Is a non-working mainspring repairable?

debrota

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Jul 2, 2022
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I have a small torsion pendulum clock, with this on the bottom plate:
20220809_084400.jpg

The mainspring seems broken... there is no significant resistance when I try to wind it. Here's a picture of the innards of the clock:

20220809_083619.jpg

Is this likely repairable?
 

Jonas

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Sep 17, 2020
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A mainspring can normally be repaired or replaced fairly easily if someone has the knowledge and the right tools for the job.
As a side note: that’s not a torsion pendulum, it’s a balance wheel, and the spring that you see next to it is called a hairspring.
 
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R. Croswell

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The first thing to do is remove the spring barrel and remove the cover and have a look. The spring may have come unhooked from the winding arbor, or the outer end may have torn out at the hole, or the spring may have broken at almost any place. If the outer end is broken at or very near the end the repair is simple. If the spring is broken any place else, I would replace it. If it is unhooked, check the "hook" on the arbor, the question is why. Quite often when a barreled spring lets go there will be collateral damage to the barrel teeth and possibly a bent 2nd. arbor. Assessing all the damage is the first step.

RC
 

debrota

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Here are some more photos. The "torsion pendulum" is a fake... it's made of light plastic, and is turned by the clockwork. It does not (like a real torsion pendulum) dangle from a piece of spring steel and store and release energy.

20220814_095137.jpg 20220814_095217.jpg 20220814_095323.jpg
 
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Dick Feldman

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Mainsprings, by their nature, pack a lot of energy. It is possible (and likely) that the energy will be released in a very short time, injuring the repairer's hand, face or other body parts. This is true, even if the spring is relaxed in a barrel.
It will be well advised to have someone familiar with mainsprings and having the proper tools to service/replace a main spring.
Stick with something you know.
That is how I feel,
Dick
 

debrota

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I've never opened a mainspring barrel. I'm not sure if its cover comes off easily or has to be pried off. I don't see any screws.
 

Dick Feldman

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All of your comments are danger signs.
No knowledge, no tools, no experience.
High chance of potential injury.
Not worth stitches in one's hand.
Once again,
Stick with something you know.
D
 

R. Croswell

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I've never opened a mainspring barrel. I'm not sure if its cover comes off easily or has to be pried off. I don't see any screws.
Suggest that you do some reading of books on basic clock repair so you will know how to proceed safely. Dealing with springs, you first need to use a letdown tool to totally unwind the spring so there is NO power left. As for removing the barrel cover, do not pry it off. I hold the barrel tight in a gloved hand then sharply whack the arbor (shaft) on the opposite end with a brass or plastic faced hammer and the cover shou pop off. You can also hold the barrel and slam the opposite end of the arbor against a block of hard wood an the cover should pop off.

The danger comes when you try to remove the spring from the barrel. My advice is DO NOT try to remove the spring by hand, and do no attempt to install a new spring by hand - that’s where you get hurt. If you plan to work on other clocks, invest in, or make a decent spring winder, get proper face protection, and learn how to remove the spring properly, or take it to someone who can. If the spring is broken, you won’t be able to extract it with a spring winder and must resort to more dangerous methods like protect everything, yank, and pray. wrapping the work in a heavy towel may help.

you will never learn anything if you never try anything.

RC
 
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shutterbug

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The barrel cap is removed by gripping the barrel in a gloved hand and rapping the winding arbor sharply with a hammer (preferably a fiber one) or slamming the arbor onto a 2x4 or similar. If you rap it hard enough, the cap will pop off so you can see the spring. I agree, it's probably broken, but take a pic for us.
 

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