Oops.... how to remove a glued in liner?

[Evil Dog]

Hey guys... I messed up and could use some help on this one.  Have a Hern half scale Napoleon, 2 1/4" bore.  Decided that I would be much happier if it was sleeved down to golfbore bore.  So, had a sleeve turned that was just a few thousands under the existing Hern bore size.  Was a sliding fit and pretty much flush with the existing muzzle when put in place.  So far, so good.  Lathered it up with epoxy cement and slid it down the bore... stood the barrel on end to let the weight of the barrel keep it in place while the epoxy cured.  When I looked at it this morning I found close to 5/16" of the liner extending beyond the muzzle... not a good feeling.  The new sleeve has a very substantial breechplug press fit and then welded in place.  My guess is that there is now a 5/16" space between the end of the sleeve and the breechface of the original bore.  Conventional wisdom would have that heating the barrel should cause the epoxy to release.  So, hung the barrel from that round thing on the breech end and used up what little acetylene I had left, then switched to a large MAPP burning torch.  Not sure just how hot I managed to get the barrel but it could still be turned with a gloved hand from the round thing on the breech end.  Welding supply won't be open until tomorrow, suppose I could get a couple more cylinders of MAPP too.  Not really enough of the liner extending from the barrel to heat and put a pipe wrench on.... would rather not do that anyway.  If 5/16" space between sleeve and breech is safe then could just cut off the extending sleeve and face it smooth with the muzzle.... would really rather than the sleeve ALL the way into the existing bore though.

Any suggestions?

[cannonmn]

If you want lots and lots of heat, and you will need it to get the whole thing hot enough, get at least two of the $19.95 (or half that on sale) propane weed-burner wands from Harbor Freight.  Get two of the housetrailer-type propane tanks and connect one to each burner.  They will heat the barrel red if you want.  These burners put out a lot of flame, like a 3-foot blue flame about 3" diameter at the source, so you need to do it away from any combustibles, and have the cannon rigged up so you can put tension and torque on the sleeve as soon as it gets hot.  That means mounting it securely somehow, probably horizontal so you can work on the liner.  You may want to have some kind of gear pulling arrangement or screw jack arranged to pull the liner when all is hot enough.  You could call the epoxy's maker to see how they recommend getting it out.  They may know of a "release agent" other than heat, but can tell you what temperature the stuff melts at.

Maybe if you suspend the whole cannon by the liner, cannon pointing up, gravity will pull the cannon off as soon as it is hot enough.

If you decide not to remove liner, you could drill a hole and fill the space behind the liner with molten zinc, or some other strong stuff that won't compress, then tap the hole and run a bolt down it to close it, then saw the bolt off.

[Terry C.]

If it's a viable option, I like cannonmn's idea of trying to fill in the space rather than removing the liner.

Is this a cast barrel with a liner already in place?

What you have is a bad situation. If this were to to come to our shop, I would tell the owner that he can either have the barrel or the liner back intact, but not both. The method safest for the barrel (and 2¼" liner if it has one) would be the one most destructive to the GB liner.

[Victor3]

I would go the 'drill & fill' route. Devcon plastic steel will do a good job of it.

http://www.devcon.com/devconcatsolution.cfm?catid=34

[Cat Whisperer]

What you do is of course up to you.

I can envision hanging the tube from the cascabell (little bell - the round knob on the breech end) as you have.

Make a device from three wedges - the inner one has the big end on top the two outside wedges big end on the bottom.  The inner wedge has a threaded shaft from the small end to suspend a large weight.  All three wedges go into the bore, the weight pulling down on the inner wedge - the other two holding the sides of the inside of the tube.  (There are other arrangements that will also work as well.)

Then heat it up from the outside - non-destructive disassembly.

[Double D]

To melt that liner out you are going need to get the all  epoxy 100% melted all at the same time and keep it there untll the liner i s out.  But if you get it too hot then epoxy material will burn and turn into a hardened mess.  Don't ask!!!

Agree with the drill and fill devcon steel method

[Evil Dog]

Drill and fill may turn out to be the better option.  Got to thinking though that using the hang vertically and heat method, while the liner slipped in real easily with the epoxy acting as a lube, it will probably come out a heck of a lot easier if there is a vent hole drilled into that dead space between the end of the liner and the original breechface.... breaking any vacuum being created by the liner trying to come out.  Then should the liner still not come out drill and fill becomes the most viable option that vent hole could come in to real good use.  I like the idea of the weed burner for putting out some serious heat.

[Double D]

It's not an either or proposition.  If you start heating you must continue until you get the liner out.  If you melt the epoxy on one spot, burn it in another and don't melt it in a third you have compromised the integrity of the epoxy. 

If you want to melt the epoxy you need some way to uniformly heat the entire tube all at once and to the depth of the epoxy at teh temperature needed to melt the epoxy.

Leave well enough alone and drill a hole from the bottom and fill with devcon steel like Victor suggested.

[Victor3]

 If filling the space with epoxy, I would drill three holes from the rear into the void, 60 degrees apart and near the outside diameter of the void. That way you can inject the epoxy into one and see it ooze out of the others. This will give you a good indication that the entire void is filled.

 For future reference, it's a good idea to drill a hole at the base of the bore before using epoxy to secure a liner. If not, the liner (As you have found) is going to act as a piston and push out some unless it's clamped into position until it cures. By drilling a hole, you also help to ensure that there will be no air pocket left at the breech end since you have provided a way for it to escape.

[rusty barrels]

I don't know how you can find out but, are you sure you now have a void behind the breach? Some epoxies expand when they dry.

[Rickk]

Here is a thought...

If you heat the barrel and liner up above the softening point of the epoxy, and then pour in an isopropyl alcohol/dry ice slurry, the liner will contract and pull loose the epoxy bond. Then you will need to pull like hell before the barrel itself begins to shrink back down or the epoxy starts to solidify substantially. 

Maybe weld a ring to the front of the liner so that you have something to grab. Secure the barrel to something via the trunnions and pull the liner out while the epoxy is soft with a come-along or an engine puller hoist.

[petersen_arms]

I think it's going to be very difficult to get it out without machining it out. If the bore end of the sleeve isn't to mucked-up from pipe wrenches, vise grips and whatever else will clasp it, maybe you could beat it back into place. I'm thinking a good chunk of wood with a clearance hole for the cascabell, another for the bore end and a big hammer and a bigger friend. It sounds like you can definitely heat it until it softens and I think you can apply alot more force pushing it down than pulling it out. You don't need much adhesion to keep it in the barrel, so if only a quarter of the glue is still bonding I bet you will be alright. Good luck and keep us posted!

[cannonmn]

People have removed stuck shells from muzzle-loading cannons by threading a zerk into the vent, and pumping grease in from an overhead, powered service-station grease gun.  If the greasegun put out enough pressure, you could drill a hole into the cavity and put a zerk in it. 

I don't think this would work in your case, unless the epoxy was weakened a lot first. 

You can take the operating pressure of the greasegun, and multiply it by the area in square inches of the rear end of the barrel.  This gives you the total force that will be exerted on the barrel to move it forward (example:  1000 psi greasegun x 2 square inches area=2000 lbs. axial force produced to shear the epoxy.  If the epoxy is rated at 1500 psi in shear, you can figure the total area of contact of barrel with liner, in square inches, and multiply by 1500, and you will have total force required to shear the epoxy in pounds.  I don't think any grease gun would do it.

[Evil Dog]

But if it did work, I'd have a bore that is practically guaranteed NEVER to rust.

[Double D]

John, the grease gun idea is a gut buster...we now know its not needed now the liner is out...I had the visual of the grease gun pressure going up and up and up and suddenly the liner flying out across the room and sticking in the wall. That is followed by this 10 lb ball of grease that hits the wall and explodes like a giant cow pie....Will glad you got the liner out.  But seeing the grease gun on video like I visualized sure would have been funny.

[Evil Dog]

Actually I have seen a grease gun used to unload a muzzleloading rifle where the shooter forgot to put in powder before the patched ball.  The percussion nipple was 1/4x28 thread to exchanging it for a zirc fitting was no problem.  A bit of pumping with a handheld grease gun and the ball came out safely out the muzzle.  Think that he used a hair dryer trying to melt most of the grease out after that... quite a sight to behold.

[Terry C.]

I've used the grease gun method to remove pressed-in pins and shafts from blind holes. Some if these required tons of pressure to install.

I don't know if this would have broken the epoxy bond without heat, but it's not as far-fetched as it might sound.

But it can also be dangerous. Put in enough pressure, and something WILL give. I've shattered some pretty heavy housings when the shaft refused to move.


Oh yeah, it IS messy. The part about flying gobs of grease is dead-on.


BTW (and slightly OT): We have some high-pressure grease guns that can exert 10,000 psi. These are hand operated, none of our pneumatic guns will go higher than 5,000. The track adjusters on most heavy tracked equipment use grease cylinders (my GB mortar is made from a ram from one of these adjusters), and sometimes they get frozen into position and can't be broken loose with a pneumatic or standard hand grease gun.

The procedure is to pump it full first and then switch to the HP gun. Because they move so little grease on each stroke, it takes a LOT of pumps to move a significant amount of grease.