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Math with Time

by Jordan Ficklin

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I sometimes have to deal with a watch company which I won’t name (it’s not Rolex) that has trouble with their customer service. On a recent occasion I was told that despite their invoice stating that case refinishing was a part of their full service they were unable to refinish a certain style of bezel. They made the watch, but they can’t refinish it. Oops! Sounds like a major design flaw to me. One of the reason watchmakers love Rolex is because they are so serviceable. They are serviceable because Rolex thinks about after sales service when they create their models.

This week I received another watch back from having been serviced by them and it had gained a significant amount of time so I put it on the timing machine. It appeared to be running about 15 seconds per day fast. Friday afternoon I put it on the Final Test (rotating simulator wheel) and Monday morning it had gained 37 seconds. That translates to about 15 seconds per day. I called them up and asked them if that was acceptable for their product. I was informed that they try and have their watches running within 2 minutes per month (COSC specs) but that they allowed up to 5.5 minutes per month. Ouch! That’s an hour a year. He said that 15 seconds a day was only about 4 1/2 minutes per month so it was an acceptable error. Say what? 15 seconds per day is 4 1/2 minutes a month? Let’s do the math:

15 seconds times 30 days is 450 seconds –> That must be 4 and 1/2 minutes. Well, maybe this guy thought there were 100 seconds in a minute, there aren’t. 450 seconds is 7 minutes and 30 seconds. Needless to say I’ll probably be having to regulate this watch since that apparently isn’t part of a full service either. — P.S. I did the above math in my head. But for the benefit of the guy on the other end of the phone here is how you add time on a calculator:

To add time with the calculator the easiest way is to use a scientific calculator which will do math in degrees, usually indicated by a button marked DEG or ? ‘ “. The degrees, minutes, and seconds are divided into 360, 60, and 60 segments respectively and work well for time math up to 360 hours. If you don’t have a calculator which will compute in degrees you can use another method. When adding two times together input the time in the form hhmmss. each time the seconds are bigger than 60 add an additional 40. Each time the minutes surpass 60 add an additional 4000. Example: 1hr23min14sec plus 2hr40min50sec. Add: 12314 + 24050 = 36364 then add 40 because the result has more than 60 seconds to get 36404 and 4000 because the minutes are more than 60 as well to get 40404 or 4 hr 40 min and 4 seconds. It works the opposite for subtraction. Multiplication and division are more difficult. I usually convert everything to seconds perform the multiplication or division and then divide the result be the right factor to get minutes. That would 60 for minutes and seconds, not 100 and 24 for hours.

Still having problems, try one of many, many time calculators on the internet. Just google “time calculator.”

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One Comment

  1. Alex
    Posted October 31, 2008 at 3:48 pm | Permalink

    Thanks for the tip.

    I’m getting into watchmaking (on my own) and I always like reading this and some of the blogs you link to.

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