Bend the sear bar up?

[WonkyEye]

Update: got a very fast reply from Jim Chambers. His suggestion is grinding the bottom of the sear lever and noted its 2x as thick as necessary. He also said bending was ok and gave instructions to re-heat treat. Give that advice, and the large number of suggestions to grind, that is what I'll do.



This is my first build. Chambers Dale Johnson lock. The sear bar is so close to the edge of the lock plate 15/1000s, that I'm concerned. After polishing the edge of the plate it might even be even with the edge.

I'm thinking about bending it up 1/32" so it's not touching the wood. My hesitation is this lock works like a fine tuned clock, compared to my TC and my L&R it's a thing of mechanical beauty. I'd hate to cause a bigger problem.

I haven't inlet anything yet, I'm still working out layout and measurements. I'm taking my time and waiting for winter hibernation to really get going.

If I do bend, what's your tips for re-hardening and tempering the sear?

 

[wiscoaster]

Instead of bending, which I think is iffy anyway, and probably messes up your interaction with the trigger bar, it looks like you've got plenty enough material there to do some filing to give you a little more clearance.

 

[Phil Coffins]

I’d start by contacting Chambers and explaining the issue. They would be best qualified to answer any questions you have.

 

[wiscoaster]

Ya, that's an even better idea.

 

[Phil Coffins]

Move the hammer to half cock and the sear will probably be below the edge of the plate.

 

[ZUG]

If you do bend the sear bar you don't need to reharden it. The only reason that the whole sear is harden is because of the way they are manufactured. When made the whole sear is harden and tempered because it is easier to do it that way then to just harden only the nose of the sear. There is ample amount of steel in the sear bar that it will not deform from the action of the trigger and if you think you will wear the sear or trigger bar think again - it would take MANY years for that to happen. The only thing that you MAY notice is a rough trigger pull but not much if at all. That trigger bar is still hardened. There is not much movement between the sear and trigger bar so very little wear is between the two surfaces.

I've done a lot of "tweaking" on sear bars to give me more clearance (Clarence ). Do as Phil says to check if the sear drops below the plate when in full cock position if so call Jim Chambers.

 

[FlinterNick]

This is my first build. Chambers Dale Johnson lock. The sear bar is so close to the edge of the lock plate 15/1000s, that I'm concerned. After polishing the edge of the plate it might even be even with the edge.

I'm thinking about bending it up 1/32" so it's not touching the wood. My hesitation is this lock works like a fine tuned clock, compared to my TC and my L&R it's a thing of mechanical beauty. I'd hate to cause a bigger problem.

I haven't inlet anything yet, I'm still working out layout and measurements. I'm taking my time and waiting for winter hibernation to really get going.

If I do bend, what's your tips for re-hardening and tempering the sear?

Why would you bend it? Its where it is designed to be on the plate, the trigger contact is close, bending the sear will put it further away

 

[Larry (Omaha)]

Why would you bend it? Its where it is designed to be on the plate, the trigger contact is close, bending the sear will put it further away

For the sake of discussion and not argumentative. A sear below the plate causes issues when replacing and removing the lock.
What difference does it make if the sear is farther away from the trigger contact? A trigger bar has to fit the situation. (add or shorten hight of the bar) More thought please.
Larry

 

[FlinterNick]

Doesn’t look like it’s off the plate.

No issue

 

[FlinterNick]

For the sake of discussion and not argumentative. A sear below the plate causes issues when replacing and removing the lock.
What difference does it make if the sear is farther away from the trigger contact? A trigger bar has to fit the situation. (add or shorten hight of the bar) More thought please.
Larry

Regards to the sear being further … you’ll have a dangling trigger. When I build I try to fit the trigger so contact is close almost self setting

 

[Larry (Omaha)]

Regards to the sear being further … you’ll have a dangling trigger. When I build I try to fit the trigger so contact is close almost self setting

What is a dangling trigger? The bar needs to be as close to the sear as possible and maintain a free moving sear.
Larry

 

[garypl]

I had a Siler lock with the sear bar right at the edge - about the same as yours. I just cut a clearance notch inside the lock mortise and it went in and out of the lock mortise with no problems.

 

[EC121]

Silers(the Dale Johnson lock is a modified Siler) are made that way. You won't file anything off that hard metal, but since there is plenty of metal, a little judicious grinding will help you clearance.
For a bit of background. Dale took a Siler lock and sawed the plate almost in half. Then he bent the tail down about 1/8" to allow the tail to follow the wrist better, and welded the plate together. This along with undercutting the breechplug lug helps avoid the infamous humpbacked wrist. Jim then took the modified lock and used it to make the mold masters for casting.

 

[Tumbledown]

For the sake of discussion and not argumentative. A sear below the plate causes issues when replacing and removing the lock.
What difference does it make if the sear is farther away from the trigger contact? A trigger bar has to fit the situation. (add or shorten hight of the bar) More thought please.
Larry

How is the sear at half cock? You might have no issue removing and replacing the lock that position.

 

[ChuckJonesWagon]

Silers(the Dale Johnson lock is a modified Siler) are made that way. You won't file anything off that hard metal, but since there is plenty of metal, a little judicious grinding will help you clearance.
For a bit of background. Dale took a Siler lock and sawed the plate almost in half. Then he bent the tail down about 1/8" to allow the tail to follow the wrist better, and welded the plate together. This along with undercutting the breechplug lug helps avoid the infamous humpbacked wrist. Jim then took the modified lock and used it to make the mold masters for casting.

Agree. A bit of grinding will give you the clearance you’re looking for.

 

[ronaldrothb49]

It is where it was designed to be Don't mess with it. Jim designed this one so that the sear bar will be in the same place regardless of where the hammer is. Even the new Siler's use this type of tumbler and sear so you no longer have to worry about the sear bar dropping below the edge of the plate.

 

[Larry (Omaha)]

How is the sear at half cock? You might have no issue removing and replacing the lock that position.

A possibility on the half cock, but read Phil at 10:15 am
For simplicity, a lock that can be removed and replaced without extra motions is a plus to me.
Thanks
Larry

 

[WonkyEye]

How is the sear at half cock? You might have no issue removing and replacing the lock that position.

Good call. Half cock gets me a bit of extra clearance, 15/1000" uncocked, 25/1000" half cocked, 35/1000" full cock. That makes me feel better. My concern was wet wood swells, and might mean full cock doesn't catch because of contact with the wood or worse, just barely and shaking or bumping is enough to set it off.

Combining all of the above advice this far:
1. I did email Chambers the pics and ask for thoughts. I'm assuming I've just offended Mr. Chambers, or annoyed him because it's probably meant to be like that. If I get a response I'll follow their advice.
2. Combining several suggestions above, the sear bar is 1/16" thick, I could probably remove half of it and still have plenty of strength, but I think 1/64" is plenty. If I need more I'll undercut the mortise and make a notch for clearance.


Regarding sloppy triggers, my triggers have way too much metal, I will be grinding away a lot of it, if I don't the wrist will be thick, about 1.75" where the tang bolt goes through to the lock plate. The original JP Beck I'm trying to loosely follow is 1.625" in that dimension. Grinding a 1/32 of the sear bar gets me 1/4 of the way there.

 

[SDSmlf]

Half cock gets me a bit of extra clearance, 15/1000" uncocked, 25/1000" half cocked, 35/1000" full cock. That makes me feel better. My concern was wet wood swells, and might mean full cock doesn't catch because of contact with the wood or worse, just barely and shaking or bumping is enough to set it off.

I would suggest NOT bending sear bar, only potentially creating a real problem. As long as sear is inside the lockplate you are good to go, just remove enough wood inside the mortise to allow clearance at all sear bar positions.

Worried about the wood swelling from moisture, apply a sealer to the wood. If you insist on doing something, maybe stone a few thousandths off the bottom of the sear bar, but still have to ask why.

Here is a RE Davis lock, maybe .025” clearance at full cock. Doesn’t touch the wood in the mortise, as the wood has been carefully cleared out.

 

[WonkyEye]

I would suggest NOT bending sear bar, only potentially creating a real problem. As long as sear is inside the lockplate you are good to go, just remove enough wood inside the mortise to allow clearance at all sear bar positions.

Worried about the wood swelling from moisture, apply a sealer to the wood. If you insist on doing something, maybe stone a few thousandths off the bottom of the sear bar, but still have to ask why.

Here is a RE Davis lock, maybe .025” clearance at full cock. Doesn’t touch the wood in the mortise, as the wood has been carefully cleared out.
View attachment 363211

You're sort of making my point, that's huge compared to what I have. if I had that much space I wouldn't have made this post.