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Comment by Prcmaker | Hacker News Reader

I've been using the same mechanical watch, more or less every day, for a little over 12yrs now. Miyota movement, stainless body, Sapphire window, about $300. In years of machine shop work the movement survived fine, and has one scratch on window from some tungsten carbide.

Has kept brilliant time, maybe a minute a month, and taught me that my watch being accurate to the second was something that, for me, just didn't matter. I started working around pulsed high voltage last year (100kV+) and now it loses a couple minutes a week.

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> one scratch on window from some tungsten carbide.

Checks out. Tungsten Carbide and Corundum (sapphire watch crystals, the hardest watch crystal in use) have the same Mohs hardness of 9 and will scratch each other.

And I'd guess that a $300 watch probably doesn't use Corundum but rather mineral glass.

Lot of microbrands offer sapphire glass and very decent Miyota or Seiko automatic movements for $300-$500. Prices have crept up the last few years.

Orient has a few automatic models (Kamasu, etc) that can be had for under $300 with sapphire.

County comm mid pilot watch, it's advertised as Sapphire. Comparing with colleagues at the time, it was a far sight tougher than their watches.

I’ve got a cheap Seiko 5, the SNK809. Bought for $50 new in 2013, wore it for a few years then it moved with me in drawers for the past 5. I pulled it out last week, wound it up and it works perfectly, gaining just 4 seconds a day.

> I started working around pulsed high voltage last year (100kV+) and now it loses a couple minutes a week.

There are antimagnetic watches. Or you can use a cheap watch demagnetizer.

A demagnetizer is on the shopping list, but at the same time, a quick adjustment every now and then is easy enough. I also love my watch, so a switch to antimagnetic isn't high on my priorities.

> I started working around pulsed high voltage last year (100kV+) and now it loses a couple minutes a week.

Are these two things somehow related to one another?

Watch movements are generally sensitive to magnetic fields, and can become magnetized and lose accuracy. Some watch models explicitly advertise their level of resistance to magnetism, for instance the Rolex Milgauss, which is designed to withstand 1,000 ("mille") gauss.

Omega has watches that are METAS certified, so they resist up to 15000 gauss. They use silicon balance and silicon escapement.

Yes indeed, though not necessarily the cause in this case. While it could be coincidence, magnetization of components can result in reduced accuracy. Some companies have started to release watches with silicon springs, though very expensive.

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