Forestville 400 day part

Discussion in '400-Day & Atmos' started by Kenney, Mar 25, 2019.

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  1. Kenney

    Kenney Registered User

    Mar 21, 2019
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    I was given a Forestville 400 day clock with a broken suspension spring. I an find little to no help on the internet for this clock. Any idea on the size spring I need to replace it. I put a .0020 on just to see if the clock functioned, but it just chatters badly. IMG_0269.JPG IMG_0270.JPG IMG_0271.JPG

    IMG_0269.JPG IMG_0270.JPG
     
  2. sjaffe

    sjaffe Registered User

    Dec 25, 2012
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    Santa Rosa,CA
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    Hi Kenney,

    I believe this clock is very similar to a Kundo Standard which uses a 0.0032" suspension spring. The thickness of the spring determines how fast or slow the clock runs. 0.002" is too thin and the clock will probably run too slow. You can stop the "chatter" by altering the fork position.

    Stan
     
  3. Kenney

    Kenney Registered User

    Mar 21, 2019
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    Thank you. The .002 was a guess on my part and it was handy. I'll try the .0032. I can never remember which way to move the fork up or down.
     
  4. KurtinSA

    KurtinSA Registered User
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    Nov 24, 2014
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    Welcome to the message board! If the fork is too low, it can flutter. The idea is to lower the fork until you hear the flutter then raise it a millimeter or so. If it's fluttering now, then seems you should start to raise it in steps until it stops.

    From the picture, it appears to be plate 1119 made by J. Link & Co. Guide says it takes a 0.0037" suspension spring.

    Kurt
     
  5. Kenney

    Kenney Registered User

    Mar 21, 2019
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    So I tried the .0032 spring first since I had one. The pendulum got sped up to max and the clock was too slow and lost 15 min/dy. The pendulum travel was about 360 deg. I tried the .0037 spring and slowed down the pendulum to max and it still gains about 5 min/dy with travel at about 180 degrees. So my logic tells me to try a .0035 spring. Any thoughts or tricks to try before I order the new springs? Thanks for your help.
     
  6. KurtinSA

    KurtinSA Registered User
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    Nov 24, 2014
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    It's important to be a bit more specific on gain/loss times..."about" can be misleading. It would be best to know how much the clock is off with the pendulum adjustment in the middle of the range. Knowing precisely how much it gains/loses in that situation allows for a calculation for another spring size. Then if the chosen spring size is slightly off, you still have adjustment in the pendulum to get back to regulation. Typically, a change of thickness of 0.0001" equates to 4 seconds per minute change in time.

    Kurt
     
  7. Kenney

    Kenney Registered User

    Mar 21, 2019
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    Thanks Kurt. I'll move the pendulum to the middle and try to get a better gain/loss. Any preferred length of time y'all use for this?
     
  8. KurtinSA

    KurtinSA Registered User
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    Nov 24, 2014
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    How about 60 seconds! :clap: Start the pendulum by rotating it one way about 180 degrees. Let it go and wait maybe 2-3 minutes to let it stabilize. Then with a stopwatch, measure the time for 8 beats, then do the math. If you're roughly 4 seconds off at that point, you can go one size up or down. If you're 2 seconds off, then it's tougher. If it's fast, as in it takes 58 seconds for 8 beats, then you might be able to turn the adjust all the way to one side and see if you're back to 60 seconds. But doing that doesn't give you any future adjustment. Best to find a spring where you're off something like 59.2 or 60.3 seconds...well within adjustment range.

    A thicker spring is going to be faster, but a process of thinning the spring can reduce the thickness to bring the time down. Thinning has been discussed before...it involves dragging the spring between sandpaper which squeezing with your fingers.

    Kurt
     
    Kenney likes this.
  9. Kenney

    Kenney Registered User

    Mar 21, 2019
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    Thank you Sir for this great information. It is very much appreciated and should make the decision accurate, instead of me just guessing. Thanks again.
     

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