Logic and homemade cannons

[nightwolf1974]

i just read all the posted articles about cannon disasters, it's a good but sad read.

I have faith in my cannon designs, but still treat them with respect. I use high grade, thick walled bushing material for barrels and pin stock for plugs that I beat in and have my father who's been welding for 50+ years weld the plug in.

I proof the barrels before they go onto the carriage for wether they are just for making noise or shooting a projectile out of it. I don't load them to maximum potential. And always have them 100' from anyone. I use slow fuse, and run like crazy after lighting it.

a neighbor of mine uses a 1/2 pound of powder at a time in a cannon they built with some not so thick walls....I stay clear of them. IF more people used their heads and some logic when building cannons, there would less accidents for the media to play up and give our hobbies tarnished reputations.

PLEASE BE SAFE, AND ENCOURAGE OTHERS TO DO SO TOO.

 

[carbineone]

I do not know how confident you could be of a design if you have to, run away, from it like crazy

You should not run away. Walking away in a safe manner is much safer.

How do you "proof" your barrels? It is not a good idea to put a large charge and fire it. It just stresses the metal in my opinion and could lead to a potential problem down the road, more than tell you anything about current strength. It should be safely built to standards, properly loaded, then there is no need to run from it.

A Breech plug should not be "beat" in.

Proper way is threaded, or the barrel heated and shrunk fit to the plug. Pinned is also a good assurance if you do use a breech plug. You should even avoid a plug at all if possible. Proper way is to bore solid stock eliminating the plug. But it can be plugged, if done safely.

I am confident in my Cannons I build. I stand within several feet when they are fired. I never have to run away. Most of mine are fired with a Cannon Lock and Lanyard. I do have a few tiny ones where this is is not possible because of their light weight. But I still do not have to light the fuse and run 100 feet away. If I did, I would rethink what I built.

I may somewhat harsh in my comments. Just trying to add some helpful info to encourage others to be safe.

 

[coloradoclyde]

And always have them 100' from anyone.

If the projectile is capable of travelling more than 100' so is shrapnel from a failure.

 

[zimmerstutzen]

Seen too much dangerous junk for cannons over the years. Got a few small cannons myself. I am very very cautious about barrel wall thickness, breech thickness etc. In my college days I did dumb stuff and survived without a criminal record. Some of the things we jury rigged/built etc were dangerous and today, would be highly illegal. A college acquaintance was burned when his "flame thrower" blew up. Not seriously, but enough to quash our reckless creative desires.

Even when firing my cannons, it is from a hill top far far from any spectators.

 

[Donny]

Count me among those who saw a homemade cannon accident. No one was injured, the breech blew & busted the box about 6' back. It was welded on. I was standing only about 8' from the damn thing. If the box hadn't stopped the metal ? ? The guy was an excellent welder and experienced cannoneer.

 

[zimmerstutzen]

Experienced cannoneer? Even more so now.
Hopefully for the better.

I don't like welds around gun barrels, especially welded breeches.

 

[Zonie]

IMO, the thing about welds is of course, they can look good but have almost no penetration.

In some cases, the metal around the weld can be compromised by the intense heat.
Not so oddly, this is called the heat effected zone.

Perhaps the biggest problem when welding a breech plug in is the weld is little more than a thin area of metal joining the barrel and the breech plug. One could almost say the area looks like a couple of thick pieces on each side of the weld joint, joined by a much thinner piece of sheet metal.

Thinking about this sheet metal thick weld zone one could correctly compare it with a punch and die with the breech plug acting as the punch.

I don't know how many of you have designed dies for punch presses but one of the first things you learn is it takes much less force to punch a hole thru a piece of stock than the tensile strength of the material would seem to require.

For instance, to punch a 2 inch diameter hole thru a 1/8 inch thick plate (or weld) requires about 40,000 pounds of force.

That seems like quite a bit and it is but when we are dealing with explosive forces which apply the force almost instantly the pressure needed is less.

For instance, in calculating the wall thickness of a cylinder to see if it will be safe when subjected to an internal pressure is pretty easy to calculate if the pressure. the diameters and the material strength is known.

The value you get seems reasonable until you look at the footnotes.

To be safe, the wall thickness should be increased by a factor of 4 if the pressure is applied in the form of an explosion.

That can change a rather thin amount of material for the answer to a very thick one in a hurry.

Anyway, I'll quit my rambling.

(As you can tell I don't recommend welding in breech plugs in any gun or cannon.)

 

[Obi-Wan Cannoli]

...the breech blew & busted the box about 6' back...The guy was an excellent welder and experienced cannoneer.

This would be the point where I would realize that cannon building was not my calling. :td:

 

[Donny]

Well it certainly was a learning experience
for me. :surrender:

 

[Obi-Wan Cannoli]

It wasn't directed towards you, it was for the guy who blew up the cannon he worked on.

 

[Donny]

Yes I know. I learned to stay away from things that go boom that I know nothing about, or the owner. :grin:

 

[zimmerstutzen]

About 15 yrs ago, near Gettysburg, PA at a 4th of July party a guy was firing a capped plumbing pipe on wheels. It exploded after about 10 shots and killed a bystander. The fellow was prosecuted for negligent homicide or a similar charge and ended up doing half of a five year sentence. His family broke up, a guest-relative was killed and it was tragic all the way round. I recently read of a cannon accident in Germany in which the leader of the cannon crew was killed by one of the pieces. In Germany, cannons must be proofed and checked at least every five years by a government lab. AND THERE WAS STILL A LETHAL ACCIDENT. The accident at FT McHenry showed insufficient "meat" in the breech area as the failure. I may get up close to a cannon to examine it. I don't ever get close when it is being fired. Even my own are fired with a long pull cord or long fuse. I measure myself to figure, breech thickness and barrel wall thickness. Would not trust firing anything without my own measurements first.

 

[matt denison]

Number 1 cannon safety rule in the Dixie catalogue:

NEVER shoot a cannon with a welded breech plug.

'nuff said.

 

[steam1993]

I have never built a cannon yet!. But if I do I will bore from solid, or use a screw breach(I am a trained machinist and welder). To weld in a breach you would have to grind or machine a good grove to get good depth of weld, but I still would not do it.

Also how are you going to put in a harden steel liner, if you want to live fire. I don't know how many of us can/want to shrink fit a liner in.

 

[robinghewitt]

I think shooting cannons is fun and I light mine with a hand held gas blow torch because it is fast and sure, much better than that smouldering rope nonsense.

Nobody in their right mind will say their cannon is not going to blow up because that is called "Tempting fate" and you have to touch wood and carry all kinds of lucky charms to undo the damage done by your fat mouth.

Just because idiots occasionally explode for no apparent reason does not mean sensible folk can't have some fun.

Touch wood :thumbsup:

 

[Poor Private]

On my 1" swivel gun I mounted a slap hammer. This uses a musket cap for firing. The good thing about it use activate the hammer with a string/rope which can be as long as you want it. The other 1" cannon that I have I use Cannon Fuse. I buy it by the 50' roll which means the length can be anything you want.

 

[zimmerstutzen]

no apparent reason is the realm of superstition and ignorance. There is always a reason, whether operator error, design error, manufacturing error, work hardening, material flaw, etc.

There may be situations in which we do not ever discern the reason, but there is a reason.

Lawyers have a doctrine known as Res Ipsa Loquitor. Basically means bad stuff doesn't happen without a reason. elevators don't fall unless there has been some error.

It may be an error that requires some special knowledge to figure out. My approach to cannoneering is leagues apart from some. Been told many times that I am overly cautious.

I was never hurt, but did some mighty dumb stuff in years past. (my first home made cannon blasted a blue crab all over a Delaware state police car. Long story,, My Uncle successfully bribed the officer with a few good cigars, so i was given leniency, only 10 years old, had to surrender my cherry bombs, wash the police car and write an apology. Times were different back in 1961)

 

[Col. Batguano]

That was before the sunset of the; "boys will be boys" statute.

 

[satx78247]

The early '60s WERE very different. = In my little East TX hometown a group of us built a 9 foot long, 6 inch diameter liquid-fuel rocket in Chemistry class & that "detonated" inside the HS, went through the roof of the school & ended up in a farmer's pasture about 3-4 miles out of town. - The farmer was NOT pleased as it scared his dairy cows nearly to death.

My dad was one of 18 parents who paid $$ to pay for fixing the school's roof.

In 2016, we likely would have been fined/jailed as "minors in need of supervision" or worse.

We also made a LOT of (REALLY BAD) "moonshine" in the schoolhouse too.
(The County Superintendent of Schools pretended that he didn't know about it, as his 15YO son was one of the "moonshiners".)

And then there was the catapult that we all built in "shop class" that threw five gallon-size FIREBALLS of Kerosene-soaked cotton waste -------.
(But that's a story for another time.)

yours, satx

 

[robinghewitt]

no apparent reason is the realm of superstition and ignorance.

I don't really believe this stuff but why take a risk?

Never had enough gun powder when I was a boy. Then around 1998 I realised I was grown up and trustworthy so if I still wanted gunpowder I only had to ask for an Explosive Certificate and buy as much as I liked.

Grown up, trustworthy? The fools :rotf: