How to fix frizzen backlash

[Rich]

I have a large siler lock (not a chambers). The frizzen has a backlash problem. The recent Muzzleblast suggested extending the leather/lead holding the flint forward so that the frizzen hits it, rather than the flint. While that may work, it feels like putting a sticker over the check engine light. The frizzen spring seems firm enough, but maybe I should reharden it. I was considering lightening the main spring. What do you think? How should the main spring and the frizzen spring be balanced (if at all)?

[mattdog]

Just my experience with rebounding here.  I can almost always trace it back to the frizzen spring and have fixed several with a stiffer spring.

Sometimes something as simple as a shorter fint wil make a difference.  

Barring that, if you are willing to re harden/temper that spring while you are at it put a small bend down(10 degrees + -) at the end where the toe of the frizzen will rest when the frizzen is full open.  This helps to "catch" the frizzen in the open position and makes a tad harder for it to snap back aganist the tension of the spring.  Pay attention here 'cause if you bend it too far the spring won't come up far enough to keep tension on the toe while open.  Bend it just enough, don't go too far.  While it is hot open it (a little bit) for preload.  This way it will be stronger but you don't have to mess with a cooler temper temperature and risk breaking it.  Harden and temper as usual.

  As a last resort you can shorten or bend the frizzen stop (the pig tail poking out in front of the frizzen) up so the frizzen travels slightly farther open.  

[rich pierce]

What I am about to say is mostly theory.  I have not had the opportunity to play around that much with these variables, but have found them important in tuning some locks to work.

1) The cam shape on the frizzen teat impacts the power required to get the frizzen to open and, in the same way, prevent or not prevent rebound.  I have had to alter this shape to get some frizzens to open reliably, and that tells me the shape of the cam matters.  The more V shaped it is, the less force would be required to start the frizzen opening, then the force would ramp up fast as the tip of the V begins to ride onto the frizzen spring.  That is not what we want, as the frizzen must stay closed until fired, and definitely open.  So on the working side of the cam that controls opening, I think we want a rounded shape for relatively even force through the first 30 degrees of opening.  Then the cam shape should decrease the resistance to the frizzen opening when the flint reaches the bottom of the frizzen face.

OK so the other side of this is the shape of the cam on the "rebound" side.  Ideally the can should provide resistance from the beginning of the rebound, and not let it get a head of steam.

2) How and where the curled "stop" contact the frizzen spring and how far it allows the frizzen to open can also affect rebound by the principle of lever.  Seems to me the further away the curled tail strikes on the frizzen spring from where the frizzen pivot rubs, the more leverage it would have for rebound.

These are idle theories unsupported by actual data.

[Darrin McDonal]

This is interesting that you mention this because I have been having this same issue with a couple of the same locks. It was a real problem ( 5 strikes to destroy the flint)when I first started the test firing of the trade gun I recently finished so what I did was remove the spring and aneal it. Then, when it was all nice and cool I reshaped it to give it more upward pressure by giving it a little wider bend towards the tip of the spring. I then polished it and rehardened and tempered it. What happened was it helped 85 %. I am still getting the backlash but its taking more strikes to destroy the flint. I will repeat the process again soon to try to finalize the issue. Its one idea to toy with. As is any issue with these guns, there is 20 differant ways to do any job it seems. This is one approach. I would like to hear others myself.
Darrin

[Jim Kibler]

The big factor is spring pressure on the frizzen toe when fully open.  Also in terms of lock design, when a frizzen opens further (further from the cam over position) it is less prone to bounce back far enough to go over center.  So spread the spring to get more pressure.  Don't worry about either the mainspring or frizzen spring being too strong.  It's about impossible for such to be the case under normal circumstances.

[flehto]

I've had 2 Silers { one small and one large....not Chambers} that would rebound fully and the frizzen would sit  atop the flint. The fix was to open the frizzen to 30 degrees, mark the frizzen spring w/ the toe location and w/ the Dremel, grind a .010  high "hump" centered on the toe location. Polished  it well and that fixed the problem w/o annealing and rehardening the frizzen spring. The toe location can also be located on the frizzen spring by manually running the flint down to the bottom of the frizzen strike surface and making a mark. These old Silers didn't provide much leeway as regards flint length and when knapped too short, the frizzen wasn't rotated to the toggle over point. ....Fred

[eagle24]

There are some slow motion videos of flintlocks on youtube that are interesting and relevant to this discussion.  Several of them show the frizzen rebounding back into the flint on the first rebound.  All the ones that rebound all the way back to contact the flint appear to really compress the frizzen.  After watching those videos, I would guess that Jim Kibler is correct in his reply.  Not that I doubted you Jim!  It sure appears to me that the cause is related to a weak frizzen spring.

[Larry Pletcher]

Greg,
Those you-tube slow motion videos are mine.  There are more on my web site.  Before doing anything serious, I'd try about every possible combination with flints closer to frizzen, farther away, bevel up and down.  All of these flint positions affect timing.  Once you rule out flint positions, then try the good advice listed above. 

Keep in mind that ALL frizzens rebound.  The only one we videoed that did not was one where the holder had his thumb between frizzen and spring - stopped dead still, pinching his thumb.  One with no frizzen spring gently rebounded once and stopped nicely above the pan. I also have videos of frizzens that made three trips back anc forth.

Regards,
Pletch

[Rich]

Problem resolved. I annealed the frizzen spring and spread it a bit wider, rehardened it and tempered it in the lead pot. Thanks to all who answered.