 |
PM |  | |
Quote | | |
Reply | | |
Full Topic | |
| Joined: | Thu Dec 31st, 2009 |
| Location: | |
| Posts: | 146 |
| Status: |
Offline
|
deadlyapp wrote:The first question is easily answered, but without a very very fine force measuring device I can't tell you. It's on the scale of a hundredth of a Newton though I'm willing to bet.
You would know better than I, but with the very efficient gear trains in most modern watches, the force multiplier from the stem to the mainspring probably negates any change you might "feel" as feedback. Thats why most winding watches have some sort of clutch system - which may be as simple as a plate with a specific friction coefficient that will not grip the mainspring barrel once it reaches a certain preset.
Whew....I read this for 10 minutes and still couldn't get it. Thanks for the technical tidbit. I learned a lot.
Honestly I don't know crap about watches, but as a mechanical engineer I can kinda visualize some of it. Anything I know about watch movements I've read and the technical information in most articles is zilch. I'm relatively sure though that turning the stem does not directly turn the mainspring, it goes through several gears in order to exert more force, and then that force is transmitted back into a seperate gear train that runs the hands and timekeeping portion.
The force the spring exerts is simply a function of how much it has "deflected" - or been wound. As it becomes less wound the force it exerts is lower - which would affect the time keeping, hence why they use gears to manipulate it.
http://en.wikipedia.org/wiki/Mainspring
Edit: more about causing damage to the spring. I read through that wiki article (which is extremely good by the way), and as I said above, most autos already have some sort of clutch system in place that will sufficiently keep the watch from "overwinding"
With an older watch without such a system, you could in fact exert too much force - enough to possibly snap the mainspring or at least stretch it inelastically. You'd have to do a pretty detailed spring analysis though and know the metallurgy of the material in order to tell what that would be. You could make some educated guesses that would probably work though if you set the slip point low enough.
Last edited on Wed Jun 30th, 2010 01:45 am by deadlyapp