Stopping & reversal of seconds hand in non-hacking movements

Thread: Stopping & reversal of seconds hand in non-hacking movements

Results 1 to 3 of 3
  1. #1
    Member Francois Boucher's Avatar
    Join Date
    Feb 2006
    Location
    Quebec City, QC, Canada
    Posts
    2,118

    Stopping & reversal of seconds hand in non-hacking movements

    I just got my first Speedmaster Pro, a fine timepiece from 1973 or '74. Works like a charm!

    I was very surprised to find out that Cal. 861 does not "hack" (i.e.: the seconds hand does not stop when the crown is pulled).

    Furthermore, just like with Cal. 7s26 in my Seiko diver, it still is possible to stop the seconds hand, or even reverse its course, by turning the pulled crown counterclockwise. That is a way to adjust the watch to the closest second against a standard timekeeper, such as an ntp server, or an atomic clock.

    My questions about this are:

    1. Can anyone explain how this happens in the watch mechanism, or point me to a reference about this?

    2. Can this practice of stopping or reversing the seconds hands damage the movement?

    Thanks for your thoughts.
    Last edited by Francois Boucher; May 7th, 2007 at 17:04.
    François – Quebec City, QC

  2. #2
    Member lysanderxiii's Avatar
    Join Date
    Oct 2006
    Location
    N 32 deg, 47' 27.9168"; W 79 deg, 54' 30.3372"
    Posts
    8,842

    Re: Stopping & reversal of seconds hand in non-hacking movements

    1) When you set a watch (hacking or not) the stem, through some gear wheels, is put in direct contact with the cannon pinion , which is nothing nmore than a friction clutch. Moving the crown slides one part of the pinion or another part to change their relative position. If the friction on the pinion is greater that the force applied by the spring (geared down by the 4 main wheels) the movement will stop or even reverse. If the friction is not greater than the spring force it will not stop. Ideally, the cannon pinion should be tight enough to reliably move the hands but light enough not to stall the movement when setting, but it's better to set it on the tight side, because over time it will wear and get looser.

    2) No, it shouldn't, but other may have differing opinions.

  3. #3
    Member Francois Boucher's Avatar
    Join Date
    Feb 2006
    Location
    Quebec City, QC, Canada
    Posts
    2,118

    Re: Stopping & reversal of seconds hand in non-hacking movements

    Thanks for your answer!

    I also read again Walt Odets' article on The Motion Works on the other forum, and together with the details you provided, I now understand much better what I could not figure out after my first reading of Odet's excellent discussion.

    :thanks
    François – Quebec City, QC

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

    Similar Threads

    1. Thermocompensation: Methods and Movements
      By hedrick in forum High Accuracy Quartz watches
      Replies: 44
      Last Post: 3 Hours Ago, 20:43
    2. A question about Wave Ceptor frequency reception
      By Matty in forum Casio G-Shock
      Replies: 9
      Last Post: January 30th, 2007, 12:25
    3. Thermocompensation: Methods and Movements
      By hedrick in forum Links & Articles
      Replies: 14
      Last Post: October 29th, 2006, 16:31
    4. Please explain ETA movements
      By gregfsu in forum DOXA Owners Club
      Replies: 10
      Last Post: October 25th, 2006, 06:45
    5. hacking seconds ?
      By MarcoParis in forum DOXA Owners Club
      Replies: 3
      Last Post: April 14th, 2006, 23:11

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •