Too strong a spring - how do you fix this

[Sudsy]

I like to avoid grinding through the turn back which puts grind marks across the edge grain in the turn.

Does that matter much if you polish to a mirror finish ?

 

[M. De Land]

Does that matter much if you polish to a mirror finish ?

Polishing is good if it reaches to the crack or file cut bottoms but does not prevent failure if it doesn't. Maintaining the full width in the turn back with dressed edge corners (assuming proper heat treat) is the best prevention I'm aware off because it reduces movement (flex) in the most vulnerable part of the spring.

 

[Sudsy]

It looks like virtually all of the flex is in this area

 

[LRB]

It occurs to me reading @Rock Home Isle ‘s post that some folks may not realize that grinding/sanding things with gloves on is dangerous, as the belt or wheel can grab onto a glove and pull your hand into the workings. I personally have grown partial to having working hands over the years. Be safe.

40 years of grinding knives with gloves on tells me that is not true for all grinding functions. I would add to the having max integrity of a spring, never make a bend in your spring that is not red hot.

 

[M. De Land]

It looks like virtually all of the flex is in this area

View attachment 155967

True, the majority is.

 

[The Appalachian]

@M. De Land

The turn back provides almost nothing to the overall function of the spring, other than connecting the two legs. Thinking any different is overthinking something that's not understood.

You lost me when you said you grind both sides. There's an alignment pin in the way on the inside, on most quality locks, and not easy to clean up around. Not to mention the little "hook" that locks in under the bolster.

As long as the inside rides uniformly against the plate that's all that's necessary. The lock maker takes care of that and for a builder like me it's just more sensible to grind the other side and not create more unnecessary work for myself.

Making these springs correctly is difficult, which is why I don't make them, until someday I'm forced to. If you're having failures in yours then I suggest figuring out how to make better springs.

 

[M. De Land]

@M. De Land

The turn back provides almost nothing to the overall function of the spring, other than connecting the two legs. Thinking any different is overthinking something that's not understood.

You lost me when you said you grind both sides. There's an alignment pin in the way on the inside, on most quality locks, and not easy to clean up around. Not to mention the little "hook" that locks in under the bolster.

As long as the inside rides uniformly against the plate that's all that's necessary. The lock maker takes care of that and for a builder like me it's just more sensible to grind the other side and not create more unnecessary work for myself.

Making these springs correctly is difficult, which is why I don't make them, until someday I'm forced to. If you're having failures in yours then I suggest figuring out how to make better springs.

The pin is usually closer to the turn back if not on it, in the top leg, back side and usually is left as formed but ( top leg) could easily be profiled as described if needed. If one can get both legs bending and working together it will be better balanced and last longer.
Most broken lock springs I've replaced are cast and original to the lock. I don't remember ever having to replace a spring I've made from spring stock ,flat ,coil or torsion. Also, quite often the lower leg of a turn back spring will already have a taper from both sides. I don't usually like to mess with the thickness taper when possible as the width is easier to adjust/ regulate but I have on occasion when needed.
The turn back does indeed flex and is the point of maximum stress in this style of spring. It is also because of this the most likely place for a crack to originate and propagate. The better it is dressed out to remove cracks or file cuts and the thicker and wider it can be left to make it stiffer and flex less, the longer the spring will last.
One mans opinion based on a fair amount of spring making over a 40+ year gun work span.

 

[The Appalachian]

Opinions, everyone has one. You're also trying to introduce an element here that isn't within the context of the OP's question, he's not making springs from scratch, he's fixing one.

I'm not here to convince you of anything, but I have my own experience as well.

Most times I'm looking to keep the spring from intruding into the ramrod channel, and most times a lock can benefit from reducing the main spring anyway. So, narrowing the turn back portion isn't something I'm scared of and I'll just leave it at that.

 

[M. De Land]

Opinions, everyone has one. You're also trying to introduce an element here that isn't within the context of the OP's question, he's not making springs from scratch, he's fixing one.

I'm not here to convince you of anything, but I have my own experience as well.

Most times I'm looking to keep the spring from intruding into the ramrod channel, and most times a lock can benefit from reducing the main spring anyway. So, narrowing the turn back portion isn't something I'm scared of and I'll just leave it at that.

When one learns how to make, heat treat and balance reliable springs from spring stock, tuning existing equipment is not a mystery.

 

[The Appalachian]

Pat yourself on the back and keep on keepin' on....I'll do the same.

 

[M. De Land]

Pat yourself on the back and keep on keepin' on....I'll do the same.

The point is to give the original poster a workable solution to his question that can both improve the original spring function and make it last longer. The defense of why it works and how it came to be was in response to your dismissal of the advised solution.

 

[The Appalachian]

Um, no sir.

YOU quoted me first starting an argument with what I posted.

The point is exactly to address the OP's question and concern, and I'll repeat, he wasn't asking about making a spring.

Lots of good advice here from several posters and MY point here was to reinforce what they posted and add a clarification where and what to grind, and MAINLY WHY due to the physical properties of a leaf spring.

You chose to add a different element and to take it down another rabbit hole to support your apparent umbrage with my post. Have a great life, you're future content is now on ignore.

I do love that function on this site.......

 

[M. De Land]

Um, no sir.

YOU quoted me first starting an argument with what I posted.

The point is exactly to address the OP's question and concern, and I'll repeat, he wasn't asking about making a spring.

Lots of good advice here from several posters and MY point here was to reinforce what they posted and add a clarification where and what to grind, and MAINLY WHY due to the physical properties of a leaf spring.

You chose to add a different element and to take it down another rabbit hole to support your apparent umbrage with my post. Have a great life, you're future content is now on ignore.

I do love that function on this site.......

Now they're s an open mind !

 

[GREENSWLDE]

Now they're s an open mind !

Here Here. to you & Appalation Learning to make your own Better Bits is part of the fun and then you can help others with their poorly made factory repro bits. Some one meantioned a "Bolster".. Did they mean Brible ,the curly bit that supports the tumbler on the inside of the lock ?? Only been a spring maker for 70 anno's. If you're going to start, No better steel than EN 42 or 45 / CS 70 or 75 . Strip usually found at Model engineering shops.. OLD DOG..

 

[Mr. Flintlock]

I recently picked up an Intercontinental .36 Kentuckian Jaeger flintlock. Was a wall hanger, never shot. Have about 50 shots through it.
Not a bad little gun but the mainspring is far too strong, actually hard to **** and eats flints, had to replace the first one after 30 shots.

How to you go about lightening the tension ?

View attachment 155700

If you lighten the mainspring, you may have issues with the **** falling into the halfcock notch. There is no fly in that lock.

 

[Sudsy]

If you lighten the mainspring, you may have issues with the **** falling into the halfcock notch. There is no fly in that lock.

I've already taken it down quite a bit, over 1/32nd of an inch, and it's still so strong it's hard to ****.
Back to the sander

 

[deerstalkert]

Sudsy, have you polished the riding surfaces of the tumbler and the inside of the ****? these may be adding to the difficulty in cocking the lock.

 

[Sudsy]

Sudsy, have you polished the riding surfaces of the tumbler and the inside of the ****? these may be adding to the difficulty in cocking the lock.

Not yet
I'll work on that tonight

 

[M. De Land]

Not yet
I'll work on that tonight

Is the back of the spring scrubbing against the lock plate any where?

 

[smo]

Check the lock plate for straightness…

If the lock screws have been overly tightened binding could happen …

Several moving parts that could come into play..

I thinned the spring on a Spanish made pistol and it helped tremendously..

I was told too only remove material along the long leg of the spring , and that’s what I did.