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Discussion Starter · #1 ·
I'm beginning to think that this barrel hates me. Started life as a half scale Napoleon with a 2 1/4" bore but decided I would feel a lot safer with it being reduced to a golfball bore. A reduction liner with it's own substancial breechplug was soon fabricated. The first attempt to epoxy it in place was almost disasterous... air trapped between the reduction liner and the breechface prevented it from completely seating. Took a good bit of trial and error to get the epoxy melted and the liner removed... a propane weedburner from Harbor Freight finally did the trick. A couple days later had the liner glued back in place, this time flush up against the breechface.

Drilled and tapped a 5/16" hole to within 1/8" of being completely through the new liner. Drilled a common hardware store variety lengthwize to accept 1/8" fuse.... note to self, this significantly weakens the bolt. Lathered it up with Lok-Tite blue and managed to break off the head of the bolt when it bottomed out in the threaded hole. No big thing, it broke off fairly flush with the surface of the barrel... I can live with that... was going to cut off the excess anyway.

Now all that was left was to complete drilling the fuse hole through the remainder of the new liner. All was going well until the bit seized up and broke off.... naturally there wasn't enough extending from the vent liner to get ahold of with a pair of pliers or the like. So........ off to the local hardware store for some diamond faced Dremel tool bits. The current plan is to fire up the acetylene torch and heat up the broken cobalt drill bit enough to destroy it's hardness. Then should be able to Dremel the remains enough to get an ez-out inserted and remove the entire liner.

Think it will work?

Might even redrill and tap up to 3/8" this time and use threaded brass rod for the vent liner.
 

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E.D.

Time out!!!!

After you get the vent out, park the cannon.

Then go get your Switlik out and carefully read the section on vents. (Page 80 in my copy)

Make a proper vent piece out stainless steel as Switlik recommends. Forget the loctite you want anti sieze grease.
 

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Red or blue Loctite?

Broken bolts are my bread and butter, I have to get a LOT of them out in my line of work.

The way I get out bolts that are broken off flush is to weld a nut to them. Don't try to weld the nut directly to the bolt (vent liner), you want to build up a small bead on the end of the bolt, then sit the nut down over the bead and fill the nut with weld. You want to get the nut as hot as you can without it melting. The heat from the nut will expand the bolt, breaking it loose. When it's cold it should screw right out.

I do this a LOT.

This works with blue Loctite, but if it's red it might be a problem.
 

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Terry C. That is an awesome trick !
I filed it in my mind.

Make a proper vent piece out stainless steel as Switlik recommends. Forget the loctite you want anti sieze grease.
I am going to remember this one too. Double D.., This is for cleaning purposes and watering down black powder in the event one may need too?

There is always much to learn here.
 

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Discussion Starter · #5 ·
Hi Terry.... the nut idea sounds great but it might be a bit late to give that a try. The broken vent liner (a common hardware store variety 5/16" x 18 bolt) is not flush with the barrel surface... probably recessed close to 1/4" It was drilled 5/32" lengthwise before screwing it into the barrel. The hole that it was screwed into does not extend completely into the bore, rather it is about 1/8" short of breaking through. The bolt was coated with a moderate amount of BLUE Loc-tite. When it bottomed out in the hole it just twisted right off. That I could live with.... the trouble came when I tried to complete the 5/32" hole through the remaining 1/8" of liner. The cobalt bit siezed up and broke right off leaving nothing to grab ahold of. In retrospect, should have used a 1/8" drill and then reamed to 5/32". If I can Dremel out enough of a hole to get an ez-out to grab then hopefully the liner should back out. We are talking a liner that is close to 1 3/4" long. Sure did mess up this time.
 

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We've removed broken drills from hardened dies with a magnetic mount drill using carbide end mills. Tears up an end mill or two but they can be chipped out that way.

Again, you've got a lot of choices.

This WILL BE a good experience in retrospect.
 

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Discussion Starter · #7 ·
Certainly stretching the learning curve a bit though.
 

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Tropico said:
Double D.., This is for cleaning purposes and watering down black powder in the event one may need too?
Yes that is correct.

For cleaning and watering down black powder. As well as having away to repair the vent from the effects of erosion and proividng a solid vent to eliminate fouling getting between liner and barrel.

Anti sieze grease not loctite.
 

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maybe time to pay someone with an EDM machine before it gets worse?

Stainless Steel or copper bolt next time.

Anti-Seize instead of Locktite for sure.

I'm sort of a hacker with drills, but I found that HSS seems to be less likely to break than Cobalt.
 

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Discussion Starter · #10 ·
Yes, I can definitely see the logic in finding a shop with an EDM machine. Make a hole large enough to use an ez-out and that should pretty much do the trick. Next vent liner will definitely be stainless.... and probably 3/8" instead of 5/16". Should be pretty quiet at work tomorrow so will have time to call around.
 

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Discussion Starter · #12 ·
Thanks for the info Double D... I do appreciate it.
 

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I think you'll find that an ez-out of a size to get into your small bolt won't do the job in this case - You've seized the bolt into either the bottom of the hole or (more than likely) into the tapered end of the tapped threads with enough force to break the head off. An ez-out (They would be more correctly named "maybe-outs") will probably end up expanding the bolt into the tapped hole before enough force can be applied to turn the bolt since so much force was applied to install it.

Also, you've got a bit of a sticky wicket in this case since you now have a hardened drill bit that's probably not jammed tightly into the hole - It can move around in there and resist cutting even with a carbide drill or end mill. It might chew up expensive carbide tools without doing too much cutting in the process.

As far as Loctite goes, 400 degrees of heat will melt any of their red, blue or green threadlockers. I don't think heat will help you much in this case though.

Your best bet is to find an automotive machine shop that has a simple "bolt burner" EDM machine that uses a copper tube as the electrode. They will more than likely charge you less than any machine shop that might have to set up the barrel on a die-sinker EDM with a graphite electrode.
 

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Did by any chance this drill break off just as it broke through like they typically do? If so just drive it through a little bit and using a long rod break it off inside a little at a time until its gone. Then heat and extract or drill it out.
 

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Discussion Starter · #15 ·
Somehow the simplest things continue to elude me. You're right Double D.... hadn't thought of that. Will have to get out a punch when I get home and give it a try. I really doubt that it could make the situation any worse and just might turn out to be the solution I need.
 

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EoD,
What is your link to McMaster-Carr for? The link does not work for me, even when cut-and-pasted.
 

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Take a nut and grind the edge at an angle until it goes in the hole and touches the bolt piece. Weld this to the bolt and back it out. Have done this to my WW2 Willys Jeep block 3 times to get the studs that were broken off out.
 

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Strange me neither, O’well It was some predrilled vent cap screws in stainless. At least a pilot hole to get started in the right size for a fuse hole.
 
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