screwed up tang bolt

[Black Jaque Janaviac]

Well OK.  First big booger-up on my gun-build.  

I was using that trick for center-to-center drilling to drill the tang bolt through the tang and into the trigger plate.  I drilled in from the tang-side first.  Then flipped it over and tried drilling the trigger plate.  I had used a punch to mark both spots, but the bit walked off from the mark on the trigger plate.  To make a long story short the threaded hole in the trigger plate is off axis.

Did I just make a pile of scrap metal and kindling?

[SingleMalt]

That can be fixed.  The trigger plate can be welded or replaced.  A hardwood dowel can be glued in to fill the hole in the stock. 

I've got you beat.  On an early build from a blank, I had so many lines drawn on the forestock that I couldn't tell which one was the correct one to cut.  Instead of sanding it off, and starting over, I picked the one I thought was right and cut.  That stock with my first hand cut barrel channel, went into the fireplace and I started over.

[B.Habermehl]

You have a couple of alternatives, one is live with it as it will be under the trigger guard bow and not be obvious ecxcpt to you.. Two is to clean and degrease the hole flux and solder a scrap bolt into the hole, file flush and punch deeply and redrill. BJH

[Black Jaque Janaviac]

I might glue a dowel in the wood hole and just punch another dimple farther forward on the trigger plate and redrill.  Would there be a problem with that?

The problem with just living with it as it is: the bolt won't start on the threads because the hole coming down through the wood and the hole through the trigger plate are off axis.

[Long John]

Like BJ said, you can salvage this if you choose to.

If you are using a #8 tang screw then you can re-drill for a #10.  I'm not going to assert that I am some kind of expert and  that I do it "right", but while I use a center punch to locate the hole on the trigger plate and a center pin to position the stock in the drill press I always drill from the tang down all the way to the trigger plate with a bit that is smaller in diameter than the tap size.  Once the drill bit gets to the trigger plate I remover the stock from the centering pin and finish the hole from the tang side of the stock.  I then switch bits to tap size and using the hole as a drill guide I open up the whole hole to tap diameter.  Then I remove the trigger plate from the stock and open the hole up to clearance diameter.  Then I put the trigger plate back in the stock and now use the clearance diameter hole as a guide for the threading tap.  This gets the hole in the right place on both the tang and the trigger plate and the threads lined up.  It sounds like a lot of work but it is a whole lot less work than fixing a screw-up!

So to fix your situation you can:
-install a well-fluxed threaded rod into your existing hole
-cut of the rod about .060 proud of the trigger plate surface, both sides
-peen the threaded rod well from both sides
-flow solder into the threads and file the surface flush
-re-centerpunch the location point
-reposition the stock on the centering pin on your drill press
-re-drill the filled trigger plate from the tang side to tap diameter for a tang screw of larger diameter than before.
-continue on like described above.

That's what I would do.  

As a general rule, remember that drills like to walk.  Professional machinists often use "centering bits" which are thick bits of drill rod with a small runty-short bit formed on the end.  These bits are super stiff and are used to just start the hole for an 1/8" or so.  Then the proper sized bit is installed in the drill press and the hole is deepened.  If you don't have centering bits slide your drill bit up into the chuck as far as you can so that only 1/8" sticks out of the chuck face.  Spot your hole with the short, undersize bit and then change bits up to your needed diameter.

That's all I know.  I hope it helps you some.

Best Regards,

John Cholin


re-

[D. Taylor Sapergia]

Simply centre punching and then drilling is what caused your problem.  After centre punching, and with the tang and the trigger plate out of the stock, use a drill press to pre-drill those holes well undersized.  Now you have a guide that your tap drill is going to want to follow, when you drill between centres.  As Rich has wisely advised, when you are between centres, drill from each side only half way with the tap drill.   Remove the trigger plate and drill down through the tang with the clearance drill bit.

In your botch, you have only said it is not centred well, but a picture would better describe how far off you are.  If it is only slight, I likely wouldn't bother, chalking this one up to experience, but if it's way off centre, then a patch and re-drill is in order.  Drilling a second hole either forward or to the rear of the old one is not the answer.  Your tang screw must pass through the tang at 90 degrees, otherwise, it will be cocked crooked and look aweful.  Drilling new holes fore or aft will make this happen for sure.  There is only one place for that screw to pass through the trigger plate, and that is ninety degrees to the tang.

[Black Jaque Janaviac]

If you don't have centering bits slide your drill bit up into the chuck as far as you can so that only 1/8" sticks out of the chuck face.  Spot your hole with the short, undersize bit and then change bits up to your needed diameter.

This.  I think this will help a bunch.

If it is only slight, I likely wouldn't bother, chalking this one up to experience, but if it's way off centre, then a patch and re-drill is in order.  Drilling a second hole either forward or to the rear of the old one is not the answer.  Your tang screw must pass through the tang at 90 degrees, otherwise, it will be cocked crooked and look aweful.

Duly noted.  Although the cocked crooked part may already be a reality the way it is - but nothing I can't live with.

The idea of soldering in a bolt segment is precisely the kind of stuff that makes this forum invaluable to newbies like me.

[oldtravler61]

Black jack you are so right. When in doubt ask. These people know so much an are so willing to help. I just hope that they know how much we appreciate all they do for us!!!!!!! Thanks to all of you!!

[Karl Kunkel]

After you peen the threaded rod and dress it smooth with a file the repair will be all but invisible. (not that I know from experience.)

[frogwalking]

I recently had the drill bit wander off the center punched spot on the tang of a buttplate. I could have had my son weld the hole in the buttplate up, but he was not available to do this. Therefore, I ordered a new buttplate, bought a new drill bit and did it again, this time much better.  Use a new, or very sharp drill bit, and undersized for the first try.  I now shore the entire rifle, stock, barrel and all in place on my bench and drill press to reduce the likelihood of error.  As noted, I still screw up occasionally, but not (badly) too often. 

[Long John]

Karl,

If the objective is just to hide a hole then there is no advantage to fluxing and  flowing solder around the plug.  But.....

In this case a replacement hole is going to be drilled and threaded which might (probably will) intrude into the plug.  I like to have a solder "adhesive" that will hold the remains of the plug in place if the replacement hole doesn't entirely remove it.  Learned that the hard way!

Best Regards,

John Cholin

[Black Jaque Janaviac]

When drilling between centers, how do you guys clamp your work?

The centering post I made sticks up several inches above the reach of my vise.

[jerrywh]

 you have been given some very good advice here from the guys. What Taylor says is the way I do it and it never fails. The problem you have is best fixed by welding up the hole and than re drilling it like Taylor described. However if you do not have the ability to weld it up plug the hole as some of the other guys suggested then -here is another option. Solder a  lug on the bottom of the trigger plate and thread the tang bolt into the lug. When you tap the lug do it through the tang bolt hole so that it will be in perfect alignment. The lug only needs to be about 1/4" high or less. After you inlet the lug you can drill the hole for the tang bolt hole as usual between centers. I hope This makes sense.
  Sometimes when I have a problem I just do something else for a couple of days and think about it. A answer will usually come to you after your mind gets a rest. Hurrying is what slows you down.

[Black Jaque Janaviac]

What I don't get about Taylor's advice is to drill the holes in the tang and trigger plate without them in the stock.  I understand from Taylor's post that the tang bolt needs to be perpendicular to the top face of the tang.  That is reasonably easy to achieve when it is outside the stock. 

However, the hole through the trigger plate doesn't seem to go through at a right angle.  How does Taylor get that angle correct when he drills it outside the stock?

I just tried Taylor's method.  And the tap drill can pass straight through from tang to trigger.  But when I run the actual tang bolt through it doesn't catch the threads.  Just to see what was up, I screwed the tank bolt through the trigger plate (upside down) and it was obvious the bolt was angled off-axis from the hole through the stock. 

[jerrywh]

 Your supposed to thread the trigger plate by putting the tap through the stock from the tang bolt hole with the tang and barrel  in place.

[Gaeckle]

Are you using a drill press or free handing this with a drill? A drill press makes all the difference.....at least to me.

[Black Jaque Janaviac]

Yep.  I am using the drill press (I am a newby to drill presses though, I only recently inherited this one). 

I did not cut the threads by running the tap through the hole in the stock.  Although when I test the length of the 8-32 tap it doesn't appear long enough to reach while mounted in the tap-tool.  I perhaps could put it through without the tap-tool and just use a small wrench or pliers to turn the tap.

[Keithbatt]

McMaster Carr sells long taps.

[Joe S.]

If you are not comfortable with your drill press you could use one of Dave Races drill jigs.As far as the long tap goes when you go thru your stock just get a thread or two started and then take it apart and put the trigger plate in the vise and finish it.Its a bummer when you break that long one off in the stock,been there.

[Black Jaque Janaviac]

". . . try and try again."

I finally got it!  After soldering in a plug, redrilling, and still not getting it threaded right.  This time I:

• welded that hole shut,
• re-drilled
• put the tap through the bolt-hole
• turned a few threads
• removed the trigger plate
• turned a few more threads
• BROKE THE !@#$@#^ TAP!
• realized I might have hardened the plate when I quenched it after welding
• annealed plate - let cool while I went to buy new tap
• came home and finished the job!