Step by step fabricating a .30 cal miniature black powder cannon *Now with video*

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Hello!

A few days ago I began researching black powder cannons and became very interested in how the worked, were built and functioned. I was surprised to find that it is completely legal to build them and fire them in most areas.

While many videos and groups i found were for cannon enthusiasts firing massive cannons, bowling balls, and golf balls, I wanted to start MUCH smaller.

I found a number of articles that laid out how to safely fabricate these and made mine WAY oversized to compensate for my irrational fear of creating a massive baby-killing bomb of some sort.

Without further ado, here is a 19 picture series of my fabrication process.

A little about me: I am a knifemaker so have all sorts of metalworking goodies including a 1944 bridgeport mill, a KMG 2X72" belt grinder from Beaumont metalworks and a crapload of other metalworking and finishing tools as well as almost 10 years of experience fabricating knives. This cannon was the easiest thing I've made in a long time and I'd say it took me a total of maybe 2 hours, including the finish work.

I'll do this in a series of a few posts.

I began with a pretty solid hunk of steel. Its nothing special as I've found mild steel is more than enough for these based on research. I first cleaned up the block on my Bridgeport mill for squareness and sprayed it with layout fluid. The block began with dimensions around 2.75"X1.5"X1.25":
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Next I scribed some lines to keep things relatively straight. I didn't go anal retentive on precision here as this is not as intricate as my folding knives but I am a bit OCD about certain things so its still pretty dead on. I'll be shooting 5/16" ball bearing out of this (slingshot ammo) so I first drilled a starter hole a bit smaller.

Here it is in the vice with the smaller drill bit:
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And here's the initial hole. I drilled this one with a #16 drill bit. I did this for a reason I'll explain in a bit:
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The bore on this is somewhere around 2". I am going to use 2mm cannon/fireworks fuse so I drilled with a 5/64" bit as 2mm fuse is around .0760 and you want almost no clearance to ensure you're not losing excess pressure out the fuse hole on ignition. Here it is all lined up. What you dont see is i have the block angled about 5-10 degrees so that the fuse burns at an angle towards the front of the bore. I let the fuse hole intersect the bore a few mm from the rear of the chamber:
4.jpg


The reason I started with a #16 bit is that it leaves a hole EXACTLY big enough for a .177 BB. This allowed me to test fire the cannon. Holy crap, pretty loud for even a little cannon. It blew a nice clean hole through a tin can, made me jump and started the dogs barking. Good sign.

Into my shop I went and bored the hole out to 5/16. A 5/16 ball bearing is exactly .0312 while a 5/16 drill bit is .03125 although without going crazy with tolerances and care it usually leaves a hole a smidge bigger which is what you want. Here's the full 5/16 bore done:
5.jpg


Next post I get into a few finish details that I chose to do.
 
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Next I headed over to my little beast of a grinder. It runs a 2"x72" belt off a 2HP motor and hogs steel as well as flesh pretty easily. I've lost more skin to this badboy over the years than I care to mention. I've paid it in blood and its paid me back.

I set the platen to somewhere around 45 degrees although i honestly just eyeballed everything from here out.

Initial bevels ground:
6.jpg


Once the bevels were in, i thought to myself "heck i may as well put some sights on this. Obviously i really wont be aiming a smoothbore 2" barrel at much but hey, why not? Good excuse to fire up the mill and make some chips. I viced it up thew in a four flute 1/2" endmill:
7.jpg


Here it is after the first pass...mild steel is SO soft compared to the stuff I usually mill.
8.jpg


Here it is after a second pass, leaving a ridge in the back for the sight notch. Looking good as far as I was concerned. I left a nice rough finish as I knew i'd be cleaning it up on the grinder:
9.jpg


I put on a 220 belt and did some initial beveling of sharp edges, deburring etc. I also counterbored the bore. First time Ive actually used a counterbore on a bore. Ironic! As you can see, the steel heated a lot during grinding causing some surface rust in the bore. No biggie as I planned to do a final reaming later.
10.jpg


The only part that couldn't be finished by machine was the space between the sights. Ugh...I'm used to hand sanding so out came the block and paper. I've developed a skill at mundane tasks knifemaking so this was easy:
11.jpg


Next up: Finishing it off
 
Back to the mill to put in the rear notch. 1 minute later. How do people get by without a mill? Ugh i remember the days of hand tools only before I sold enough knives to begin buying tools. Those days sucked:
12.jpg


Being an egomaniac, I had to put my name on this thing. I etch my name by electricity. The etcher uses basically a stencil much like a silkscreen stencil, an electrolyte solution and AC/DC current. Here's the stencil in place:
13.jpg


And etched. I didnt go too deep as it eats up the stencils and I save that for stuff I sell. You'd still need to grind this off to remove it. Now when this thing gets registered as a WMD, they'll know who made it:
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A few final shots on the vice. Back:
15.jpg


Front:
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Bore:
17.jpg
 
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And finally, a few shots in my hand. What a cool little project. I had fun, learned a bit and have a new toy to play with.

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I'll probably make a little box for it as well as some kind of stand with elevation control. I see a few of these as gifts for friends in my future.

Disclaimer: Don't do this. If you do something like this and kill yourself, its not my fault or problem. Do your research, be safe and be conservative. Also, no...i wont make one of these for anyone else. There's probably some fine line between a BP cannon and a pipe bomb and I'm not sure where that line is. I'm sure that line is somewhere around an oversized projectile, an overstuffed barrel full of powder and a much smaller chunk of steel. I'm no cannon expert so I'll leave that to someone else.

As soon as I get a chance to take a video of it firing, I'll post it up here! Until then here is the test video from the .177 bore. The .177 sounded like a loud firecracker or a bit more. I assume the .30 bore will be twice as loud/powerful.


Thanks for looking!
 
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Okay so I fired this little badboy after work today. WOW. Much, much louder than I anticipated. I might need to dial the load down if I want to use this in my yard without cops being called. I cant say for sure just how loud it was but it echoed throughout the neighborhood, put my dog into full shaking mode and made a girl in a yard somewhere in my neighborhood scream. The ball bearing embedded itself about 1/4" into a 2X4 and the blast drove the 1.25 pound hunk of steel a few inches back.

This thing is not a toy by any means. Can't wait to go camping and blow apart various things with it.

Here is a video. If you turn the sound up you can actually hear a little girl scream in the background...nice!

 
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In MA you'd be in violation of 527 CMR 22.04.1

Can you bring that to the upcoming NES shoot @ Monadnock? We have a shortage of cannons at the shoots.
 
Step by step fabricating a .30 cal miniature black powder cannon *Now with vide

Can you bring that to the upcoming NES shoot @ Monadnock? We have a shortage of cannons at the shoots.

Sure!

I also have some 2" round cold rolled stock...may bore out a .50 cal salute cannon. I hear they can get pretty crazy loud once you go up to .50 or larger bore...but that's getting into powder charges that unnecessarily scare me. I'm sure 2" stock is still way over engineered to be any danger based on others I've seen but I'm no expert so I'd rather be safe.

I do now have a desire to make a huge boom...I'd love to get one of the professionally made golf ball mortars....

For the prices of the nice ones I'd just spend a bit more and get the lathe I've been eyeballing then make it myself...these are just bored holes we are talking about.
 
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Sure!

I also have some 2" round cold rolled stock...may bore out a .50 cal salute cannon. I hear they can get pretty crazy loud once you go up to .50 or larger bore...but that's getting into powder charges that unnecessarily scare me. I'm sure 2" stock is still way over engineered to be any danger based on others I've seen but I'm no expert so I'd rather be safe.

I do now have a desire to make a huge boom...I'd love to get one of the professionally made golf ball mortars....

For the prices of the nice ones I'd just spend a bit more and get the lathe I've been eyeballing then make it myself...these are just bored holes we are talking about.

Sounds like a fun project. I can bore the holes :) if your interested shoot me a PM. I just made a KMG grinder myself :)
 
So GOEX FFFg? or 4f?

I am using FFFg with great results. I am using just a small piece of paper for wadding, lightly packed with a wood dowel. With about as much powder as a 5/16 ball bearing it produces a nice loud report but not so loud that someone thinks I am shooing my 9mm in the yard like in the video I posted. I'm also going to try launching some firecrackers from this. I think if I put one in fuse-down it would ignite the fuse and launch it into the air nicely.
 
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