Hamilton H21 Accuracy. "Long" term review.
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  1. #1
    Member DaveTOG's Avatar
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    Hamilton H21 Accuracy. "Long" term review.

    I purchased my Khaki King Field Chrono with the Hamilton H21 movement back in June. I know not that long, but hey...


    Attachment 1897258

    It has been my primary watch, and as close to an everyday wearer that I have. I wanted to give a quick "long" term review of the accuracy of the H21 movement.

    First some info on the H21 for those that don't know.

    From the Hamilton website.

    The Hamilton H-31 and H-21 are based on the chronograph Valjoux movements 7753 and 7750. Four elements have been modified:

    - The spiral has been glittered to increase accuracy and stability.
    - The main spring has been improved to increase a typical power reserve of 60 hours.
    - The automatic device bridge has been modified to offer decorative possibilities for personalization to the brand.
    - Customized balance bridge with Hamilton H-pattern


    Dimensions
    Caliber H-21 / H-31
    Size 13 ¼ lines (Ø 30mm) - height 7.90mm
    H-21: Hours, Minutes, Second*
    Chronograph: Hours*, Minutes, Seconds.
    Weekday and date following version
    -

    H-31: Hours, Minutes, Second*
    Chronograph: Hours*, Minutes, Seconds.
    Date setting by quick corrector at 10 o'clock

    My watch is the version with no second hand.
    (borrowed pic)

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    That said, it takes awhile to really be able to judge the accuracy, however as the Chronograph is set up for 1/5 of a second, it gets to be easier. Back to that in a minute.

    First, lets talk the 60 hour power reserve.
    Once fully "charged" after 2 weeks of wear, I took the watch off and tested this. It lasted just under 64 hours. 2 weeks later I tried again, and it lasted just over 65 hours. I really should try one more time so that I can average it, however I hate going that long without wearing it. Let's just say that the claim of 60 hours appears to be on the low end, at least for me.


    Back to the accuracy.

    Out of the box I seemed to be gaining about a minute and a half a week. Doing my best to judge it by running the chrono full time for a couple of days, I was about +12. Knowing that a typical Valjoux 7750 with basic Standard Grade should be +/- 12 seconds a day.

    Now it is my understanding that Hamilton never uses below Elaboré grade for any of their movements. Which should put us closer to +/- 7 seconds AND they say above the H21 is a 7750 that has been modified and the "Spiral has been Glittered to increase accuracy and stability" Whatever that means. I would expect closer to "Top Grade" and give me closer to +/- 4 seconds.

    I gave it a standard "Break In" period of just over a month. The numbers never changed. Soooo off to my "watch guy" to get it regulated. My guy threw it on his machine, confirmed a +11. So 2 days and $38.00 later I picked it up. He boasted that I should be to +/- 1 "or so" the guy is good, but let's face it, only as good as the movement he has to work with.

    That was 3 months ago. Since then, I have worn the watch on the average 5 days a week, and it is in a winder when I am not wearing it. In this three months I check the the accuracy via Time.gov every Saturday. Here are the last 13 week results.

    1. 0
    2 -1
    3. 0
    4. +2
    5. -1
    6. 0
    7. +1
    8 -1
    9. +.5
    10. -1
    11. +1
    12 -2
    13 0


    By my count -1.5 seconds in 13 weeks. Not bad for a watch you can pick for about $1000.00. Or any watch for that matter.

    Plus it looks great! Here it is on an after market Panatime leather strap!

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    I will try to remember to give another update in a few months.
    wwarren and cadeallaw like this.
    Time is relative.


  2. #2
    Member hchj's Avatar
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    Re: Hamilton H21 Accuracy. "Long" term review.

    Thanks for the detailed report! I used to own a H21 powered X-patrol. It did +7s per day out of box.
    Ball, Breitling, Omega, Rolex, Tag Heuer and Titoni











  3. #3
    Member Robotaz's Avatar
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    Re: Hamilton H21 Accuracy. "Long" term review.

    Wow! Amazing.
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    2. I own everything that I post and paid for it with my own money.
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  4. #4
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    Re: Hamilton H21 Accuracy. "Long" term review.

    Are the better made as compared to the Valjoux 7750/3

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