Unspiking a cannon

[Robin Hewitt]

A pair of Falkirk 6 pounders c1800 with original carriages used by the Reed shipping line plying the South China Seas out of Cardiff.

Spiked c1914 when it became too dangerous and the cannon were moved to a tourist attraction schooner parked at Newquay.

It looks like the touch holes were plugged from the inside and then a steel cup was driven in to the bottom of the bore so you can't knock it out. A professional spiking, they knew what they were doing.

I sparked out one touch hole to bore depth, tried injecting rust remover but it wouldn't go in. Tried injecting 90 bar hydraulic oil and it laughed at me. Even tried a a little powder but it was not impressed.

I have a length of 1" studding which could probably pull it, but how to attach it to the spike? I don't want to make things worse so glue seems like a really bad idea. An expanding plug maybe, but I don't want to clinch it even tighter.

Bores are around 3.6" diameter by 43" deep. The cannon weigh close to half a ton each which doesn't help.

Help

Edit: Best to mention this is totally legal, I have shotgun/firearm/gunpowder permits. The cannon are pre-1939 and classed as curiosity or ornament.

[Stepper Monkey]

That is awesome! I don't know if I can help, but here are a couple of thoughts;

Can you describe the plug a little better? I have having a hard time visualizing exactly what it is in there. It isn't quite the same thing, but when salvaging historic engine blocks to run again after sometimes 50 years in water, you have to get out the internals without srewing up the block. There are a number of almost counter-intuitive methods that might help if I knew what you were up against better.

Also, this is a longshot, but are there significant differences in metallurgy that can be used to advantage? Sometimes a small battery and some saltwater can do more than any machining bit. Weak acids too. they all take time but there are ways to leverage a metals difference.

[Robin Hewitt]

Hi SM

The cannon is cast iron, I think the cup is wrought iron because the rust off it is flaky.

I have tried to get pictures but it's not easy from 43" away.

I electrolysed out the rust and cleared what was left with organic acid. You can see the step in this pic, the mirror is refecting where the touch hole should be.

The bottom looks smooth almost like lead or zinc and there seems to be a small lip but I think that's just an illusion. The bottom is hard as nails, I hit it with a steel spike and a sledge hammer, didn't even mark it.

When I ran a 4" rotary wire brush down it, I could feel the last few inches were much tighter, it's a cylindrical cup or a cylinder over something.

Perhaps I should see if there's any electrical resistance between cup and cannon, I think it's just rusted in solid. It really needs removing so I can stabalise it.

best regards

Robin

[jphagen]

If there is a cavity behind the plug. You could drill and tap a port to it, then use a hydrolic pump to push the plug out.

[Robin Hewitt]

If there is a cavity behind the plug. You could drill and tap a port to it, then use a hydrolic pump to push the plug out.

Tried that, 90 bar oil wouldn't penetrate, thought about 300 bar air but then thought it might come out too quick to catch easily

[Kevin Taylor]

Can you drill through it with carbide and leave the plug in there would just be a liner in the end if you could get through it Good luck Kevin

[Robin Hewitt]

I was rather hoping to pull it like a rotten tooth so I can kill the rust behind.

The best solution I can think of is to groove it and use a collet, that way there is no expanding force. I have CNC, I can make the tools, but it's a lot of work.

The easy way is to epoxy a handle on to it, but what if it didn't come out <angst>

If there is no simple answer that's okay, I'll start on the collet

[JerryFlyGuy]

The shear load holding that plug in there [the rust] would well exceed the strength of the epoxy [ I'm pretty sure] your best be it to groove it as you've stated and pull it out in chunks, even then it will be a challange.

What about just tipping it up on end [barrel up] and putting some type of acid into the cup, and letting it eat its way through to the bore, timing it all would be the challenge. To much and you'd etch the bore, too little and it won't go through far enough..

Not much of a help..

Jerry

[tool_man]

I would like to offer the best advice you will receive.You need to talk to Paul Barnett at South Bend Replicas in South Bend Indiana.His phone # is,(574)289-4500.He is probably the leading authority on antique ordinance in the U.S.I know he has removed cannon balls from barrels,repaired broken cascabells,and restored many original barrels.If anyone can help you with this problem...he can.
By the .....nice barrel.

[lerman]

First you need to get a good look at it. Find someone with a borescope that can reach to that depth. Your local scuba tank inspection place might have one.

If not, try your local gastro enterologist. A colonoscope should be good for something useful. :-)

Perhaps a small diameter digital camera on a stick would do the job. Or a cell phone camera.

Ken

[bcromwell]

How about electrolysis? Get your self:
a big trash can/Kiddy Pool etc,
baking powder/washing soda
4-5 pieces of rebar
car battery charger (12 amp version works great)
and some wire, leave it a few days to a week and all of the rust will be gone, if the stake is made out of aluminum it will be gone too (I believe)..

http://www3.telus.net/public/aschoep...lyticrust.html

[Tate]

I agree that electrolysis or acid would be your best bet. I remember using Sam's Choice cola to free pistons that were in a motorcycle block for 15 years.