We work by standards and laws that sit universally in the bedrock of engineering. Clocks for me are by far the best obsession for the determined fiddler solving a puzzle where all your variables have to be defined by theory and observational diagnosis. Across multiple scientific disciplines that overlap. Not easy and sometimes, within the process the diagnosis is as simple as “ “that is most definitely an *NFG bin job – replace that”. On most other occasions its somewhat more complicated.
*NFG [acronym in common use by technical engineers for identifying boxes containing stored failed components. If you ever see a boxed item with NFG in biro on it, you can assume the goods are Not F……..ulsomely Good]
You have to visually apply formulas as known constants and understand they describe ratios not theories. You have to have working knowledge of the geometry principles for calculating linear and arc distances including torque metrics and direction. Its important to know chemistry because if you put the wrong reactive chemical on the worn surface you have to be bloody good at recreating a seamless and invisible covering. So Art in its Aritisan format . This might be enamel, brass alloy, oil pants, water based paints, laquers and the compatibility of all these things is often an issue that needs a process to overcome.
You cant lean it from books because there are so many combinations. You actually need a broad education or interest at a detailed level in the physical and theoretical sciences. Not sub quantum physics, it is incidental to clocks but not an essential part of the engineering education process.
Its all newton pi pythagoras and torque on clocks.
That said molecules and chemistry comes into it. You cant silver a dial without knowing about the piezoelectric effect. You cant understand carbon steel metal fatigue in springs and check for it unless you understand its arrangement and composition at an atomic level. Once you know that, its easy to spot the amplified effect of this on the physical condition of the steel.
This degradation at different parts of the spring due to its usage on rewinds. This varies. Some parts of a spring may have been wound more frequently that others. This is likely. Many clock owners wind their clocks erratically. This means the top of the springs gets wound and bent more often that the top of the spring. Its the laws of averages reaching a human habitual nexus. Unavoidable for 99|%.. To really evaluate an original spring in a good old clock you have to use a method that incorporates that tests for variable fade. Half the spring may be fine and acceptable for occasional use.
The molecular degradation also matters because a springs resistance power increases exponentially with deformation so the centre end of a spring is far more likely to be the point of failure but Ive seen them snap halfway through. At any rate a lot off energy gets released in a very particular way which I will come to.
Most springs do not fail because they have been overstretched. They fail because the molecular bonding that allows their elsaticy breaks atomic bond, by atomic bond over time. This breakage is more prevalent around seams of carbon that are mixed into it to provide a sort of spongy elasticity. Seams of weakness are seeded, connect as they randomly expand, form fractures and integrity fails with a bang and a clock bill.
Unfortunately it usually doesnt stop after the bang. Another thing can happen in that bang, which is an age in the time it takes different forces to build up and release together. Read on.
What then happens is in classic Newtonian format. The conservation of energy is applied. So why is this important or relavent?. Well its because Newton tells us most wisely that we have angular conservation of momentum. We also know from Newton that energy is conserved and tranferred by physical or electromagnetic radiation. On this we are talking physical energy. Kinetic (moving energy – the faster something hits you the more it hursts – more energy), and potential energy (the energy you have to use to get an object from still to moving). To work out how much energy is transferred by the spring break you take the amount of torque energy generated at a tangent to the centre i.e. onto a severly geared down second pinion (a small cog with thick teeth equivalent in circular distribution distance to those on the larger cog – huge torque join).
Ill just do the basic maths here of how much power is tranferred in one go. So you take torque normally generated had he spring been unfurled over time. So thats all the energy it would have taken to keep the pendulum swinging for say 2 days. The velocity issue here is to do with the fact that there will be some give in the gear train when the spring snaps to dampen the shock. But this is a questionable damping force because it allows he momentum of he mass of he whole cogg drum to come into play. So now as well as 2 days operational torque being delivered in a fraction of a second, you have a fraction of a second for the mass of the brass spring barrel in which to rotate very very quickl under huge accelleration force. The amount it moves may be small but the punch it packs when it tranfers its force is disproportionate to the assumptions one might make. In short this means his means Newton again. Force = mass x acceleration applied to the barrel mass in addition to the torgque force created in an instant.
Its outrageous proportional acceleration making the momentum impact force of the cogg teeth quite high all things considered despite its modest scale. The result is that the teeth get stripped from the main barrel like corn under a crop circle UFO. The teeth fold down. Attempting reformation is more like miraculous resurrection. You have to find a way to get a new one, either old spares or make one or talk to your god. We have it covered however.
If I’m just speaking gibberish to you I apologise. The result of all this explanation is that you now know that when a spring snaps there is about a 50/50 chance you may need a new barrel. Some are available spares, some are still made, most old ones have to he lathed out and wheel cut which is a fortune.
For me this is just a fact of life but for you, well, if you got this far you must have at least found it interesting. I really enjoy explaining things in an accessible way but I feel I may have pushed the envelope on this one and if I have bored you I apologise.
We are busy doing all this stuff and I just dont get the time to pass on my work examples or self help or comment posts. Im probably going to do more theoretical and background stuff rather than practical stuff from now on, but even in he article above is an awareness issue which in itself is a contribution to the knowledge base generally.
When I look a the considerable things we have achieved I am reminded that my skills are modest in comparison to the makers of some of the clocks I work on. Challenges are contemporary and have different meanings in different times.
Take the statue of Liberty. Made at the same time as many of the clocks we work on and repair. No boast-able moving parts. I would not have liked to be the engineering specifier on that one.
architect talking to structural engineer: “How thick does the copper have to be on the arm plate bearing in mind it might get hit by a tornado. Shutup. We also dont want the arm to fall into the Hudson due to overweight, and we want to save money on copper. Don’t forget to factor in the three laws of thermodynamics and futurise [made up management word] how this will effect the structural tension of a copper balloon welded round an iron hedgehog holding a Cornetto”.
Oh we repair a lot of cuckoo clocks as well. I just like them and do most of them. We have spares and manufacturer accreditation for the UK.
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