Backup replacement mainspring

[P.W.Berkuta]

I purchased a backup replacement mainspring for one of my civil war rifled muskets the other day. The short leg & bend area was nicely polished but the long leg that attaches to the stirrup link of the tumbler has a lot of cross grain grinding marks. These marks are easily seen & can be felt with the fingernail. I will be sanding & polishing them out before I use the spring. I have no doubt that the spring will do it's job but for how long is the question.



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[Standing Bear]

All bearing/wear surfaces should be polished. I see no reason to dress up lock internals that are not bearing on another.  $0.02.

[Bob Roller]

All bearing/wear surfaces should be polished. I see no reason to dress up lock internals that are not bearing on another.  $0.02.

One of those crossways scratches will be deeper than the others and that is a built in
fracture point.As a lock maker I disagree with the idea of not "dressing up"all parts of
a lock. I can look at a lock and tell you first of all what does he think of himself and most important
what he thinks of the customer that buys it.

Bob Roller

[Smoketown]

Yep,

+2 on what Bob said.

Stress risers ...   

"All grinding and polishing should be in the longitudinal direction to prevent transverse cracking".

I jus had to use somadem dolla woids!   

Cheers,
Smoketown

[P.W.Berkuta]

Just for "giggles" I removed the lock on this rifled musket and looked at it's original mainspring and although the replacement backup mainspring was not made by the same manufacture (? replacement backup spring purchased from competitor rifle manufacturer parts list) both springs had cross grain grinding marks. I purchased this rifled musket in 1999 and the replacement mainspring was purchased a week ago both springs are identical and swap out with no issues except fot the tab that hooks under the bolster - too thick needs a bit of thinning. Never took notice of it before I guess I will be polishing out grinding marks on both mainsprings in the near future.
 

[D. Taylor Sapergia]

I would polish them out for sure, but I have mainsprings from some decent antiques that show much deeper file marks than those, and they are still good today.  Sloppy work then and now, is sloppy work.

[rich pierce]

Just don't make it weak!  As a bowyer I know it doesn't take much thinning to lose power.

[P.W.Berkuta]

I hear ya -- I thought the same thing. I'll do one and see how it performs.

[Longknife]

I have a circa 1820 flint fowler and upon disassembling the lock I discovered the same thing. The main spring has numerous grind/file marks across the surface. The spring is very stout and the lock throws an EXCELLENT shower of sparks. Although it is advised that a main spring should NOT have any grind marks in it I decided that "if it ain't broke......"...IMHO,,,Ed

[g2608671@verizon.net]

Just don't make it weak!  As a bowyer I know it doesn't take much thinning to lose power.

To "tiller" or not to "tiller" - that is the question.  Take a few scrapes here and a few there and then again and again and before you know it a tooth pick has been made of a perfectly good piece of Osage orange. 

[Bob Roller]

I would polish them out for sure, but I have mainsprings from some decent antiques that show much deeper file marks than those, and they are still good today.  Sloppy work then and now, is sloppy work.

I don't recall ever seeing a top of the line lock spring with such lines across it.
Maybe draw filing will work instead of trying to polish it.

Bob Roller