Pendulum rotates as well as swings. French movement.

dorsetman

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See this French movement just restored. The pendulum twists as well as swings. See attached pics and "hopefully" a video clip. Does not effect the movement but is plainly not right and a bit annoying. The suspension is new but not the same quality as the original broken suspension. The two slivers of spring steel in the suspension are not uniform in size and I am guessing that might be the answer. Can anyone confirm this and/or give any other reason why it all twists?
Also see pic showing the three slots that take the suspension. Why is the middle one at an angle? Whats the point of that?
One more thing. The suspension I suspect was made maybe in India hence poor quality. Where can one get good quality ones preferably in the UK. Thanks for helping. Peter




sus1.jpg sus2.jpg
 

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bruce linde

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the middle slot in the regulating piece in your second photo should be straight up and down and not angled, perpendicular to the bottom of the case.

the brass pieces at the bottom end of the suspension spring could/should be compressed back together.

if the pendulum rod hook fingers are too loose where it hooks onto the bottom of the suspension spring, you can bring them closer together by squeezing or shimming.

you want the suspension spring swinging left and right with as few moving parts as possible.
 
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roughbarked

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Looks to me like the second suspension strip is swinging free of the regulator plates whilst one is held between them. Is the suspension new or a spring found in a box? Does it look as if someone has made repairs to it?
It could simply be that you need a suspension with the two strips closer together? There are a wide range of suspensions available, it could be that you have the wrong spring for the clock.
It also could be that inside the plates on the suspension, that one strip is cracked. Both strips should move in unision. They should also be joined at the hip so to speak. If you pull the suspension plates apart and this is not the case then replace the suspension with one that is.
 
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R. Croswell

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The spring may indeed be defective or incorrect, but it appears that the "chops" in the regulator grip the outer spring strip tighter than the inner spring strip. Or put another way, the spring is too loose in the chops, especially the inner spring strip. Also make sure the slot in the crutch foot is perpendicular to the movement back plate.

RC
 
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Mike Phelan

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Dec 17, 2003
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See this French movement just restored. The pendulum twists as well as swings. See attached pics and "hopefully" a video clip. Does not effect the movement but is plainly not right and a bit annoying. The suspension is new but not the same quality as the original broken suspension. The two slivers of spring steel in the suspension are not uniform in size and I am guessing that might be the answer. Can anyone confirm this and/or give any other reason why it all twists?
That won't make any difference.
Also see pic showing the three slots that take the suspension. Why is the middle one at an angle? Whats the point of that?
None! It shouldn't be and that might be the cause of the twisting.
One more thing. The suspension I suspect was made maybe in India hence poor quality. Where can one get good quality ones preferably in the UK. Thanks for helping. Peter
Apart from secondhand ones, I don't find you'd find any. Might be worth trying Cousins or A G Thomas.
For me, I'd keep the spring if it was still flat and make the block from a bit of brass - drill, tap and slitting saw is all that's needed.
Keep us posted.
 

R. Croswell

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The pendulum should not wobble, and the problem should be fixed. Pendulum wobble usually reduces the swing and is an uncontrolled motion that potentially cause inaccurate or inconsistent timing.

I believe what is going on here is illustrated in this sketch. When the chops of the regulator are too loose to grip the legs of the suspension spring properly, they are often squeezed together. This results in the slot between the chops becoming "V" shaped instead of having parallel sides that are perpendicular to the plate. At the end of the pendulum swing the suspension spring is forced against the chop that is no longer perpendicular to the plate, thus causing the suspension spring to twist and the pendulum to wobble.

The solution depends........ but the slot between the chops must be perpendicular to the plate and have parallel sides. I have found that spreading the chops until they are parallel and inserting a thin shim between the chops and the suspension spring can work.

RC

chops.jpg
 

bruce linde

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sorry... you guys are right, but missing the obvious.... i zoomed in on the video and it sure looks to me like the spring is not even running through the (problematic) angled center slot of the block, but in the groove to the right.

please confirm that both leaves of the suspension spring are in fact running through the (shouldn't be but is) angled center slot and let us know if that makes a difference?
 

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