Suspension Spring Gone Rogue

Tim M

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Feb 21, 2021
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Can a suspension spring suddenly "go bad" for no apparent reason?

A spring-driven Kienzle wall clock stopped working a few weeks ago. It would run for a few minutes after nudging the pendulum but then slow to a stop. So I disassembled the movement and cleaned it with mineral spirits and a bath in the US, pegged, reassembled, oiled it and put it in beat. It did not appear to need any bushings. No difference. It ran strongly without the pendulum so after eliminating every variable I could, out of desperation I replaced the suspension spring. It's been running like new for a week now. The "new" spring came from the same batch as the old one.

The clock had been on the wall with that spring for 3+ years and hadn't been moved or subjected to shock and never exhibited a hiccup. There's no visible damage, crack, bend, rust or other apparent issues with the replaced spring. As a test I put it back on the clock, making sure it wasn't binding, and the pendulum again slowed to a stop within a few minutes.

I suppose I've answered my own question, but does anyone know the mechanics or metallurgy behind this sudden behavior? It was a very frustrating trouble-shoot since this typically points to a power problem and the spring itself looked fine.

This board is a wealth of information. I've lurked for a long time and found that someone had already asked & answered every question I'd had, till now. Thank you!
 

Willie X

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Feb 9, 2008
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That would be unusual, especially if there were no defects in how the pendulum moved back and forth. Willie X
 

Tim M

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Think I'll just add it to the mental list of things to check before doing a full teardown and move on. Too many other projects on the list.

Thanks Willie!
 

Keith Doster

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Mar 31, 2011
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Can a suspension spring suddenly "go bad" for no apparent reason?

A spring-driven Kienzle wall clock stopped working a few weeks ago. It would run for a few minutes after nudging the pendulum but then slow to a stop. So I disassembled the movement and cleaned it with mineral spirits and a bath in the US, pegged, reassembled, oiled it and put it in beat. It did not appear to need any bushings. No difference. It ran strongly without the pendulum so after eliminating every variable I could, out of desperation I replaced the suspension spring. It's been running like new for a week now. The "new" spring came from the same batch as the old one.

The clock had been on the wall with that spring for 3+ years and hadn't been moved or subjected to shock and never exhibited a hiccup. There's no visible damage, crack, bend, rust or other apparent issues with the replaced spring. As a test I put it back on the clock, making sure it wasn't binding, and the pendulum again slowed to a stop within a few minutes.

I suppose I've answered my own question, but does anyone know the mechanics or metallurgy behind this sudden behavior? It was a very frustrating trouble-shoot since this typically points to a power problem and the spring itself looked fine.

This board is a wealth of information. I've lurked for a long time and found that someone had already asked & answered every question I'd had, till now. Thank you!
I assume there was no difference in the thickness of the two suspension springs you used.
 

shutterbug

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I can't imagine the scenario you describe unless there were a small, perhaps microscopic tear in it somewhere. Maybe it has loosened up in the brass end?
 

Tim M

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Feb 21, 2021
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I ordered a dozen springs a few years ago and these two both came from the same batch. They did come from the auction site so QC is suspect. Lesson learned. Shutterbug, I imagine you're correct but it went into the trash last night and I'm moving on to the next project...a Willmann VR restoration.

Thanks again for your input!
-Tim
 

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