Gravolas keeps stopping

Discussion in '400-Day & Atmos' started by Dells, Mar 15, 2020.

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  1. Dells

    Dells Registered User
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    Oct 18, 2019
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    Hi all
    I am hoping someone can give me some suggestions as to why my Grivolas torsion clock keeps stopping?
    The movement is the Gravolas own and there seems to be no common hand position or length of time, sometimes it will run for a couple of days or a couple of weeks, all I have to do to set it going again is Re set the time and start the disc pendulum again then it will work fine again and it keeps good time.
    When I purchased it I could not find the correct torsion spring so it has a thinned down 0.045 but after setting the beat and a few times fine tuning it runs fine until it will stop all of a sudden and I can’t find any reason for it.
    If anyone has any suggestions it would be mush appreciated.
    Thanks in advance Dell
     
  2. KurtinSA

    KurtinSA Registered User
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    Nov 24, 2014
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    I don't have specific experience with the Grivolas to know if there a special aspect of the movement that needs attention. I have run across several clocks that work as you suggest...runs for a while, sometimes short durations, sometimes longer. I have begun to notice that some of these clocks - older clocks, clocks with thin plates - probably could stand to have a few bushings replaced. If the pivot holes wear enough, it will change the depthing that the wheels and pinions have.

    Kurt
     
  3. Dells

    Dells Registered User
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    Oct 18, 2019
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    Thanks Kurt
    I hadn’t thought of that because wear is minimal on torsion clocks but it’s worth a look, I was thinking of striping and cleaning the movement anyway as I haven’t done it yet, just replaced the torsion spring.
    Dell
     
  4. John Hubby

    John Hubby Principal Administrator
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    Sep 7, 2000
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    Dell, how did you thin the suspension spring?? If you thinned only between the fork and bottom block that is likely your problem, because the section between the fork and bottom block is now too thin and the section between the fork and upper block much too thick. That small section between the fork and upper block actually is much more important than the long lower section, especially when you are having to remove about 0.0004 inches to get the equivalent performance of the correct spring (0.0040 in.). No question you will get erratic performance with the spring so much out of balance.

    The best thinning procedure is to remove both the fork and upper block, hold the bottom block and stroke the entire length of the spring from bottom to top. You can test by just installing the top block, hanging from a stand or the upper suspension bracket of the clock, hang the pendulum and give it about a 3/4 turn and let go. It will rotate plenty long to measure the rate; you want to have it just a bit fast, e.g. 59 to 59.5 seconds to make 8 beats.
     
  5. Dells

    Dells Registered User
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    Oct 18, 2019
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    Hi John
    That is exactly how I thinned it holding bottom block, it keeps good time when it is running and it will run for days or weeks and when it stops it’s not at a certain time, all I do is set time again and start the pendulum and it runs again for days or a few weeks.
    Very frustrating Dell
     

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