Set mainspring

[bangster]

I did a search on "Set Mainspring".
Got 3,194 hits.
Rather'n scan all them, I ask once again: What's the criterion for when a mainspring is "set"? Ratio of loose measurement to barrel measurement? As I recall it's something like: "Less than 3 to one, it's set and needs replaced."

Wisdom needed, pliz.

bangster

[Jeff Hamilton]

bangster,

Try doing a search
Content criteria:
Exactly matching: Set mainspring

You will only receive twp pages of results.

Jeff Hamilton

[Jeff C]

Bang,
I consider any spring less then 2 1/2 times to 1 set. I think I also read somewhere here that 5:1 was a guide.

[Mike Phelan]

Any calculation is just an approximation.

I think the criterion is whether it is losing enough power to cause a problem or not.

Most English fusee movements will operate quite well with springs which will only expand to twice the barrel diameter or less. It would be silly to replace it.

Conversely, a 3-train Smiths will fail to chime on the last day or two long before that.

[bangster]

No fusee here. This is from a Mauthe "R-A" wall clock. Time spring is OK. Strike spring uncaged is just slightly over twice the diameter of the barrel. Marginal at best. It wasn't running when it came in, but my guess is that it will run out of strike energy before it runs out of time energy.

bangster

[shutterbug]

If it's disassembled and you are in doubt, a replacement is easier (and cheaper) than a rework later :) You could switch springs, too .... probably. The time side will do better with a weak spring than the strike side.

[bangster]

Oops. Wrong thread.

bangster

[harold bain]

Bang, I don't recall ever seeing a Mauthe serial number bank, such as John Hubby has developed for Beckers. :?|

[Mike Phelan]

The striking train is probably less demanding on spring power on this sort of clock as the hammer and its spring are quite light.

The secret is to know if the spring will last; you can create problems by using an "I'll replace it just in case" approach. :o