westrayer
40 Cal
T/C and Lyman produce their locks with coil springs while it seems that everyone else goes with leaf spings. What are the advantages of each?
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Coil spring vs leaf spring?
- Thread starter westrayer
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Coil wire springs are many times more reliable than are flat or V springs but the later give faster reaction (lock time). Also coil springs don't load up like flat and V as they are much longer (because of the coiling) and store energy over a longer power curve which generally means a smoother but slower power stroke.
I've converted quite a few flat spring actions to a strut and coil main springs and prefer them in some guns. Rolling block and Stevens 44s respond wonderfully to a strut and coil main spring.
I have taught myself to make coil springs in my lathe, cold winding them over a mandrel using the half nut and thread gearing to space the coils. It's interesting work and becomes very necessary when a small spring takes off across the shop into the nether world, never to be seen again.
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Hi,
Coil springs simply get stronger the further they are depressed so the force builds up during the entire cocking process. "V" springs, which have been used successfully for 5 centuries or more and are entirely reliable, can be designed and fitted such that the force needed to bring the lock back from rest to half cock is more than the force needed to bring it from half to full cock. In other words, it lets off a little allowing a lighter trigger pull. Coil spring locks usually feel rough and clunky and in most cases are fitted to set triggers so you don't experience a heavy trigger pull. You will find coil spring locks on mass produced muzzleloaders because they are cheap and easy to manufacture. High quality flint and percussion locks always have "V" springs.
dave
Coil springs simply get stronger the further they are depressed so the force builds up during the entire cocking process. "V" springs, which have been used successfully for 5 centuries or more and are entirely reliable, can be designed and fitted such that the force needed to bring the lock back from rest to half cock is more than the force needed to bring it from half to full cock. In other words, it lets off a little allowing a lighter trigger pull. Coil spring locks usually feel rough and clunky and in most cases are fitted to set triggers so you don't experience a heavy trigger pull. You will find coil spring locks on mass produced muzzleloaders because they are cheap and easy to manufacture. High quality flint and percussion locks always have "V" springs.
dave
I agree with the "cheaper to make a lock with a coil spring". When you look at those locks, there is only one screw that holds them on the rifle. That screw is placed in the center of the lock-plate. There's a threaded bolster in the center of the lock-late that won't allow the use of a flat spring.
A properly setup leaf spring lock will have a greater poundage pull from the rest, to the half-cock position. From the half-cock position to the full-cock position the poundage should actually be less.
On a properly setup leaf spring, when the hammer is pulled to full cock, the spring should be as close to the center of the tumbler as possible.
This is the geometry of a properly setup lock. When at rest the spring is at the bottom of the tumbler. When you pull the trigger to half cock the spring "rises the most". Then from half cock to full cock the spring moves very little. When a coil spring setup the poundage has to increase as the spring compresses more.
A properly setup leaf spring lock will have a greater poundage pull from the rest, to the half-cock position. From the half-cock position to the full-cock position the poundage should actually be less.
On a properly setup leaf spring, when the hammer is pulled to full cock, the spring should be as close to the center of the tumbler as possible.
This is the geometry of a properly setup lock. When at rest the spring is at the bottom of the tumbler. When you pull the trigger to half cock the spring "rises the most". Then from half cock to full cock the spring moves very little. When a coil spring setup the poundage has to increase as the spring compresses more.
Marc H
32 Cal
Interesting discussion. I have a Lyman Flintlock Trade Rifle with a coil spring. The lock works very well. The trigger seems to be nice, although not as good as my M1 Garand.
My question is ; did the original lock designers use a leaf spring because of the variable strength over travel vs the coil spring constant strength or was the leaf spring used just because it was what was available?
Marc
My question is ; did the original lock designers use a leaf spring because of the variable strength over travel vs the coil spring constant strength or was the leaf spring used just because it was what was available?
Marc
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Phil Coffins
69 Cal.
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Whats increasing is the leverage as the cock is drawn further back but the energy load and tension is still sharply increasing into the flat or V spring. They are much shorter so the energy that is stored in them subtends less mass length which unloads and is transferred much faster to the work load.
I've made and replaced a lot of V, flat and coil springs in all manor of firearm and coils are probably at least twice as reliable as V or flat when made of good spring stock , well corner dressed and properly hardened and temper drawn. The only flat springs I have encountered on par with coil as far as reliability are when made of stainless spring stock.
Certainly some flat and V springs have survived for a couple of centuries but if both a non flawed coil and flat V spring were exercised the exact cycle count bearing the same load until failure the coil would win.
The problem with V springs is the tension loading in the vulnerable turn back and in flat springs the profiling where as a coil maintains the same diameter along it's entire length with no turn backs / profiling/shaping /narrowing thus evenly loading the entire coil.
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Erwan
45 Cal.
Yes, you're right, this one is by Leonardo da Vinci for a wheel lock pistol...
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Philip A.
36 Cl.
Coil springs are much easier to produce on a large scale, with close to no material waste, hence an order of magnitude cheaper.
The "let off" effect in a lock, i.e. the effort tu pull the cock diminishing as you approach full cock, is determined by the geometry of the tumbler and mainspring.
As you can see below, a properly designed tumbler and V mainspring have a much shorter lever/arm at full cock than at rest, meaning that you need less effort to move the cock near the end, since the mainspring is compressed over a shorter distance for the same amount of cock movement.
On a TC coilspring lock, instead, the arm length is basically the same at rest and at full cock, which makes the cock harder to pull the more the spring is compressed.
The "let off" effect in a lock, i.e. the effort tu pull the cock diminishing as you approach full cock, is determined by the geometry of the tumbler and mainspring.
As you can see below, a properly designed tumbler and V mainspring have a much shorter lever/arm at full cock than at rest, meaning that you need less effort to move the cock near the end, since the mainspring is compressed over a shorter distance for the same amount of cock movement.
On a TC coilspring lock, instead, the arm length is basically the same at rest and at full cock, which makes the cock harder to pull the more the spring is compressed.
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Simply put , leverage increase !
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Depends on the purpose, is one better than the other, only in the same application, I’d probably chose the V spring for a mainspring or sear spring etc.
In a receiver, rolling block, bolt, or extractor i would want the coil spring.
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No comparison for smooth function in a Roller or Stevens 44. A strut and coil main spring conversion is light years ahead of the flat springs they are designed with..
Marc H
32 Cal
Group,
Measured the force to move my hammer on a Lyman Trade rifle in 50 cal. This flintlock uses a coil spring.
From fired to half cock took 7 1\2 pounds. From half cock to full cock took 8 1\2 pounds. Spring scale was attached to the top of the flint jaw.
So, the force just increases as the coils are stretched (hooks law). I would be interested in the same measurements using a traditional flat spring with the curve on the spring end that changes the force relationship.
Marc
Measured the force to move my hammer on a Lyman Trade rifle in 50 cal. This flintlock uses a coil spring.
From fired to half cock took 7 1\2 pounds. From half cock to full cock took 8 1\2 pounds. Spring scale was attached to the top of the flint jaw.
So, the force just increases as the coils are stretched (hooks law). I would be interested in the same measurements using a traditional flat spring with the curve on the spring end that changes the force relationship.
Marc
Properly setup and tuned, the lever spring from HC to FC should actually decrease. When the "hook" on the mainspring almost touches the "inside" of the tumbler, that's setup right. So, when you look at the leverage from HC to FC, the spring compresses very little, if at all.
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