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Thread: Miyota 9039 winding via crown question

  1. #1
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    Miyota 9039 winding via crown question

    Noticed since letting my PRS-47 stop while giving another watch wrist time then restarting it, the loss of time per day has increased from its initial -5 to -8 seconds per day to -13 plus, which I believe is more than the manufacturers specification for the Miyota 9039.

    However I've read this is measured from a full wind via the crown but on giving the crown a carful wind I've not been able to establish what a full wind is. Apart from the usual gritty feeling the resistance to winding doesn't seem to change, so stopped before I broke it.

    Anybody any advice/thoughts?

  2. #2
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    Quote Originally Posted by Ed875 View Post
    Noticed since letting my PRS-47 stop while giving another watch wrist time then restarting it, the loss of time per day has increased from its initial -5 to -8 seconds per day to -13 plus, which I believe is more than the manufacturers specification for the Miyota 9039.

    However I've read this is measured from a full wind via the crown but on giving the crown a carful wind I've not been able to establish what a full wind is. Apart from the usual gritty feeling the resistance to winding doesn't seem to change, so stopped before I broke it.

    Anybody any advice/thoughts?
    To clarify, thereís no obvious point at which youíll know an automatic watch is fully wound. When this condition is reached the mainspring will slide around the inside wall of the barrel so its impossible to do damage. Sometimes this can be felt through the crown, especially if the barrel wall has cut- outs to allow the spring to slide in controlled increments. On the Miyota its hard to detect any change, but if you give the crown 55 twists itíll be fully wound, Iíve worked on a few and thatís what it takes to fully wind them.

    If youíre wearing the watch in a low state of wind the timekeeping will deviate significantly from what you expect, the amplitude will be too low to get into the region where the watch behaves as it should.

  3. #3
    They tend to keep better time on the wrist rather than sitting on a desk, that's my experience anyway.

  4. #4
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    Quote Originally Posted by TheFixer View Post
    They tend to keep better time on the wrist rather than sitting on a desk, that's my experience anyway.
    Thatís consistent with keeping the movement in a high state of wind. When timing and regulating watches I use the Ď dial upí data but I only measure the rate over a period of 10 hrs after knowing the watch was fully wound.

  5. #5
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    Thanks for the responses appreciated.

    Wound the watch around 20/25 twists on both occasions I've started it from stop and my on wrist time watches tend to get worn throughout the day and sometimes through the night too if I forget to remove it before going to sleep.

    As I just wound it probably 30 to 40 twists I'll see how it goes over the next 24 hours, hopefully back within limits.

  6. #6
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    Quote Originally Posted by Ed875 View Post
    Thanks for the responses appreciated.

    Wound the watch around 20/25 twists on both occasions I've started it from stop and my on wrist time watches tend to get worn throughout the day and sometimes through the night too if I forget to remove it before going to sleep.

    As I just wound it probably 30 to 40 twists I'll see how it goes over the next 24 hours, hopefully back within limits.
    I have plenty if experience with these movements, strongly recommend you give it 60 twists and be sure youíre starting with it fully wound. I also recommend not wearing overnight, leave it dial - up and youíll get better consistency. Record the rate on the wrist over approx 16 hrs, record the 8 hrs dial up overnight, and see what the numbers tell you.

  7. #7
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    Quote Originally Posted by walkerwek1958 View Post
    I have plenty if experience with these movements, strongly recommend you give it 60 twists and be sure youíre starting with it fully wound. I also recommend not wearing overnight, leave it dial - up and youíll get better consistency. Record the rate on the wrist over approx 16 hrs, record the 8 hrs dial up overnight, and see what the numbers tell you.
    Thanks will give that a go and since giving it a good wind yesterday its back within tolerance again, lost around 5 seconds.

  8. #8
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    Quote Originally Posted by walkerwek1958 View Post
    I have plenty if experience with these movements, strongly recommend you give it 60 twists and be sure you’re starting with it fully wound. I also recommend not wearing overnight, leave it dial - up and you’ll get better consistency. Record the rate on the wrist over approx 16 hrs, record the 8 hrs dial up overnight, and see what the numbers tell you.
    After two days of monitoring and remembering not to wear it at night its lost 2 seconds, though today I've been at work so using a civilian issue CWC G10, therefore the Commando has been sat on the side for a good part of the day and it seems to have lost most of those two seconds during this period of inactivity.

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