runaway clock

[estanek70]

I am working on a clock movement with a balance wheel/hair spring escapement. The clock runs but it is very fast, picking up almost ten minutes an hour. I hace tried adjusting the speed control, lengthening the hair spring and loosening the pivot adjustment to no avail. I even replaced the escapement with one from another clock and I get the same result. The clock did not run at all when I got it. I have cleaned and oiled the movement and replaced a set main spring. Does anyone have any ideas on what to do next? Thanks.

[willofiam]

hi estanek70, One quick question that I think has to be asked even though it can sound silly, so please do not take any offense. did you put all the gears in the right place???? 10 minutes per hour is alot. now as I think out loud I am imagining a smaller wheel even by a couple a teeth further down the time train than it should be would speed up a clock, right???? hey, have fun today, William

[Bob Tascione]

Hi Ed and William,
I think your problem could possibly lie with the hairspring. A dirty, corroded or magnetized hairspring can cause what you’ve described. Check to see that no coils are making contact and/or sticking onto one another while the balance is oscillating. Also make sure that the hairspring is horizontal to the plane of the balance wheel and not making contact with the balance arm or bottom of the balance cock during any part of oscillation.
Another thing that can result in a fast rate is a missing balance screw.

Hope this helps Ed,
Good luck and please keep us posted on your progress.
Bob

[estanek70]

I checked the time train and I don’t think any of the wheels are out of place. I also have the movement that I swapped escapements with and I compared the time train with that movement. They look identical. The hair spring on the original escapement has a few coils closer than together one one side verses the other. The hair spring on the second escapement looks perfect. It seems to me that after swapping escapements that the same problem remains the cause of the problem would be elsewhere. However after checking the time train I’m not sure what it could be. Thanks to both for your suggestions.

[Bob Tascione]

Hi Estanek70,
I’m sorry. I should have read your original post better. I didn’t realize you had swapped the platform with one from another clock and received the same results. If that’s the case then is it possible that one or more teeth on the contrate wheel are skipping past the escape wheel pinion? If so this can usually be remedied by moving the platform in towards the contrate for deeper engagement. Another thing you might check for is contrate wheel runout which could allow teeth to clear and slip by the escape wheel pinion leaves during each revolution of the contrate. If all checks out ok then look closely for missing teeth on the contrate or any other wheel. This would produce the condition that William mentioned in his post.
One last thing that you can check for is excessive contrate wheel end shake.

Please let us know what you come up with Ed as knowing the final solution can be make this a very helpful thread for many of us.
Bob

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