy movement in the same way you might an animal. You can just tell, if you know what to look for, that you have a grand national winner or a beach donkey. This one was wearing a red had and carrying a small child jamming an ice cream in its face. So what could the problem be….I had to put this down for a day. I realised during the night what the problem was. The bushes were brilliant. For a 50 year old clock they were immacuate. Too immaculate. Too unworn.
I went in the next day an hour early just because I wanted to check out my theory. I was correct. The clock had been “b*&*^ered about with” by somebody playing “lets try and bush a clock”. It was a bad repair performed years earlier so the patination of the new parts had faded and was undetectable. When you fit a bush for the first time the target is to get a nice snug fit with the current pinion diameter that has worn down on the old bushes. You can overdo this. If you don’t know what sort of torque you should be seeing at the escapement end its going to be very easy to bush a clock so that the fit is a little too snug and doesn’t give the pinion any room for manoeuvre. It needs to have a bit of play in it because you are fitting a bush to a slightly worn pinion gear and wheel. This means the rotation forces are not directly central as when the wheel and pinion gear connect the can move closer and further away from each other during the rotation cycle. This means two things. Tight bushing of this type leads to a cyclic partial seizure in the rotation cycle. In short, the gears are pushed closer and further apart during the cycle. This normally manifests itself as stiffness or partial seizure during each turn at the same point, or at the same frequency depending on the ratio of the gearing. This wasn’t what was happening so I hadn’t spotted it. What had happened was that the pinion gears and wheels were in unworn condition but the clock was simply bushed two tightly on the second wheel. I started at the top and broached the bushes by a fraction of a fraction of a mm and it worked perfectly. Clock repairs are like this a lot of the time. The process of diagnosis is absolutely critical so its important to use methods that explore the configuration, lubrication, and cleaning of components before you create one brass filing. One mistake I made when I first started was that I was too keen and in too much of a hurry generally. I have learned over the years that you have to be focussed and confident with what you are doing. That confidence only comes from success which is the product of method. So before you do anything on a clock work out how you are gong to do it. Allow time for the things you MUST get right first time and if your frustrated with a diagnosis then admit defeat for the day and the high ground will come to you tomorrow. Your brain is working all the time and so if you have a logic problem you will often find the old grey matter will deliver given time and your then running down the street in a towel like Archimedes.
The secret is caring. If you don’t care you wont think about it. Incidentally, care is not the same thing as worry. Its easy to mistake one for the other if its a friends clock you are working on. If you find yourself getting out of your depth and are actually worried then just stop, give the job back, retire and regroup. You cant do that if youve physically changed the shape of any metal in any way which is why its important to understand what a big step it is on a job to make changes you cant come back from or get support on if you need it. Incidentally if you are reading this with your mother in laws clock in 200 bits that somebody “cleared up for you”, rather than divorce, ring me. Its cheaper. Marginally.
(A joke to far – our prices our excellent).
Thats one day of man hours. Quite a few. Clocking is not a fixed hours occupation if your doing other peoples cherished family heirlooms.
Ok. Had enough. Off to bed.
Recent Comments