Author Topic: Strengthening a Main Spring?  (Read 657 times)

Offline Bob Gerard

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Strengthening a Main Spring?
« on: February 05, 2025, 05:21:41 AM »
Can an existing Main Spring be strengthened (and the Feather Spring as well)?
I have a new-to-me flintlock pistol with a rather crude lock. It sparks and shoots OK, but certainly not great. The springs are very light- too light I think, to produce a good spark. I've had it for two days and feel unsatisfied with the lock's reliability. It is a recreation of a 1690 French Dragoon pistol from The Rifle Shop.
Can these existing springs be re-tempered or what ever a good gunsmith does to make springs? I guess a new main spring could be forged but not sure about the Feather Spring because of its unique design.

Thanks very much for any ideas and suggestions,
Bob




Offline rich pierce

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Re: Strengthening a Main Spring?
« Reply #1 on: February 05, 2025, 05:46:17 AM »
Preload can be increased on a frizzen spring. There’s little actual compression. To do that it’s heated bright red, spread by maybe 1/8” more, hardened and tempered.

How low below the lock plate would the mainspring hook be if free of the tumbler and completely relaxed? In my limited experience a new, thicker spring is a better solution than increasing preload.  Cabin Creek is the go-to shop.
Andover, Vermont

Offline Bob Gerard

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Re: Strengthening a Main Spring?
« Reply #2 on: February 05, 2025, 06:10:59 AM »
Hi Rich,
I have not disassembled the lock yet to see how much the Mainspring opens. I did take your advise and emailed Cabin Creek Muzzleloading to see if it is something they would work on.
Thanks very much for your advise!

Offline smart dog

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Re: Strengthening a Main Spring?
« Reply #3 on: February 05, 2025, 03:50:49 PM »
Hi Bob,
You may be able to heat it red hot, open the main bend a little and give more arc to the lower leaf.  However, if you alter the spring make sure the lower leaf is straight when the lock is at full cock.  A very slight upward bend is OK but straight is better.  Don't be afraid to alter the spring, harden and temper it and then test it.  If it still isn't right reshape and heat again as many times as you need.  Contrary to what some would have you believe, springs can be hardened and tempered many times without damage if you do it right.  For TRS springs do not quench in oil.  Quench them in brine, which cools them much faster without risk of cracking. They are not very high carbon steel and oil quenching tends to create mushy TRS springs. Temper at 750 degrees for at least 30 minutes, an hour is better.

dave
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Offline Bill in Md

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Re: Strengthening a Main Spring?
« Reply #4 on: February 05, 2025, 04:02:15 PM »
interesting thread
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Offline Bob Gerard

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Re: Strengthening a Main Spring?
« Reply #5 on: February 05, 2025, 07:10:01 PM »
Hi Bob,
You may be able to heat it red hot, open the main bend a little and give more arc to the lower leaf.  However, if you alter the spring make sure the lower leaf is straight when the lock is at full cock.  A very slight upward bend is OK but straight is better.  Don't be afraid to alter the spring, harden and temper it and then test it.  If it still isn't right reshape and heat again as many times as you need.  Contrary to what some would have you believe, springs can be hardened and tempered many times without damage if you do it right.  For TRS springs do not quench in oil.  Quench them in brine, which cools them much faster without risk of cracking. They are not very high carbon steel and oil quenching tends to create mushy TRS springs. Temper at 750 degrees for at least 30 minutes, an hour is better.

dave

Thanks Dave- I wish I felt competent to do that work, but in all honesty I don’t. I shipped it out today to Brad Emig after talking with him about it. It’s such a cool gun I would hate to make things worse by experimenting on it.

Offline Bob Roller

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Re: Strengthening a Main Spring?
« Reply #6 on: February 05, 2025, 10:23:07 PM »
When OLD springs are involved they are frequently made from "Mystyrium"and it's a roll of the dice when you anneal it,change the pre load and the reheat,quench and temper.Good luck.
Bob Roller
« Last Edit: February 06, 2025, 07:54:29 PM by Bob Roller »

Offline rmnc3r

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Re: Strengthening a Main Spring?
« Reply #7 on: February 06, 2025, 10:19:24 PM »
I don't recall the source, but I recall seeing photo of a lock with a wedge of wood or brass inserted at the bend, between the mainsping legs to spread 'em a bit - likely an expedient repair while out in the field...?

Offline JTR

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Re: Strengthening a Main Spring?
« Reply #8 on: February 06, 2025, 10:36:56 PM »
I've seen several old locks with a wedge of iron or some metal wedged in to strengthen the spring, as rmnc3r pointed out. But usually on lower end guns.
John
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Offline t.caster

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Re: Strengthening a Main Spring?
« Reply #9 on: February 07, 2025, 02:05:29 AM »
Bob, I hope you shipped them the entire lock, not just the springs.
Tom C.

Offline Bob Gerard

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Re: Strengthening a Main Spring?
« Reply #10 on: February 07, 2025, 05:38:55 AM »
Bob, I hope you shipped them the entire lock, not just the springs.

Hi Tom- yes I shipped the whole lock, with the flint in as well. I’m looking forward to having a fine sparking lock soon.

Offline Bob Roller

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Re: Strengthening a Main Spring?
« Reply #11 on: February 07, 2025, 06:43:53 PM »
I don't recall the source, but I recall seeing photo of a lock with a wedge of wood or brass inserted at the bend, between the mainsping legs to spread 'em a bit - likely an expedient repair while out in the field...?

This type of "repair" was an expedient and I have also seen them.The old saying that "poor people have poor ways"applies here and I well remember the "Bad old days" when anything made for a muzzle loader HAD to be CHEEEEP! I thought about making some cross bolts to  hold the lock on a muzzle loader but $4 was TOO much so I forgot about it.The cost of quality material,the electric bill,the skill of the machinist and being willing to make one or two meant nothing.I remember some of the local shooters that would start by saying *When I was a boy" and I still tell them to "put a cob in it,that was back when a dollar had value".My hourly charge was $25 an hour for odd jobs and car hobbyists thought it was cheap.I was making "on request" bronze bearings for whatever needed them and would make only one if that was what was needed.I told more than one caller that I can't make less than one.IF I was able to stand for a long time I'd restart the bearings again but not now.(or later) ;D.
Bob Roller

Offline rich pierce

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Re: Strengthening a Main Spring?
« Reply #12 on: February 07, 2025, 07:40:03 PM »
We’d call inserting a wedge or old sear spring into the bend of a mainspring  a “cob job” when I was growing up, but as Bob Roller said, poor people make do. Many archaeological digs around forts and native settlements show all sorts of ingenious or expedient or poor repairs. As my Dad used to say, “a poor excuse is better than none!”
Andover, Vermont

Offline Top Jaw

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Re: Strengthening a Main Spring?
« Reply #13 on: February 07, 2025, 09:52:56 PM »
We’d call inserting a wedge or old sear spring into the bend of a mainspring  a “cob job” when I was growing up, but as Bob Roller said, poor people make do. Many archaeological digs around forts and native settlements show all sorts of ingenious or expedient or poor repairs. As my Dad used to say, “a poor excuse is better than none!”


I’m gonna add your Dad’s quote to my list of wise sayings Rich!  😆