Tig and Re-drill and tap?

[Steeltrap]

I screwed up the top bridle threaded hole on a small Manton. Moral of story is don't work in something when you are mentally fatigued.

I looked at the possibility of doing a thread insert https://www.mcmaster.com/products/adapters/thread-size~6-32/18-8-stainless-steel-easy-to-install-thread-locking-inserts/ but the drill size needed is .182 and that is within ten-thousands of the edge of the lock plate. I fear to close. (I know the original thread is 6-40 and these inserts would be 6-32, but I believe that thread difference would still work....2 different screws)

I don't weld anything. I have an acquaintance that does. I understand that a TIG weld would fill the hole. After the weld is there anything special I would need to do to re-drill and tap?  Is there anything I would need to mention to the welder before he does this?

BTW, I just watched Jim's "fix" video here:  https://americanlongrifles.org/forum/index.php?topic=56945.msg569538#msg569538 I see that he used a screw to fill the hole of his customers mis-drilled hole.....but my question is could the hole be drilled in the same place again?  Or would the fix somehow cause issues when attempting to drill and tap again?

Thanks!

[Jim Kibler]

Yep, drill and tap right through the brazed in plug.

[D. Taylor Sapergia]

Is the machine screw also buggered?  If so, replace it too.

[Steeltrap]

Yes. I have a new one coming.

[Hungry Horse]

 Just drill it and tap it to 8-32 and ream out the hole to fit. An 8x32 machine screw is readily available.

Hungry Horse

P.S. you’ll never get the screws mixed up again.

[Gaeckle]

Just drill it and tap it to 8-32 and ream out the hole to fit. An 8x32 machine screw is readily available.

Hungry Horse

P.S. you’ll never get the screws mixed up again.

Hopefully there is enough meat around the bridal hole to accommodate the tap drill size and the clearance drill size.

I'd stick with a 6-40 and that uses  #33 drill, while the clearance is a #27. It will be tricky if using the bridle hole as a guide, use a drill press if you have one

[Bob Roller]

Ream the hole in the bridle to accomodate an 8x32 and retap the hole in the plate to 8x32.If you have a lath,a new screw cam be made to fit.
Bob Roller

[Dphariss]

I would not use a TIG. If ANY tungsten gets in the weld its going to be VERY, VERY hard.
 MIG works fine. But after welding a full anneal is a an option. Unless you are very confidant of the alloy of the part.

[Steeltrap]

Edit: In re-reading the thread, there isn't enough "meat" left on the bridle top to go to a size 8 bolt. I filed down the top of the bridle to give a little bit of lock plate edge to grab the inlet.

Edit: Since I've screwed the pooch on this one, I've decided to just sent it back to L&R. I called them this am and explained the issue. They will do their best to fix my mistake.

[Gaeckle]

Edit: In re-reading the thread, there isn't enough "meat" left on the bridle top to go to a size 8 bolt. I filed down the top of the bridle to give a little bit of lock plate edge to grab the inlet.

Edit: Since I've screwed the pooch on this one, I've decided to just sent it back to L&R. I called them this am and explained the issue. They will do their best to fix my mistake.

So....what was the mistake and how did it occur? Not that's important, but as a guide for others so they don't do the same thing

[Steeltrap]

My mistake was pretty easy to do when I get fatigued. (Don't do this when you're tired!!)

I was filing the lock bolt hole on the hook-breech in order to allow the lock bolt to be freely inserted in the hole I drilled\tapped in the bolster. For this small lock, and the "room" I had to work with, I installed a #6 lock bolt instead of a #8 bolt.

The bridle holes are all #6's as well. So I started the lock bolt into the bolster hole, then I could better see what part of the hook breech hole needed a bit more metal removed.

Unfortunately, instead of starting the 6-32 lock bolt in the correct hole (the one to the right in my above pic) I started it in the 6-40 thread bridle hole. And not only did I start it in the wrong hole, I took at least 3 screwdriver turns before realizing "why is this difficult to turn" and the light went off.

[davec2]

Just a thought, but there is no force to speak of trying to pull the bridle screw out of its hole when the lock is assembled.  A class 3A  thread fit is not required.  I would have just run a 6-40 tap through the hole to clear any interference for its 6-40 screw.  Unless the attempt to run the 6-32 screw into the 6-40 hole completely wiped out all the female threads, the re-tap would probably have been a sufficient fix.

[Steeltrap]

Thanks Dave2c. The issue is when I screw in the 6-40 bridle screw, the screw begins to go in straight, then goes on to a more "oval" screw in pattern. When screwed all the way in, the bridle hole no longer lines up with the plate hole. Thus, the tumbler and the cock are no longer 90-degrees to the lock plate. 

I hope I've explained that right.

[Jim S]

tig welding would work just fine. The "T" in tig stands for the tungsten in the electrode, not the material that is put in the weld. That is steel. A piece of flat copper is clamped on the back side of the hole, and the hole gets welded shut.
The only issue would be that the welded area might end up showing as a slightly different color in any blueing, browning, or polishing when it's done.

[P.W.Berkuta]

tig welding would work just fine. The "T" in tig stands for the tungsten in the electrode, not the material that is put in the weld. That is steel. A piece of flat copper is clamped on the back side of the hole, and the hole gets welded shut.
The only issue would be that the welded area might end up showing as a slightly different color in any blueing, browning, or polishing when it's done.

Nice explanation Jim S - sometimes people can get "confused" with some descriptions of a process. For me the process that Jim Kibler suggested is the simplest as this does not require a person that is a welder.

[Steeltrap]

Welp...L&R fixed the issue. I don't think they did more than re-tap the hole. However, a secondary reason I sent it back was the frizzen was not centered with the lock. They installed a new frizzen. Of course, now I have to re-polish the new one, but I don't have to be concerned with my existing inlet for the lock plate.

Turn around time was very fast. I shipped the lock out USPS ground on Monday....they called me Thursday telling me it was all fixed.