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    • Hi Everyone!  I have been practicing watch servicing these past months. So far I have successfully serviced a ST36 (ETA6497 clone), thanks to Mark's watch repair course which is awesome! I have also tried to service a NH25A, and messed up the hairpsring (replacement on the way), and a Miyota 8215. Everything was going well with the 8215 until I reassembled the train bridge and noticed that the escape wheel wobbles when I turn the wheels. My guess is that I accidentally broke off the upper pivot during cleaning. I was looking for a replacement escape wheel and found it at Cousin's, but they are out of stock. Anyone know any other place I could get one? Thanks.  PS: Trying to keep a positive attitude after messing up two movements, but practice makes perfect. :)  
    • Don't think of it as math so much as relationships. F=KX is (F) Force equals (K) spring k/constant times (X) displacement. You're only really worried with how they relate to each other, not anything more precise. If you multiply numbers together, the result is bigger; if you divide them, the result is smaller. If you want to isolate one of multiplied numbers, you divide the single figure by the other (i.e. K = F/X or X = F/K). The end. Force is exactly what you think it is. Displacement is a fancy word for distance. The spring k/constant is how stiff the spring is. For watchmakers, the important part here is that we can split apart the mainspring into component parts of stiffness (*) and distance (effective length; effective, because it's typically preferred that a spring is never fully wound or unwound for better isochronism). * Stiffness in a mainspring is typically a function of its thickness, but if you have a really old coil mainspring vs a modern S spring, or an old school spring steel vs a modern alloy, or maybe the spring has set, these can all play a part. The gear ratios in a gear train are fixed. For every release of the escapement, a certain degree of rotation of the mainspring barrel is unwound from the mainspring. That makes analysis even easier, because X is constant per beat. You simply get more X with a longer spring in the form of more beats. Assuming everything else is in proper fettle, you have a finite amount of room in the mainspring barrel into which you can stuff a spring. That stuffing happens across the dimensions of length, and thickness; dimensions that correspond directly with X and K respectively. If it's too strong, the balance over banks, and you gotta problem. EDIT: To a lesser degree, if your amplitude is higher than is required for isochronism, it's really not doing you any good, and is just a waste of spring. Too weak, and amplitude is low, and error creeps in (anisochronism). So you need a spring that is stiff enough to get you a good enough amplitude to ensure isochrony, but otherwise as long as you can to maximize power reserve. If everything else is good save that you have a new mainspring which feels noticeably harder and measures .007 thicker and feels harder (aka stiffer) and is .05 shorter, that's the precise recipe, according to Hooke's law, for a good amplitude but short power reserve. The answer, again assuming my understanding is correct and theory (which is all I have to work with so far) doesn't always mesh precisely with practice, is that a mainspring that is thinner and longer would solve your problem. The key assumption I'm making here, lacking the particular datum, is that the "good amplitude" is really good, and could stand to be a little lower. 312° is a really, really high amplitude; probably higher than just about any manufacturer requires for isochronistic reasons... On top of that, It sounds like Citizen kinda sucks for documentation, but they seem to be in the same school as Seiko who is good with documentation and is known for preferring unusually low amplitudes and still achieving reasonable isochronism. Given that the point of a high amplitude is to mitigate anisochrony, they're going at the isochronism problem from a different angle (whatever that is, I don't know yet). I would shoot for a typical Seiko level amplitude, see how the power reserve comes out, then check isochronism against your preferred/available of spec or personal standards. This has nothing to do with braking grease, internal barrel features, bridle wear or anything else. Just the isolated variables as described. Also worth noting, this is how Roger Smith (George Daniels' protegé) chooses mainsprings for his highly esteemed movements according to... him in his own lectures, and if it's good enough for Roger Smith... Also also worth noting... I'm about as nooby a noob that ever noobed, so consider the entire manifesto above in that light.
    • yep, they are not easy to come by.  
    • Main spring cleaning depends upon whose literature you're looking at. For instance Omega has a technical document on recycling mainspring barrels as they call it. They only wiped the mainspring down with a cloth no cleaners Or solvents. They're assuming that it Is a original mainsprings still has the dry somewhat invisible lubricant on its and that's why they just wipe it. At least that's what I'm assuming because there really really clear on no solvents were cleaners. If I'm doing a watch which is typically is a pocket watch and if I'm going to reuse the mainspring because it's an really beautiful nice condition then I just wipe it with a cloth with a solvent because it usually has sticky grease on it.  So I typically never clean mainsprings in the ultrasonic.   If the mainspring is an original blued steel spring Hulk still clean those with a cloth in a solvent but once their clean it put a thin coating of oil and/or grease on them. The Elgin watch company had a interesting document to why mainsprings break and they implied micro fractures due to rust. I tend to think poor manufacturing skills or not understanding things but steel mainsprings definitely do not like rust.
    • I think memory is less important than understanding. If you understand what the part does, then you should be able to figure out where it goes. Having said that, taking notes and pictures will help, both with the understanding, as you learn, and with those situations where it is less than obvious what goes where.  I recently took apart a Sekonda with date complication. I've taken apart and re-assembled several of these recently, and every time I do so, I can't for the life of me remember which way round one of the springs goes. I'm not sure what this proves, maybe Its an age thing, or maybe, and more likely, its because I don't actually remember every part of every movement, but actually figure most of it out based on experience. As it happens I also have pictures of that particular movement, and there are others on line, so the issue doesn't cause me any grief. If you have any doubt about a particular assembly or disassembly step. Stop and think.You will save yourself a lot of time in the long run, if you take the time to think. If you can't figure it out, ask. There are no daft questions, but there are many  people too daft to ask questions.
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