Sudden slight drop in accuracy -SD43, Slightly magnetized

[Otaru1987]

I’ve had my SD43 for a year and in that time it consistently ran -.7sec a day. No matter what position I placed it at night it was consistently-.7 sec a day. Two weeks ago it just suddenly dropped to -2.7 sec a day. I know most people will say that is fine but it is now getting out of spec and do not want it to drop anymore. Watch has not been dropped etc. I held it next to a small compass and shows to be very slightly magnetized. Could the slight magnetization have a influence on the wheels/gears to slow it? I know the hairspring/balance wheel are anti- magnetic. Any thoughts?

[SearChart]

It is a mechanical watch, its accuracy can vary. It is not magnetised.

[padi56]

Originally Posted by Otaru1987

I’ve had my SD43 for a year and in that time it consistently ran -.7sec a day. No matter what position I placed it at night it was consistently-.7 sec a day. Two weeks ago it just suddenly dropped to -2.7 sec a day. I know most people will say that is fine but it is now getting out of spec and do not want it to drop anymore. Watch has not been dropped etc. I held it next to a small compass and shows to be very slightly magnetized. Could the slight magnetization have a influence on the wheels/gears to slow it? I know the hairspring/balance wheel are anti- magnetic. Any thoughts?

Rolex watches are made mainly from S.steel or precious metals and in conjunction with nickel, brass or beryllium, bronze or Glucydur balance wheels so they are very anti-magnetic to begin.Although the main culprit that's affected is the hairspring causing it to stick,but in general when any movement is magnetised they speed up and not slow down your watch is not magnetised.Many things affect mechanical movements seeing the movement is constantly affected by the earth's gravity when worn or at rest.Plus things like metal expansion and contraction,different temperature variations, subtle changes in jewel lubrication and friction, shocks,mainspring power-reserve and so on.The fact is that no mechanical watch made will keep 100% perfect time, very close yes but perfect no.

[bradyb]

Hi Bas - do you know the percentage of watches that come in for service that are running fast and are, in fact, magnetized? Just curious as I would think it would be fairly high.

[SearChart]

Originally Posted by bradyb

Hi Bas - do you know the percentage of watches that come in for service that are running fast and are, in fact, magnetized? Just curious as I would think it would be fairly high.

Actually it's not that common for a Rolex to get magnetized (especially modern ones), maybe 1 in 25 orso.

[Bigblu10]

The parachrome hairspring in your watch is anti-magnetic, OP. Most likely not magnetized.

[SearChart]

Originally Posted by padi56

but in general when any movement is magnetised they speed up and not slow down.

Yep, the 'sticking' hairspring shortens it's effective length thus speeding it up rapidly.