Fusee power

Discussion in 'Clock Repair' started by Ron751, Jul 10, 2019.

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  1. Ron751

    Ron751 Registered User
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    Sep 2, 2011
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    The brass cable in my fusee movement recently broke while winding - there was no damage.
    I replaced it with the same length of gut & used a prescribed method to set the preload.
    The clock had previously run about 6.5 days.
    Now it runs about 4 days w/half of the fusee cone still wrapped.

    The preload procedure is one recommend by a member & has worked fine in all my movments.
    The spring is wound VERY tight now & I would not want to push it any further.
     
  2. novicetimekeeper

    novicetimekeeper Registered User

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    I would expect it to run 8 days, so that it can be wound once a week
     
  3. Uhralt

    Uhralt Registered User
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    That sounds odd. When the clock stops, is there still tension on the spring? Can you describe your method of setting the pre-tension?

    Uhralt
     
  4. Ron751

    Ron751 Registered User
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    They usually run at least 8 days on a full wind - the barrel spring has to preloaded to make it go the full perod - 8 days or more
     
    Altashot likes this.
  5. Ron751

    Ron751 Registered User
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    There is still some tension on the spring - but it doesn't appear to be enough....

    "I start with the fusee chain wound entirely around the fusee, except for a portion sufficient to reach the barrel. At this point, the spring is unwound. Then I give the mainspring barrel winding arbor a couple turns, and let the clock run until it stops, run down. Then give the winding arbor another turn, and set the clock running again. I do this until it runs 8 or 9 days. THEN I wind it fully at the fusee, and check the stop works when it is wound."
    This has worked on all my movements
     
  6. Uhralt

    Uhralt Registered User
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    Your method is fine in principle. However, before you set the pre-tension you should let the clock run down until the chain (or gut) is almost fully on the barrel and very little left on the fusee. Than put the anchor back on and put 1 to 1 1/2 turns of pre-tension on the spring. Then fully wind the clock. Now it should run for the full 8 days.

    Uhralt
     
  7. Ron751

    Ron751 Registered User
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    I'll try it but I am pessimistic about it.....
     
  8. Uhralt

    Uhralt Registered User
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    Let us know what you find.

    Uhralt
     
  9. Ron751

    Ron751 Registered User
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    I will !
     
  10. MartinM

    MartinM Registered User

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    When it stops at 4 days, how many turns does it take to let it down, fully?
     
  11. Ron751

    Ron751 Registered User
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    After ~ 4 1/2 - 5 days . - it took 1.5 turns to let it down fully.
     
  12. Ron751

    Ron751 Registered User
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    I followed Uhralt's directions- only I made 2 turns on the barrel instead of 1.5.
    It was crazy tight winding it after. I stopped before finishing - the last 2 grooves were "empty"

    I don't know if the additional turn on the barrel could have caused this ??

    Having to wind it that tight every 7 days seems a bit bizarre. My other fusees wind easily right to the end.

    We will seeo_O
     
  13. Willie X

    Willie X Registered User

    Feb 9, 2008
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    Sounds like your spring is too short.
    WIllie X
     
  14. Ron751

    Ron751 Registered User
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    I wonder about that......o_O
     
  15. Uhralt

    Uhralt Registered User
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    The clock didn't run for a full week before the cable broke, so that's clearly a possibility. On the other hand, when you reduce the pretension for a half turn you should be able to fill the last two turns of the fusee because the diameter is small. The clock should then also be a bit easier to wind. You might even try a pre-tension of only one turn.

    Uhralt
     
  16. novicetimekeeper

    novicetimekeeper Registered User

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    should the clock not be the same to wind throughout the whole spring? That's what the fusee is for in reverse.
     
  17. Ron751

    Ron751 Registered User
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    Uhralt, That's what I'm going to do - one turn next cycle.

    Novice - you are right this is all so strange. With my old cable it wound smoothly til the end. I think this is a preeload issue...
    unfortnately, we have to wait a week for adjustments.
     
  18. Ron751

    Ron751 Registered User
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    *OK - it ran for 8 days. I am going to give it one turn, as suggested. I think that will give the proper duration & solve the tight winding situation .
     
  19. kinsler33

    kinsler33 Registered User

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    There's no way to get things upside-down in a fusee movement, is there? The winding torque should have been perfectly consistent throughout the wind
     
  20. Ron751

    Ron751 Registered User
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    Yes, you are correct. I used too many turns of preload, which resulted in the over-tight winding.
     
  21. Uhralt

    Uhralt Registered User
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    Glad you got it solved.

    Uhralt
     
  22. Probox

    Probox Registered User
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    I enjoy working on fusee's and I totally agree with and use Uhralt's method. It''s easy and works. Some mainsprings need 1.5 winds, some need 2.0 full winds of pre-tension.
     

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