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Discussion Starter · #1 ·
If I was going to make a cannon barrel, which metal would be best??
Average Mechanical Properties
Condition Tensile ksi Yield ksi Elong.in 2'' % Red. of Area Brinell Hardness
4140 Annealed* 80 60 25% — 163
4140 Vac. Deg. Q&T** 140 130 13% 40% 285/341

I was thinking of getting a 3 1/2'' O.D. with a 7/8" wall and a 1.75" bore but it comes in the 4140 Vac. Deg. Q&T. or i get a 3 7/4'' O.D. with a 3/4" wall and a 1.75" bore in the 4140 annealed. What would be the best??? Also does anyone have a info on doing the press fit, pinned and welded breech plug??
Thanks guys!
 

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Re: Golf Ball Cannon

The steel is fine.

The only safe cannon/mortar building standards that I am aware of come from the North South South skirmish Association. They recommend the wall over the breech be one caliber thick. If you have a chamber that is on inch in diameter, the you wall should als be one inch in diameter or totla diameter of 3 inched over the breech.

We have a link to N-SAA rules and regulations in the sticky at the top of the board called safe loads an cannon plan.

Breech plug construction is also discussed in the N0SAA rules. They recommend shrink fit and weld. Can't convince my self that pinning adds to strength. I my mind it weaken the barrel.

You will also find correct bore dimensions in our reference sticky for a golf ball.

Cat said:
A golf ball gun with proper windage would need a minimum bore of 1.723 inch.
The diameter of a golf ball is 1.68 inch. . (1.68/39)x40=1.723
http://www.learnaboutgolf.com/beginner/balltypes.html
 

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Re: Golf Ball Cannon

Both of those steels are plenty strong but absolute strength is not the only thing to consider when making the choice. All flavors of 4140 are not readily weldable and, for me at least, this would be a greater concern than material strength, as black powder pressures are not real high when using normal shot weights and powder charges.

Since welding is my choice for attaching trunnions (I normally drill from solid or thread a breech plug), a material that welds easily is more important than one of extreme strength. That is why I make barrels from either 1018 or 1020. Both are adequately strong and easily weldable.
 

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Re: Golf Ball Cannon

There are formulas available (probably online somewhere) for shrink-fitting of steel assemblies.

For your size of tubing, I'd make a 3" long plug, .003-.004" larger than the ID you bore the end of the tube (you do need to bore it to make sure it's round). Heat the tube to ~500-600 degrees, drop the plug in and let the tube cool.

On the weld, if you were to put a 1/4" x 45 degree chamfer on the ID of the tube and OD of the plug and fill it, that would be more than enough if you have a solid shrink-fit.

Unless you're already familiar with the procedures required to weld 4140 successfully, I'd take GGaskill's advice and go with a more forgiving material.
 

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Re: Golf Ball Cannon

Agree with mild steels being OK (1018-1020- et al.) One of the first one's built and posted here used 1024 to line a bronze or brass barrel.

They are excellent for taking the REPEATED stresses of firing. I look at the Charpy notch test as being a good indicator of being able to handle resistance to stress cracks MUCH more than tensile and ultimate strengths. (Because strength-hardness-brittleness go together.) Brittleness makes the difference between a cannon and a bomb.

4130/4140 steels are close. Both should be preheated prior to welding. (Get a CERTIFIED welder - thay should know what they're doing - it is your life.) 4130 is more weldable than 4140 or 4150.

Good design (adequate wall thicknesses and a rounded form of the inside transitions of surfaces (to reduce stress risers) ) and good mild steel are a quite reasonable way of building cannons. 4140 is today's standard for rifle barrels - but 1018 was used EXTENSIVELY.
 

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Re: Golf Ball Cannon

Pinning does not add enough strength to the design to use in some cases, depending on pin diameter, it could weaken the barrel. If you have access to a lathe, threading the breach plug then welding adds much more strength.
 

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Re: Golf Ball Cannon

Threading is OK, shrink fit is better as one looses much stength from the cutting into the metal by threading.
Trade-offs in everything.
 

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Discussion Starter · #8 ·
Re: Golf Ball Cannon

What I want to make would be a golf ball cannon about 20" OAL with a straight barrel(like a pipe). Would it be best to buy the hot rolled round 1018 or 1020(4") and bore a hole down the middle (1.723") and stop short and then use a smaller size to do my powder pocket. or use a 4" pipe with a 1.5" hole and bore it bigger and shrink fit and weld my plug?
Does anyone have any drawings of this type? and If i shrink fit the plug, does anyone have a drawing of the plug. I just need pics!! Alot of the threads I have been looking at talk about pics but i can't see them ???
Thanks Guys, I want to make this as a Christmas present for my brother!
 

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Re: Golf Ball Cannon

DO NOT use anything called "pipe" for a cannon tube. Pipe is designed for liquids, usually at low pressures as compared with black powder explosions. Thick wall tubing is not to be confused with pipe.
 

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Re: Golf Ball Cannon

I just need pics!! Alot of the threads I have been looking at talk about pics but i can't see them. ???

Lots of pictures get posted on various "free" hosting sites that do not retain the images forever. Consequently, older threads become filled with various kinds of not found icons or no images at all. Not much can be done about this other than for posters to use more permanent hosting sites or repost the images when they disappear.

Speaking of images, below is a drawing of the breechplug I made for a bore liner that converted a 2.25" bore to a golf ball bore.



It should also show a chamfer between the plug and tube where the weld is built up. The plug is about .003" larger than the space bored for it. In this case, I think it was just pressed in place rather than heating the tube, but I really don't remember those details. The internal curve (I used the 3/8 radius) was cut by step turning and smoothing the steps with files and abrasive paper. By recessing the chamber from the edge, the explosion tends to expand the lip of the breech plug against the tube which is trying to shrink against the oversize plug and prevent fouling from getting between the two pieces.
 

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Re: Golf Ball Cannon

405winchester said:
What I want to make would be a golf ball cannon about 20" OAL with a straight barrel
If you just wanted to buy something like this, you might look at what Dom Carpenter (one of the board sponsors here) has to offer. I'm sure if you talked to him, he could make you something just like you're describing for a reasonable price.

Look at the 2nd cannon down on this page...

http://blackpowder-cannons.com/products.htm
 

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Discussion Starter · #15 ·
Re: Golf Ball Cannon

Victor3 said:
405winchester said:
What I want to make would be a golf ball cannon about 20" OAL with a straight barrel
If you just wanted to buy something like this, you might look at what Dom Carpenter (one of the board sponsors here) has to offer. I'm sure if you talked to him, he could make you something just like you're describing for a reasonable price.

Look at the 2nd cannon down on this page...

http://blackpowder-cannons.com/products.htm
If you look at the link, it does not look like that cannon is over 5"od?
What am I missing?
 

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Re: Golf Ball Cannon

In that example, yes. But you don't have to have a chamber only 1" diameter unless you were using 3" diameter material.
 

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Re: Golf Ball Cannon

405winchester said:
Got a price on 4.5" od Hot rolled seamless with a 1.5"id ( bore to size) for $58.00 a foot. Does that sound like a good price?? You guys have been great with all my questions!!!
Sounds kinda high to me, but I haven't bought any tube in a while. Since you can bore the ID, solid could most likely be had cheaper than tube.

Making your own barrel brings a lot of satisfaction; I've made a few. The reason I mentioned Dom is that he could probably make what you want for about the same price as you would pay for material, tools and supplies. He does custom work, so don't go only by what he has listed on his website.
 
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