seem to get a better wind with bumper movt???
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  1. #1
    Member lp1974's Avatar
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    seem to get a better wind with bumper movt???

    i recently started wearing a few bumper again. obviously vintage.
    it seems that bumpers wind "naturally" better then 360 rotor??! i realised i did not
    need to wind as much even though its the same 40 hr reserve.

    so i did a simple experiment with a watch winder and mounted a bumper (open cased and
    reversed) and a modern rotor (display case version, reversed mounted)

    i noticed because of how limited the angles for bumper , they do a consistent 180-200 degree
    ticktock swing. while the modern rotor would sometimes get caught in "suspended animation"
    with no winding motion. this is most obvious in directional changes.

    when i sped up the rotation to simulate typical human hand movement, with quick directional
    changes, the modern rotor were caught in a lot more suspended mode.
    interesting...

  2. #2
    Member HOROLOGIST007's Avatar
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    Re: seem to get a better wind with bumper movt???

    Yes. and Hans Wilsdorf claimed 'bumper' as an inadequate and useless design.
    NEVER ARGUE WITH AN IDIOT. FIRST THEY WILL DRAG YOU DOWN TO THEIR LEVEL. THEN, THEY WILL BEAT YOU WITH EXPERIENCE.

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    Re: seem to get a better wind with bumper movt???

    Name:  P7113836.jpg
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    This is a bumper right?

    Don't you need to have that arm really moving to make it work well?

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  5. #4
    Member HOROLOGIST007's Avatar
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    Re: seem to get a better wind with bumper movt???

    Quote Originally Posted by Shum View Post
    Name:  P7113836.jpg
Views: 138
Size:  155.0 KB
    This is a bumper right?

    Don't you need to have that arm really moving to make it work well?
    Yes this is a bumper movement. Swinging over only 270 degrees compared to Rotar that is 360 degrees.

    Regards
    adam
    NEVER ARGUE WITH AN IDIOT. FIRST THEY WILL DRAG YOU DOWN TO THEIR LEVEL. THEN, THEY WILL BEAT YOU WITH EXPERIENCE.

    "Failure is not an option" - Gene Kranz
    "Owning a vintage watch is great, understanding where it sits in Horology is magnificent"
    and
    "By Teaching Others, We Teach Ourselves"
    Adam

  6. #5
    Vint. Forum Co-Moderator Mirius's Avatar
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    Re: seem to get a better wind with bumper movt???

    Rotor movement isn't the only factor - whether it winds in only one direction or both greatly affects the efficiency. This applies to many early bumpers and rotors. A rotor that 'hangs' frequently can in fact still outperform a uni winding bumper.
    Last edited by Mirius; July 11th, 2013 at 10:57.


  7. #6
    Member HOROLOGIST007's Avatar
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    Re: seem to get a better wind with bumper movt???

    Quote Originally Posted by Mirius View Post
    Rotor movement isn't the only factor - whether it winds in only one direction or both greatly affects the efficiency. This applies to many early bumpers and rotors. A rotor that 'hangs' frequently can in fact still outperform a uni winding bumper.
    True but the 'Bidynator' Rotor that winds in both directions was not invented till 1942 by Felsa, some 16 yrs after Harwood Bumper and 9 yrs after Rolex Rotor
    NEVER ARGUE WITH AN IDIOT. FIRST THEY WILL DRAG YOU DOWN TO THEIR LEVEL. THEN, THEY WILL BEAT YOU WITH EXPERIENCE.

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  8. #7
    Vint. Forum Co-Moderator Mirius's Avatar
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    Re: seem to get a better wind with bumper movt???

    Indeed but the OP is comparing a modern rotor which surely is bidirectional against a bumper which may or may not be.


  9. #8
    Member lp1974's Avatar
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    Re: seem to get a better wind with bumper movt???

    i thought about the unidirectional issue too..
    i used a jlc powermatic bumper..is it unidirectional ?
    vs a breitling (friend's) which i believe is using ETA

    i could only observe the "hang" moments, and did not measure
    the power reserve as the breitling did not have a power indicator.

    so it is still pretty much gut feel... i noticed that when i wore the bumper,
    i had to wind after 6-7 days. while most of my modern rotor, needed a wind
    every 4-5 days. it may not be accurate, but i tried to be consistent and
    wore same watch at a stretch and my routine is not that different.

    i looked at the design again and i maybe the weight of bumpers being
    mostly around the perimeter, may be a factor.
    JP71624 likes this.

  10. #9
    Member lp1974's Avatar
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    Re: seem to get a better wind with bumper movt???

    Quote Originally Posted by Shum View Post
    Name:  P7113836.jpg
Views: 138
Size:  155.0 KB
    This is a bumper right?

    Don't you need to have that arm really moving to make it work well?
    same for any automatic...movement is important.

  11. #10
    Member AbslomRob's Avatar
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    Re: seem to get a better wind with bumper movt???

    There's a lot of different technologies that impact the integration between the rotor and the winding gears. One of the problems with bi-directional rotors is that you have to have some form of switching mechanism that reverses the direction of how the wheels turned by the rotor intergrate with the winding wheels (which can only turn one way). These designs usually have a "dead" zone, during which the rotation of the rotor doesn't actually turn the winding gear, but instead just moves the switching mechanism. Different designs also have slipping gears and other mechanisms designed to isolate the autowind from manual wind parts. These designs increase the friction in the system and force the rotor to do more work, so the rotor won't necessarily react to small positional changes as much as a less complicated design. Designs like the Seiko's do away with the manual wind for partly this reason.

    In general, however, one would still expect a unidirectional rotor to work better then a bumper, and a bidirectional rotor to wind better then a unidirectional one, all other things being equal. It may come down to how you personally wear your watches and the kinds of hand motions you typically use.
    JP71624 likes this.
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