Newbie Question about long drop vs short drop

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  • #48139
    john
    Participant
    • Topics Started: 7
    • Total Posts: 13

    One more of my famous newbie questions. I have a sessions short drop school house clock I am trying to restore. I picked up some used movements , cleaned and installed one. I can not slow down the speeding time. The bob is all the way at the bottom and it still is running fast. Could there be a difference in short drop and long drop pendulums ? I assume there is, so how can I tell the difference when viewing the movement. This is a time only sessions movement. Thanks in advance .

    #50898
    Bob Tascione
    Moderator
    • Topics Started: 38
    • Total Posts: 1559

    Hi John,
    I’ve held off answering your post in hopes that someone up here knew of a quick way to determine pendulum length for Sessions. Short of calculating the train I can’t think of any way other than the lazy way I do it. When in doubt I usually just hang different length pendulums and check the timer until I get close. There may be a quicker way like different escape wheel teeth count. Maybe someone here has the answer or has a few Sessions movements laying around they can check.
    Sorry I couldn’t offer more help John.

    Bob

    #50899
    john
    Participant
    • Topics Started: 7
    • Total Posts: 13

    Bob, thanks for the reply. I guess a timer will be one of the items for my wish list. I have tried counting the drive train teeth, and then trying to apply the formula for each gear…. I think the timer will be the best way to go. thanks…

    #50900
    Bob Tascione
    Moderator
    • Topics Started: 38
    • Total Posts: 1559

    Hey sorry John…that’s a typo on my part. Didn’t mean “timer” but rather “time”. I just let it run for a while and check to see if it’s keeping time. If it’s real slow or fast over a period of time I then make an extreme adjustment and keep track of the change. Then make one or two more adjustments and can usually get close fairly fast. Again…I’m pretty lazy. The best way is just to do a train count but then I have to think!
    Bob

    #50901
    john
    Participant
    • Topics Started: 7
    • Total Posts: 13

    Bob, thank you . You answered my question and now with the clarification of timer and time, you just saved me a few hundred dollars ha ha. I like this solution the best as far as just track if its running fast or slow. Thank you.

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johnNewbie Question about long drop vs short drop