Frizzen spring tension ?

[Steeltrap]

I've measured the Frizzen tension using a Lyman electronic TP gauge. To open the frizzen takes about 4.3-lbs. Now, when I cock the lock and hit the sear bar, the frizzen opens every time properly.

What I'm concerned about is the lifespan of flints. I would think if the frizzen opens easier, the flints would last longer.

So, if I need to lessen the poundage, I believe I would need to remove some of the flat part of the frizzen spring. The spring is hardened\tempered right now.

I've checked the frizzen and it opens\closes freely when the spring is removed with no binding at all.

Any thoughts\advice on this?

[wmrike]

I've never thought about it in terms of numbers, so I checked.

My most used lock is a 20-year-old large Siler.  I always thought the Silers used pretty stout springs.
 Measuring the pull at the very top of the frizzen, I get 3.5#.  Without trying them all, I think that's the stiffest frizzen I play with.  I'm disappointed if I don't get 125 strikes from a flint with that lock.  I had one flint go 215 before it split lengthwise.  Certainly beats caps, eh?

Be interesting to read what others experience.

[Steeltrap]

I may have arrived at my own conclusion. I polished up both the spring contact point and the frizzen contact point using 400 grit. I applied a drop of oil and I’m now at a consistent 2.3-lbs.

[Blacksmoke]

The late John Bivins had a formula for mainspring vs. frizzen spring tension. Frizzen tension = 1/2 of ms tension.  In other words if it takes 15lbs. of pressure to pull the cock off of "full forward", then the poundage to open the frizzen is 7&1/2 lbs. 
I have always subscribed to this formula for any of my rifles or restorations.   Hugh Toenjes

[Kevin Houlihan]

So, if I need to lessen the poundage, I believe I would need to remove some of the flat part of the frizzen spring. The spring is hardened\tempered right now.

  FWIW - Even with th spring hardened and tempered, you should still be able to file the spring if need be. 
Kevin

[Steeltrap]

I haven't measured the poundage of pulling the hammer to full cock. I'll give that a go and see where I end up.

BTW, when I do these measurements I have the lock secured in a vise with no obstructions to anything that moves.

[Blacksmoke]

Steetrap:  No need to pull the cock to full cock.  Just use a small fish scale and measure the poundage pull of the forward rest. If you went all the way to "full cock" check to see it the poundage increases or decreases at full cock.  If the poundage increases towards full cock then the geometry of the mechanism needs attention. The cock should always loose tension as it moves to the full cock position.  Then use the same method to measure the poundage it takes to pull the frizzen just off of the closed position.  Hugh Toenjes

[Steeltrap]

Steetrap:  No need to pull the cock to full cock.  Just use a small fish scale and measure the poundage pull of the forward rest. If you went all the way to "full cock" check to see it the poundage increases or decreases at full cock.  If the poundage increases towards full cock then the geometry of the mechanism needs attention. The cock should always loose tension as it moves to the full cock position.  Then use the same method to measure the poundage it takes to pull the frizzen just off of the closed position.  Hugh Toenjes

Thanks!  I'll measure from "full rest" to half-cock. Then half-cock to full and see what I get.

[Bob Roller]

If the file slides along the length of a mainspring.get a new sharp file or retemper that spring.Beveling is more decoration than benefit but it is common on the high end locks of Brazier and Stanton and not hard to do.
Bob Roller

[Steeltrap]

As measured with a Lyman Digital…from rest to half cock 10.2-lbs. From half cock to full cock 10.1-lbs.

A file run across the mainspring cuts into it well.

Also, before I do any else I will polish up the plate tumbler hole, and the tumbler as it has some machine marks on it.

BTW, this is a Dixie Gun Works lock that has Italy stamped on it as well.

[Steeltrap]

Disassembled the lock to examine and began clean up. The rear bridle screw (as I find most) could be tightened down to the point of locking up the sear. I cut and threaded a new screw so when it’s tight the sear bar is still free.

Still some more polishing to do before I reassemble and check draw weight again.

[Steeltrap]

I took a file to the lock plate (inside for now) and determined the tumbler was sitting "lower" in the lock plate. I did some filing to bring it all on one plane...I'm almost there.

Now when I assemble it and pull to full cock, I have just a tiny piece of the mainspring (right near the tumbler) rubbing against the lock plate.

I have a small gap between the mainspring and the lock plate from the back to just that spot near the tumbler.

Where the mainspring rest on the tumbler appears to be "square" to the axis of the tumbler so I don't think it's pushing the spring into the lock plate.

I'll take some more time to "flatten" the entire inside of the lock plate with a file and see where it takes me.

[Steeltrap]

Sometimes I have these "brain locks".....

I have two other flintlock rifles and one pistol.  Hey....why not measure those and compare to this lock?

Rifle #1:  Frizzen spring-1.1-lb.,  To half-cock 8.0-lb., half-cock to full-cock 9.1-lb.
Rifle #2:  Frizzen spring-2.88-lb.,  To half-cock 8.5-lb., half-cock to full-cock 9.5-lb.
Pistol:      Frizzen spring-1.2-lb.,  To half-cock 6.14-lb., half-cock to full-cock 7.15-lb.

This future pistol lock: Frizzen spring-2.3-lb.,  To half-cock 10.2-lb., half-cock to full-cock 10.1-lb.

The frizzen spring is acceptable. But I believe the mainspring is to heavy and will result in short flint lives.

So my question is (again I think) should I look to thin the mainspring little by little to get the poundage down?  And I would think I need to thin the bottom (longer) part of the spring in order to accomplish this?

Thanks.

[Blacksmoke]

Steeltrap: Sounds like to me that all of your locks are out of adjustment.  Traveling to full cock the cock poundage should decrease .and not increase or stay the same!  The placement of the mainspring can be changed to accomplish this .on most locks. It all has to do with "MA" mechanical advantage" on the tumbler. The hook of the mainspring should ride into the axel of the tumbler as far as possible and thus reduce the cock poundage. Also this will reduce
the pressure on the nose of the sear thus reducing it's function and wear. Historically speaking this is the way locks were originally made by and large.  Hugh Toenjes   

[Steeltrap]

In reading my Grenville chapter on locks, it states the poundage from half to full should go down. It has a hand drawing of how the tumbler should look (they all "look" the same with the exception of the stirrup models) but there's no instructions (give aways of the top secret how to's) on correcting the shape of the tumbler to allow for a decrease in poundage, nor any suggestion as to either modify a spring, or show the correct length of the mainspring.

So, it's sort of like..."That's not right and we will see you again sometime".

[Blacksmoke]

It's not so much the shape of the tumbler as it is the position of the hook of the main spring on the shoe of the tumbler. Generally speaking the main spring needs to moved back a little bit so the hook can get closer to the center of the tumbler.
I have done this procedure many times. It means drilling a new anchor hole for the mainspring anchor pin and filling the old hole in. Also sometime you have to modify the other anchor point under the bolster of the lock plate as well. Hugh Toenjes

[Steeltrap]

Ahhhhhh…..that makes sense. Thank you!!!

[Steeltrap]

I had some time so I began to look at the lock again.

I studied how far the MS was going up\towards the tumbler and it appeared to be "up there pretty good".

So I took some marker and marked up the spring end and also the tumbler. To my surprise when I pulled it to full cock, the top of the spring would "mash" or touch the round part of the tumbler. No wonder the poundage went up when going from half to full.

So, I took my time and filed off the top of the spring where the marker showed where the spring was hitting the round part of the tumbler.

After filing down enough of the spring, I then sanded it up to 400 grit polish. My poundage from rest to half-cock is 10.1-lb average. Now from half-cock to full it's 9.0-lbs.

From everything I've read use of the lock may bring the poundage of the spring so I'm not going to do anything else to fool with the spring tension.

I'll have to take some time and look at my other locks to see what's up with them.

Thanks for the post. All very helpful.