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vinn2
路I think, the wind gear ratios vary from watch to watch. ( note helbrose movement }. when they figured out how to eliminate stem - pre wind - they did it,! giving YOU "automatic wind". -- vinn
9300 Winding Question
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Archer
路路Omega Qualified WatchmakerHi Rob
I just saw this thread and scanned your and Al's comments without trying to follow them in detail but, "Hooke's law". My goodness, this is getting technical馃槻. I'll throw in Young's modulus (E) and tangent modulus (Et) just to muddy the waters further 馃槈 - hey, I'm on holiday now but still feel the need to write a few Engineering terms馃榾.
Enjoy your Christmas.
Cheers, Chris
Ha! Hooke's law - that is whole other can of worms to open with regards to mainsprings. Mainsprings are non-linear, and are not traditional torsion springs. For example in any calculation of force in a mainspring, you won't see length as a factor, where you would in a torsion spring. When you install a longer mainspring in a barrel, it does not increase the torque...I have had this debate with people before...
I think of a mainspring as more of a beam that is being bent through an angle, and the resistance to bending produces force/torque. That is a factor of the free length of mainspring that is active at any given time, and the width and cross section of the spring.
Cheers, Al
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Archer
路路Omega Qualified WatchmakerHi Al and Rob
You've written a lot here and I still didn't read it all but, a picture paints a thousand words. Took this picture from Christian's website:
It appears the auto barrel is the one on the right and the crown wheel is acting on the other barrel (not ratchet wheel. Aha, so this is how you make a two barrel watch!). Assuming both have no reserve at the start, it seems obvious unless I'm missing something?
So, once you turn barrel 1 (left hand), there is a torque on it's ratchet wheel because the spring inside wants to unwind. There's that intermediate ratchet wheel which is now suffering a torque and so, logically, barrel 2 (right barrel) ratchet wheel is as well. If so, then barrel 2 is being wound at the same time as barrel 1 (there must be a slight lag as there's a bit of friction to overcome so you need a little torque on barrel 1 ratchet to overcome that).
Surely, it's no more complex than that?
I assume the click is only on barrel 2? I also suppose that the second wheel is only connected to barrel 2?
Interesting, cheers, Chris
Edit: so, I read what you both wrote again.
I seem to have reproduced a lot of one of Al's posts but, hey, my stolen picture makes it clear馃槈
I think that what you're saying, Rob, would be true in an ideal world where the torque reaction of the mainsprings would be constant for any state of wind. But, if that was true, then why are my balance amplitudes lower at 24H than 0H? (Please, don't say it may be my poor oiling regime馃槜) Seriously, these mainspring designers aim for a constant torque release but it's not possible as you know. I make the auto barrel spring some 7% higher nominal strength than the fixed one. I bet that when the auto one is 50% wound, it's resistance is only equal to the fixed one at 49%. I think you know what I mean - A picture would help!
Hi Chris,
Yes I believe it is that simple.
The main sticking point for Rob seems to be the fact that he can't get past a weaker spring being able to wind a stronger spring. But as I've said, that is only true at the upper limit as Omega calls it. At any stage of winding before the upper limit, the torque in barrel one can be higher than in barrel 2, causing the spring in barrel 2 to start to wind.
Rob also seems to be equating my stating what Omega says, that the torque is the same between the barrels to me saying that the amount of turns would be the same, and of course I have never said that. That is why I've stuck with the term torque the whole time as it keeps things cleaner.
The actual number of turns required on the spring in barrel 1 to provide enough torque to start barrel 2 winding would be determined by the friction in the barrel assembly and resistance to bending of the spring in barrel 2. If a mainspring is coned, there is too little barrel arbor end shake, etc. can all play a part here, so it's not just the spring strength at play of course.
Anyway no time left as I'm off to run errands, but you have it figured out Chris.
Cheers, Al
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guelerct
路Totally unrelated question
But I was watching the excellent documentary Slingshot on Dean Kamen.
He builds clocks as a hobby and there is an amazing pendulum clock in his foyer. Has anyone seen this yet? And if so, what kind of clock is that?
But I was watching the excellent documentary Slingshot on Dean Kamen.
He builds clocks as a hobby and there is an amazing pendulum clock in his foyer. Has anyone seen this yet? And if so, what kind of clock is that?
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vinn2
路has anyone worked with a "LIFETIME MAIN SPRING" ? I bought an elgin RR pocket watch that was very hard to wind. upon taking it apart to clean and when opening the barrel --- KAR OOM ! out it sprang. well; merry christmass to all
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Archer
路路Omega Qualified WatchmakerJust a follow-up on this subject as I had emailed the head trainer at Swatch in NJ when we were discussing this, but he was away on vacation. He just got back and confirmed that both barrels wind at the same time once the first one builds some torque...
"During winding, barrel #1 鈥榮 mainspring coils inside the barrel applying torque to the barrel arbor. The torque applied to the arbor is transferred through barrel #1鈥檚 ratchet wheel to the ratchet transmission wheel then on to barrel #2鈥檚 ratchet wheel. When the torque applied by mainspring # 1 is great enough, it will wind the mainspring in barrel #2 (automatic mainspring) by the barrel arbor in the traditional manner. In this way both mainsprings wind together as you noted. "
Cheers, Al
"During winding, barrel #1 鈥榮 mainspring coils inside the barrel applying torque to the barrel arbor. The torque applied to the arbor is transferred through barrel #1鈥檚 ratchet wheel to the ratchet transmission wheel then on to barrel #2鈥檚 ratchet wheel. When the torque applied by mainspring # 1 is great enough, it will wind the mainspring in barrel #2 (automatic mainspring) by the barrel arbor in the traditional manner. In this way both mainsprings wind together as you noted. "
Cheers, Al
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ms13rch10
路I hope this is sufficiently on-topic. Having just acquired a couple of Seamaster Planet Ocean models, one used, one new - calibres 8605 and 8906 - I am slightly confused about manual winding. On my old Speedmaster manual-wind, there is tangible feedback when approaching the point where the spring is fully wound. I have not encountered anything like that with these Seamasters, and am concerned about how much winding is possible / permissible. I realize that only a modest amount is necessary before wearing the watch, but I am curious about this. Perhaps it's because these movements with two barrels have a much longer reserve, and I tire before reaching capacity. Or... ? Thanks in advance. [how many turns before fully wound?]
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Archer
路路Omega Qualified WatchmakerI hope this is sufficiently on-topic. Having just acquired a couple of Seamaster Planet Ocean models, one used, one new - calibres 8605 and 8906 - I am slightly confused about manual winding. On my old Speedmaster manual-wind, there is tangible feedback when approaching the point where the spring is fully wound. I have not encountered anything like that with these Seamasters, and am concerned about how much winding is possible / permissible. I realize that only a modest amount is necessary before wearing the watch, but I am curious about this. Perhaps it's because these movements with two barrels have a much longer reserve, and I tire before reaching capacity. Or... ? Thanks in advance. [how many turns before fully wound?]
Generally automatic winding watches can typically be wound forever - there is no hard stop like there is on a manual wind, because one end of the mainspring is not attached to the barrel, so it can spin around in there as long as you continue to wind.
In the case of the Omegas with two mainspring barrels, one spring is fixed to the barrel at both ends, but the other is free to wind forever with one end loose. Again the result is that this watch can be wound virtually forever without ever coming to a hard stop.
Cheers, Al
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