Fusee Clock Mainspring Adjustment Query

Gr8ham

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Dec 13, 2010
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Toronto, ON, Canada
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Evening folks,

I’ve been working on an English two fusee clock movement off and on for some months. I’ve got it reassembled and it runs nicely. I’m curious about the fine tuning of the time side mainspring. Currently the pre-load/set-up is one full turn of the mainspring arbor. The clock slowly gains 5-10 seconds/day in the first few days of running then starts to increase the gain until by day 7 it has gained 90 seconds.

Would the solution be more or less tension on the mainspring?

Thanks!
 

wow

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Jun 24, 2008
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I don’t know what most people do but I have three and I only set the spring at 1/4 turn. I think it gives them more even power throughout the week.
 

Willie X

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Feb 9, 2008
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First, I would slow it down a bit. If those early gains are reversed to losses you will be in good shape.

A fusee helps flatten a springs torque curve but it's not a perfect solution and all bets are off when the spring is changed.

Willie X
 

Gr8ham

Registered User
Dec 13, 2010
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Toronto, ON, Canada
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First, I would slow it down a bit. If those early gains are reversed to losses you will be in good shape.

A fusee helps flatten a springs torque curve but it's not a perfect solution and all bets are off when the spring is changed.

Willie X
By slow it down you mean lower the pendulum bob rather than adjusting the pre-tension, right?
 

klokwiz

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Feb 4, 2009
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Like Will said 1/4 turn is enough but don't think 1 turn is too much. Agree with Willie that you should regulate the clock with pendulum. Frankly your 90 seconds is damn good for starters, if that is total gained in week. Maybe you should compromise, back off the pre set to 1/2 turn and if you really want to experiment see if that has any effect on the regulation before adjusting the pendulum. Joe .
 
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