Lock Bolt Question

[JLayne]

All,
When I drilled and tapped the lock bolts on this pre-carve (my first), the rear bolt went in at an angle not the same as the forward bolt. Both are 8-32. Now when I install the rear bolt followed by the forward bolt, tightening down the forward bolt pulled the forward part of the plate inward and seems to put tension on the rear one, such that the original rear bolt broke off during disassembly. The pic below shows the angle. Is there anyway to correct the issue?  Thanks in advance.

[BarryE]

You could have someone weld the rear hole shut and re-drill the hole. Or simply relieve the hole in the stock and tang to take the pressure off the rear bolt and leave it as is.  If the bolt head is not 90 degrees to the face of the sideplate, it might be a problem with just opening up the bolt hole a bit.  Either way the bolt hole will be enlarged, and if that is unacceptable, it will be necessary to fill the gap by some method.

[smylee grouch]

You also might re-drill and tapp for a 10x32 making sure to get the hole straight.

[thecapgunkid]

smylee grouch...You also might re-drill and tapp for a 10x32 making sure to get the hole straight.

I did this once, and it worked just fine.  If your hole in the plate with the threads is off, you can make the same mistake again with the 10X32.  So put the plate in a drill press and get the lock plate hole right first.  Then clamp the lock to the stock and use the hole in the plate as a guide to go through the wood the right way.  Go slow, and let the drill do the work for you in straightening.   STOP at the tang, when you mark it and drill it separately.  Then put it back in the stock and finish drilling.

I don't know about your error, but mine was caused when I tried to drill through the stock and tang at the same time.  I ended up making the hole through the tang just a bit larger so the cross bolt made it through easier.''I think an approach like this may help you the way it did me.

[heinz]

It looks like your binding problem is occurring where the lockbolt goes through the hole drilled in the breech plug of the rifle.  Before trying anything else free up the hole through the wood and breech plug.  You can open the wood up to 3/16 and I would open the breech plug hole up to a 1/4.  You can then taper the lock side of the tang hole a bit more with a rat-tail file if you need to.  The Function of that bolt is to pull the rear of the lock plate in. It does not need to be tight in that hole.  It is good practice to avoid removing any more wood than you have too in that fragile area of the stock but you need clearance around the lock bolts.

[Eric Krewson]

I did that when I had a brain lapse and tried to drill the lock bolt hole through the breechplug and into the lock plate, things went badly.

[WESTbury]

When I was working in the machine tool industry designing machines, we once in a while had alignment problems with castings, even though they were machined. It was not always possible to open up the clearance holes for the bolts, so our toolroom would relieve the shank of the screws down to just below the root diameter of the thread. #8-32 is a rather small dia thread but the thread depth is not very deep. It's a cheat, but it worked.

[Jim Kibler]

Another option is to thread a bolt in the hole and silver braze it in place.  This in conjunction with peening makes a good repair. 

Jim

[Herb]

That isn't much of an angle. Hard to believe a bolt would break instead of bending.  I'd take a small round needle file and file the rear hole to the rear, large enough for a No. 21 drill to clean up.  Then I'd clamp the lock plate in place and tap with a 10x32 through the stock and fit that lock bolt.  And if there is still a problem, and there should not be, bend the lock plate.  Hawken rifles with 1 1/8 inch barrels have the lock panels tapered, wider across the front than the rear,  to make a narrower wrist.  This can be accomplished by filing a taper on the lock bolster.  Sam Hawken put that taper on the Jim Bridger Hawken lock plate by bending the tail of the lock plate inward.  Does your lock bolster lay flat against the barrel?  Is there a pivot point in the inletting to allow the bending?

[Stophel]

I don't know how you managed to break the bolt, but the angles of the bolts are not your problem.  If the nose of your lockplate sinks in when you tighten the bolt, that means you have over inlet there.  Your lockplate should draw down tight and bottom out without sinking in anywhere, no matter how crooked your lock bolts are.  Looks like you need to cut and fit some wood to go in the front of the lock inlet, glue it in, and reset the lock.  And make sure that the rear of the lockplate is inlet properly, and draws up tight to the barrel (and bottoms out every where else) with only the rear bolt tightened up.

[WESTbury]

When all else fails, "precision" shim technology usually works.

[Long John]

J

I would just open up the lock bolt holes to give the bolt shafts a little wiggle-room.  From your photo you appear to have enough bolt remaining in the lock-plate to grab and remove from the front.  Then you can install a new rear bolt.   I don't make pre-carves but on my builds the rear bolt is always a #10-32 while the forward bolt is #8-32.   

Good luck

JMC
John Cholin

[Eric Krewson]

Make a BIG hole in the tang for your bolt to pass through, I don't feel like as standard clearance hole is big enough. Just a thought but it looks to me if you build a rifle with a standard clearance hole through the tang, finish the rifle and shoot it the recoil will settle the barrel back a bit and the lock bolt may make binding contact with the tang. Just a rookie thought that might be off base, or not.

[Mike Brooks]

I don't know how you managed to break the bolt, but the angles of the bolts are not your problem.  If the nose of your lockplate sinks in when you tighten the bolt, that means you have over inlet there.  Your lockplate should draw down tight and bottom out without sinking in anywhere, no matter how crooked your lock bolts are.  Looks like you need to cut and fit some wood to go in the front of the lock inlet, glue it in, and reset the lock.  And make sure that the rear of the lockplate is inlet properly, and draws up tight to the barrel (and bottoms out every where else) with only the rear bolt tightened up.

This is the man that knows the actual problem and the solution.

[JLayne]

Thank you all for the replies and advice. I see that there are two lines of thinking, the first being that oversizing the rear hole may solve the problem, the second being that I may have inlet the front of the lock plate too deeply, such that it is being pulled forward when the forward bolt is tightened, thereby placing a strain on the rear bolt. In truth, being a novice, I wouldn't be surprised if both were correct. So, I think I will remove the plate and open up the rear bolt hole a bit as you suggest, and reinstall to see what happens. Even if it doesn't solve the issue, a little extra wiggle room for the bolt shouldn't hurt. If that doesn't fix it, then on to correcting the inletting.

Now for the questioned that may get me banned from ever posting again. If it is an inletting issue, rather than creating slivers of wood to build up the forward end of the mortise and then re-working it back down, I have seen where people in the past have put acraglass at each end of the lock plate mortise to achieve, I suppose, solid contact on both ends. If anyone of you have ever done that, could you please offer some advice. I have some acraglass (green box, thick type) laying around, but have never used it. If I were to, my principle concern would be what to do with the forward bolt hole in the plate so as to keep the glass from getting in there and ruining the threads? I was thinking fill the hole with some clay and use plenty of release agent, but if anyone has done this before, I always like to hear from someone with experience in that sort of operation.

Thanks again for your help. I am developing something of a routine on here in which each Monday, I post a question about the mistake I made the day before (Sunday). I get help from those who know on here, then try and implement their advice on the following Saturday. Then on Sunday, I move on to a new step and the whole cycle repeats itself. Lol.

Jay

[rich pierce]

 Clay would work to keep acraglas out of the threads. The trick will be using the right amount of goo.

[Eric Krewson]

I use superglue and sawdust to fill small inletting errors that won't show. Put a drop of superglue down, sprinkle very fine sawdust on the drop let it set and file it down to where you want it to be. It will be rock hard and won't come loose, the superglue soaks into the wod first and adheres to it. You can make a bead of superglue or spread it with a popsicle stick before you sprinkle on the sawdust.

On my first build I put on 3 nose caps and butchered the inletting on each one to the point there wasn't much wood left, superglue and sawdust to the rescue.

[heinz]

I have used vaseline on the parts you do not want accru-glass to stick to and lightly put the front screw in place.  Rich's suggestion to plug the hole with clay would also work. Just a very small dab of glass will accomplish what you want.  You should fix the tang hole and the inletting both. 

[JLayne]

I use superglue and sawdust to fill small inletting errors that won't show. Put a drop of superglue down, sprinkle very fine sawdust on the drop let it set and file it down to where you want it to be. It will be rock hard and won't come loose, the superglue soaks into the wod first and adheres to it. You can make a bead of superglue or spread it with a popsicle stick before you sprinkle on the sawdust.

On my first build I put on 3 nose caps and butchered the inletting on each one to the point there wasn't much wood left, superglue and sawdust to the rescue.

I have heard of doing that in places like where there is a small gap between the edge of the nose cap and where it meets the forestock, but I never thought of building the sawdust up on a flat surface inside a mortise. I may give that a try if I opt against the acraglass.