Frizzen Hoping or Skipping

[kyridgerunner]

After reading Fred Stutzenburger's article in this Februarys Muzzle Blast magazine I tested all six of my locks and found that 4 out of the 6 I own do, in fact, hop. That is to say - the flint skips a spot as it scrapes down the frizzen face. It didn't matter if the flint was bevel up or down. Each one skipped about 1/4 inch on average. It's a very simple test to do and I'm surprised I haven't seen a reference to this before. Anyway - does anyone know an easy fix for this. I'm pretty sure a well tuned and properly designed lock should not do this. The two locks I tested that do not skip, or hop, whichever you want to call it, are what I'd call my least expensive and/or oldest locks. One is marked " made in Italy" the other is a 50 year old Russ Hamm. So- what's going on here?   

Stutzenburger stated that a weak frizzen spring may be the problem. Two of the locks I tested are new Chambers Silers. I'd think the springs on those should be correct. Does anyone know what the ratio between the Main and frizzen springs should be? I've read somewhere that the frizzen spring should be 1/3 the strength of the main spring. If that's true then none of the locks I own have the correct spring strength.

Anyone have any insight into this. Any suggestion constructive comments appreciated.

[EC121]

It also depends on the angle the flint hits the frizzen, and probably the shape of the flint itself.  Too sharp of an angle and you get a chop instead of a slicing action.  Then the frizzen moves away from the flint until it catches up and hits again.  Try shimming the back of the flint up a little to lower the strike angle.  It doesn't take a lot.  With the proper strike angle the spring strength isn't critical.  A round bottomed flint might also cause a sharp strike angle.

[kyridgerunner]

Thanks for the reply EC121. I tried changing the angles on two of those locks. It didn't make any difference except to change the location of where the skip was slightly. Also tried slightly longer and shorter flints. No difference really. I measured the frizzen and main spring strength with a trigger pull scale and those seem to be in balance. I'm kind of at a loss. I asked Chambers and L&R the question but so far no answer from them.

Is that EC121 in reference to the Super Connie's used in Nam? We had one crash and burn at Korat right in front of the Air Rescue Det. Our chopper saved a few lives on that one.

All the best and thanks again.

[EC121]

I was in Korat for 60 days about 71 or 72, but we didn't lose any.  I was on the radar bird EC121Ts not the intel type EC121Rs.

   You may also have to adjust the distance of the flint from the frizzen.
     If the frizzen snaps open at about 30-40deg., and the flint ends up pointing at the center of the pan, you should be OK..  If the locks work OK and puts sparks in the pan, don't worry about the skipping.  I have, on occasion, had a flint that seemed too sharp, and it hung up until it dulled some.

[kyridgerunner]

EC-121

I have changed the flint length and still have the skip.  My real objective is to see why this happens with some locks. Obviously a flint that scrapes all the way down the frizzen is going to throw more sparks and also probably last longer then one that hits then skips a sizable area of the frizzen. There must be a reason for this. Could be improper geometry, maybe the arc in the frizzen face doesn't match the arc of the flint tip, maybe spring tension. If I could figure it out then I could correct it - maybe. Don't know. All locks don't do this. I have a couple older locks that don't ship or hop which, to me anyway, points to something being different about the ones that do have a hop. I don't have the equipment needed to make precise measurements to check all the angles.

Thanks for the response. Take care and stay safe.

[Daryl]

I've not had a lot of flintlocks, but the ones I have all get scraped from the initial contact, right to the bottom.
After lots of use, the initial struck area is slightly gouged more deeply than the rest. Is this what you are referring to as hopping?
Are you saying that there is a skipped spot on the frizzen that doesn't get scraped?

[kyridgerunner]

Daryl,

Thanks for the reply. One of the locks is a brand new Chambers Small Siler. I just put it on a new rifle I built. The others are older locks but don't have more than a few hundred shots on them. All do the same thing. You can see where the flint first hits the frizzen, then it skips about 1/4 inch, hits again and them scrapes on down the frizzen. (Paint the face of your frizzen with a magic marker if you want to try this)  As suggested by EC121 I've tried this with bevel up, bevel down, different length flints etc. No difference. I also made a video using slow motion and then slowed that down even more using a phone app. It's not stop-action of course - but I could not see any evidence of the frizzen going forward on the initial strike and then bouncing back. Any ideas?

[rich pierce]

If a lock sparks reliably I don’t worry too much about whether I’m getting a clean smooth slice on the frizzen. In my fastest lock the flint jumps a little after initial strike. The frizzen is through-hardened. Every 10 years or so I give the frizzen face a light touch on the grinder when stripping the gun down, including breechplug.

[JHeath]

I'm no lock expert. But if you remove the springs and s-l-o-w-l-y swing the cock/flint across the frizzen and it does not scrape all the way down, the geometry is off. If it *does* scrape all the way down, then the problem is associated with speed. That means the frizzen is being accelerated and the inertia is carrying it forward just enough to break contact with the flint. Depending on the geometry, the flint might regain contact below that point not because the frizzen rebounds, but because the curve of the frizzen face combined with the radius from the frizzen axis produces harder contact below the "hop". So if the "hop" breaks contact by 0.001" when the frizzen accelerates, the curve of the frizzen might regain contact without the frizzen rebounding by 0.001" .

[kyridgerunner]

Reply to Rich Pierce:   I agree and thanks for the reply.  The locks do throw good sparks, especially the small Siler, and I'm shooting it a couple of a times a week. It's just that I like to tinker, plus when things aren't quite right, could perform better so to speak, I like to find out why and fix them. Also, when I pay top dollar for any product I want it to perform at it's very best. If the flint isn't scraping all the way down, as it's supposed to, then obviously it isn't preforming at it's best.

Reply to JHeath. That's an excellent observation and explanation of what's possibly causing the hop. I'll remove both springs and check the contact between the flint edge and frizzen through it's full travel. Best I can measure with a trigger pull gauge the SS lock frizzen breaks at 3 lbs and the cock at about 10 lbs. On my Russ Hamm lock ( which does not have frizzen hop) the frizzen breaks at 2.5 lbs and the cock at 12 lbs. That's contrary to what I'd expect and adds to my confusion.  Thanks for the reply and your input.

[Daryl]

Thanks for the clarification, kyridgerunner. Sorry I do not have a solution for you.

[kyridgerunner]

Reply to JHeath

I removed both springs as you suggested but using that method didn't really shed any light on what's causing the hop. Being as I'm physically holding the cock and the frizzen together throughout the complete cycle they stay in contact. It was certainly worth trying so thanks again for your help.

[smallpatch]

Ky,
Perhaps you’re over thinking this?
If it goes bang quickly, who cares if it skips a bit.?
You’re talking  about a piece of steel, and a rock. Neither are exactly machined, mated surfaces. These are 300 year old technology. If it works as intended, leave it alone.

[JHeath]

Reply to JHeath

I removed both springs as you suggested but using that method didn't really shed any light on what's causing the hop. Being as I'm physically holding the cock and the frizzen together throughout the complete cycle they stay in contact. It was certainly worth trying so thanks again for your help.

I think what has to mean is that the frizzen is moving away from the cock enough to create a gap. The tip of the flint swings a constant arc. The point of contact on the frizzen does not. It is curved, plus is being rotated away from the cock. So whatever is happening is a result of how the frizzen is moving.

If the "hop" section was a depression on the face of the frizzen, you'd expect the flint to hop over that depression. But that's presumably not the case or you would have noticed it when you removed the springs. More likely the cock is pushing the frizzen forward on impact like it's supposed to, and at some point the frizzen is moving forward on inertia causing the flint to lose contact. I've seen slo-mo video of locks where the cock swings down fast but shortly after contacting the frizzen it slows considerably. The flint is not swinging down as fast at that point, but the frizzen is still popping forward under inertia. I'm just guessing, but it sounds like what is happening with your lock is that the impact of the cock is accelerating the frizzen forward, and slowing the cock. At some point the cock is not coming down fast enough to maintain contact with a frizzen that is basically jumping out from under the flint's path. When the flint loses contact, there's nothing slowing the cock anymore, so it speeds up and catches up with the bottom of the frizzen.

That's just educated guesswork.   

[kyridgerunner]

JHeath:  That's as good an explanation as I can come up with. I'm hoping to make it to Friendship this year for the first time. Maybe I'll take that lock along with me and see if any of the lock makers can point to a specific reason for locks "hopping". As I'd mentioned before, all three of the locks that "hop" are on rifles I shoot pretty regular. Thanks again for your help and insight.