[time-nuts] Measuring the accurcy of a wrist watch

[Bob Albert]

Yes, magnetic fields mess up mechanical watches.  My dad was a watchmaker and found the need to demagnetize all the watches he worked on.  The hairspring was the  most sensitive part, and the coils would stick together if magnetized, and the watch would run very fast.


Bob

On Thursday, April 17, 2014 9:06 PM, DaveH <info at blackmountainforge.com> wrote:
 
I remember growing up (50 years ago) that the good watches were marked as
being non-magnetic.  I would guess that this is standard now.

My concern is that the moving balance wheel could have an eddy current
induced into it and the resulting magnetic field might cause it to slow
down.

http://en.wikipedia.org/wiki/Balance_wheel

http://en.wikipedia.org/wiki/Eddy_current

The act of measurement should not cause a change in what you are measuring.

Dave

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Chris Albertson
> Sent: Thursday, April 17, 2014 17:12
> To: Claude Fender; Discussion of precise time and frequency 
> measurement
> Subject: Re: [time-nuts] Measuring the accurcy of a wrist watch
> 
> Are watches damaged by magnets?  I hope not because magnets 
> are common.
> Yes a guitar does have some powerful Alnico magnets in the coil.
> 
> If this were a problem I think we would have heard about it.  
> My guess is
> that watch parts are non-magnets brass and stainless and 
> glass and so on.
>  Not plain steel or iron.  But maybe there are cheap watches made with
> stamped steel part?   I don't know.
> 
> In any case my experiment of placing the watch nest to the 
> pickup caused no
> damage.  Next time I get a chance I'll haul the guitar over to the HP
> counter and see if I can't measure the watch tick period.
> 
> 
> Something to consider is that most pickups are biased with a 
> fairly strong
> > magnetic field.
> >
> > Don't know if this would cause any damage or changes in 
> operation of a
> > mechanical watch but something to consider...
> >
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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