Do all flint locks have bounceback?

[mjm46@bellsouth.net]

Didn't want to highjack LH's topic as this is a little different.

On the frizzen bounce back issue, I was wondering if all flintlocks have bounceback to some degree? I know of the trick of putting tape on the flint to see if it gets marked by a bounceing frinzen, but short of High speed photography is there a way to determine how much bounce a frizzen actually does have? And lastly is bounce actually a bad thing?

[Chuck Burrows]

Larry Pletcher's hi-speed camera shots of several different locks shows some bounce no matter what type/brand. His website is http://blackpowdermag.com/

He has posted them on youtube

[Larry Pletcher]

Chuck's right.  Of the 80+ locks we did video of, the only one that did not rebound was when David Price accidently dampened one with his thumb - pinched between the toe and the spring.  Some rebound 4-5 times; others only once.  Only a few came back far enough to touch the flint or top jaw.  We noticed that as flints became worn and were shorter, the frizzen rebounded a little farther. (We saw this in a lock that Lowell Gard brought.  We videoed his with a fresh flint and then did try 1, 11, 21, 31, etc.  As the flint wore down the frizzen came back farther but never touched. Exceptionally fine Late Ketland).

BTW - David P. volunteered to help me that first year.  I had mentioned that we probably should have the same guy prime each lock for consistency.  He agreed and said, "The  same guy should hold and set off the lock too.  And I'll do it."  He helped the whole afternoon.  His help was most valuable!  Thanks David.

Regards,
Pletch

[mjm46@bellsouth.net]

Thanks for the info. It seems it's just the nature of the beast.

[LH]

Pletch,  thats some interesting and informative stuff you've done and I've enjoyed your tests very much.  One thing that jumped out at me was when you said that some "perceived" slowfires were in fact not slow and some that seemed fast were in fact slower than others.  When I have experienced slow fires from bounce back,  I have never doubted that they were in fact slow,  but now I'm doubting my own perceptions.  If in fact a bounceback causes a slow fire,  what exactly is the function that causes it?  I mean,  once the sparks are in the prime nothing is going to slow it down then is it?  Can bounceback actually divert some of the sparks from hitting in the pan?   I've always wondered about that.   

[The other DWS]

Seems like, maybe, possibly, if, --- the timing was right, a frizzen popping back toward the closed position might actually help by containing some of the expanding flash and directing more of it toward the vent.  Imagine a frizzen so quick that it snapped shut and trapped ALL of the flash in the pan

oh well I need more coffee to finish waking up anyway.

[westbj2]

I happened to come across this photo.  Seems like a viable solution to frizzen bounce-back.  The screw adjusts the tension on the frizzen spring.   Apparently this bounce-back thing goes back at least to 1810!   
Jim Westberg

[mjm46@bellsouth.net]

Pletch
In all the locks that were tested was the bounce consistant within makes or did that vary?

[NSBrown]

Here's some speculation concerning a bounce back possibly slowing ignition:

If it is the heat of the flash (as I've read somewhere) that ignites the charge in the barrel (not an actual spark traveling through the touch hole)...then the close proximity of the frizzen and pan cover to the pan may absorb some of the heat of the flash...thus slowing fire.

[The other DWS]

Jim,  that Mortimer lock is really interesting.  Doesn't a frizzen spring usually have a peg up around the hairpin bend that in combination with a screw in the tail end locate the spring and holds it to the lock plate.  I'm trying to see how that one is anchored.  If it was mounted with the peg and the screw at the tail through the plate I don't see how the adjustment screw could have much effect on the flexing end of the spring. 

[Acer Saccharum]

I have thought that a frizzen that would bounce back and SHUT on the pan would force the fire into the charge faster....of course, you'd need a rebounding hammer.

Anybody want to build a lock to try this idea out?

Back in the heyday of flintlock development, maybe somebody tried this and it never took off. Industry focus shifted away from the flintlock two centuries ago, so I think we're on our own now. 

[westbj2]

I dont know what the back side of the spring looks like but only could offer some guesses.
I suspect the "teat" of the spring must be quite far forward on the lower limb or perhaps even just behind the bend on the upper limb.  There would be a number of ways to retain the spring keeping it up against the plate.  May be as simple as the tip of the adjusting screw riding in a mating cut in the stud.

Jim

[D. Taylor Sapergia]

I'd suggest that the adjustment screw has clearance in the spring, and threads into the stud above it.  The 'tit' will be on the lower limb in the usual place, allowing the upper limb to rotate about the bend while the lower limb remains relatively solid.  The adjusting screw threading into the stud is adequate to retain the spring.

[Larry Pletcher]

Pletch,  thats some interesting and informative stuff you've done and I've enjoyed your tests very much.  One thing that jumped out at me was when you said that some "perceived" slowfires were in fact not slow and some that seemed fast were in fact slower than others.  When I have experienced slow fires from bounce back,  I have never doubted that they were in fact slow,  but now I'm doubting my own perceptions.  If in fact a bounceback causes a slow fire,  what exactly is the function that causes it?  I mean,  once the sparks are in the prime nothing is going to slow it down then is it?  Can bounceback actually divert some of the sparks from hitting in the pan?   I've always wondered about that.   

I didn't mean to suggest perceived slow times were based on any lock querk.  It was just that the eye, ear, and mind aren't up to the job I expected my computer to do.  Invariably I would "guess" wrong.  Whether the time was .0350 or .0550 it all sounded like a quick snap. (BTW your ear is better than youre eye at this.)  The time had to be 45-50% slower before your senses could reliably guess right.

As far as rebound causing a slower ignition, I have no data.  I have not used video and computer timing on the same trial, and that would be needed for such an opinion. My unsubstanciated gut reaction is that rebound does not cause a slower time.  In all video, the sparks were in the pan long before the frizzen could rebound.  Once the sparks are in the prime, I believe two things effect pan ignition speeds. One is how many quality spaeks are in the prime and the ignition speed of the prime, (including grain size, etc.).

I seriously doubt that a rebounding frizzen positioned over the pan will be able to direct more fire into the vent, but again I have no data to rule that in or out.  We did have a Chambers round face lock that we videoed with NO frizzen spring. The frizzen rebounded gently and positioned itself nicely above the pan prior to the pan ignition.  When Jim saw this he remarked (with tongue firmly planted in his cheek)  that he worked hours to get the frizzen to behave that way.

Frizzens of the same lock style, from the same maker, generally behave the similarly.  I think this is mainly common sense.  Locks made from the same parts, on the same jigs, by the same hands are likely to behave the same.  If I watched video of 5 Deluxe Large Silers, as an example, I would expect similar rebound in their frizzens.  In fact, if 4 of the 5 behaved alike and the 5th one did not, you are likely to wonder what was different. 
Here is where the high speed video can be useful.  Imagine what we could learn by videoing a lock, doing a tuning step, and videoing again.  If I were a wealthy person, I'd love to do this sort of thing.  Because I'm not I have to rely on the generocity of the Olympus folks.  I'm about to bug them again.

Regards,
Pletch
Regards,
Pletch

[The other DWS]

I'm not sure of the nomenclature so bear with me on this. I'm trying to imagine the process in steps.

 On the frizzen below the pivot screw there are two protrusions.  one  at roughly 90 degrees rides over the bump on the tail of the frizzen spring (assuming a non-roller --small R of course--set op) this cams the frizzen open and shut. If I understand the dynamics the second protrusion as sen on the photo of the Mortimore lock serves as a stop, or shock absorber.
 As the hammer and flint hit the frizzen it pivots open the cam protrusion and the bump provide enough resistance to force the flint to scrape the frizzen face raking off the sparks and igniting prime and hopefully the main charge.
At this point the frizzen starts its solo dance. As the hammer and flint scrape down they pushes farther open,the protrusion over the top of the bump on the spring, and the frizzen spring snaps the frizzen open the rest of the way.
As its momentum carries the frizzen forward the second protrusion hits the frizzen spring which compresses serving as a shock absorber keeping the frizzen from slamming all the way open.  The compressed frizzen spring then would release it energy and attempt to force the frizzen back toward the pan-closed position.
 
If I have imagined and described this more or less correctly. This shock-absorber action is what you are calling "bounce-back"  It is obviously designed into locks that show the second protrusion or tail on the frizzen.  (it would be interesting to look at a historical progression of flintlocks to see when and where they show up in the evolutionary process)   It the frizzen is bouncing back too far/hard and hitting the flint, It seems to me that either the tail is too long compressing the spring too much on the shock-absorber compression, or perhaps the frizzen spring is too strong (perhaps to balance an overly strong mainspring)  or you have one of the rare elusive self-knapping flintlocks.

I think the "bounce back' is a designed in function and unless it is so great it is forcing the frizzen back and taking a second damaging whack at the flint it does no harm and is probably beneficial.   Obviously the flint length and position vis-a-vis the frizzen face and the mainspring energy are significant factors but overall it is a really marvelous piece of machinery that never ceases to fascinate me.

[Jim Kibler]

DWS,

I think it's better to look at the frizzen stop and it's action against the frizzen spring as being a consequence rather a designed in feature as you have suggested.   As the frizzen spring get stronger there will be less rebound or bounce back.  This is primarily because the force on the frizzen toe increases when the spring strength increases.  The key is to have sufficient strength in the frizzen spring and to have correct geometry in the frizzen and spring.   Under these conditions, bounce back will not be a problem.  And I'll say it again, I don't believe it's hardly possible to have an overly strong mainspring.  A lock properly designed and set-up will work fine even with very heavy springs.

Jim

[The other DWS]

Jim,  I currently have only three locks at hand to play with and one of them is brand new, needs some internal corrective work from the mfg. before I even try it with a flint, thought the frizzen set up is GREAT. 
None of them show any bounce-back visible to my eyes.  To all appearances they snap open and stop dead. all three show (using magic marker as a transfer dye) show very slight contact between the frizzen spring and the frizzen stop as the frizzen snaps over center. On only one, a smaller pistol-sized lock, can I force the frizzen farther open against the spring to any degree at all. on one I can move the spring, but just barely. The third I don't think I am budging at all--but the stop on it touches the spring much closer to the hairpin bend.  I wish I had checked them this way before blithering on


 "A lock properly designed and set-up will work fine even with very heavy springs."  I agree, assuming that you include properly balancing the springs as part of the "set up" process. 

[varsity07840]

I have an 1816 lock that gave me fits over the way it destroyed flints from bounce back. The mainspring was overly strong to the point that it took considerable effort to bring it to full cock and the frizzen was really pounded. I replaced the spring
with a lighter one and the problem went away. The stronger one was originally on a percussion conversion lock and I suspect it was made that way to ensure reliable
detonation of the musket cap.

Duane