Too fast or too slow

Discussion in '400-Day & Atmos' started by Dells, Nov 27, 2019.

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  1. Dells

    Dells Registered User

    Oct 18, 2019
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    Hi all
    I have a Gravolas and a Gustav Becker and both of them to slow with 0040 and pendulum wound all the way in and with 0045 to fast with pendulum wound all the way out, has anyone got any suggestions.
    Many thanks in advance Dell
     
  2. whatgoesaround

    whatgoesaround Registered User

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    Probably the best bet would be to thin the larger spring in small increments.
     
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  3. Wayne A

    Wayne A Registered User

    Sep 24, 2019
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    Sounds like you need a suspension spring size that falls somewhere between those two. One option is to put in the .0045 and thin/test the spring until you get the pendulum into range. You can make a little sandpaper tool out of wood like popsicle sticks so you can sand both sides of the spring at the same time. Make a few passes with 600-800 grit and test.
     
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  4. Dells

    Dells Registered User

    Oct 18, 2019
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    Thanks for reply’s
    Do I sand the edges or the flat ?
     
  5. Kevin W.

    Kevin W. Registered User
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    You are sanding the flat of it. Check often as mentioned, it goes quicker than you think.
     
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  6. KurtinSA

    KurtinSA Registered User
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    Nov 24, 2014
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    Also, the portion of the spring between the fork and top block is the most important. I usually leave the bottom block on and sand the spring from there to the top and off the end.

    I thought we had an interesting discussion in this thread about finding the right spring. I don't think I can measure the thickness accurately as it changes, so the idea of using a "spin test" as you thin the spring to size. First try a spin to see what the timing is then rehang the pendulum and spring to see how the timing changes as it thins. There is an issue with spring length which is what I was sort of discussing in the thread, but Eric had a good suggestion about putting the top block in place at the proper length and see what the timing is.

    Choosing the right suspension spring

    Kurt
     
  7. etmb61

    etmb61 Registered User
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    Oct 25, 2010
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    Most of the old disc pendulums (if not all) require a non-standard spring size. People have done some really strange (and scary) things to them over the years trying get them to keep time with the springs they had available. Thinning a modern spring is not that difficult or critical, though some of the instructions I've seen try to make it seem like it is.

    Eric
     
  8. Dells

    Dells Registered User

    Oct 18, 2019
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    Thanks Kurt & Eric
    I did read the post you linked to I also understand that making the spring longer or shorter changes things but I think I will stick with thinning and see what I can do, I tried changing length and it looks all wrong with the pendulum to high ( I used an old spring to save wasting a new one.
    Dell
     
  9. KurtinSA

    KurtinSA Registered User
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    Nov 24, 2014
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    My point was that I have an aversion to cutting a spring before I've determine that it is going to work. Even though the guide might suggest a spring size, sometimes due to differences in the pendulum, the time can't be regulated. So there are ways to test the spring with the pendulum to confirm it is correct. Then you can cut with confidence.

    Kurt
     
  10. Dells

    Dells Registered User

    Oct 18, 2019
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    Well have sanded 0045 down 10 strokes with 400 & 10 strokes with 1200 set pendulum adjuster to approximately the middle and now Gravolas is running about 20 seconds slow per hour so that should be easy to alter on pendulum adjuster.
    Now to do Gustav Becker.
    Thanks everyone
    Dell
     
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