Oxy/Acetylene Spud Cannon... labor day madness

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Owly055

Owly055

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I always tend to go to extremes............ Yesterday I built a spud cannon from a piece of 2" inside diameter 2.5" diameter seamless stainless steel tubing about 3' long. It mounts in a frame that rests on the ground with a single bolt to tighten it for elevation. A piece of 1/2" steel was welded on the bottom end for a cap, and a 1/2" bolt passes through the barrel about 10" from the base to act as a stop for the spuds as well as a pivot point for elevation. A home made wing nut tightens it.... a very large one. The base has a hole threaded for 14mm sparkplug thread, and a stove ignitor (110vac) is mounted to the frame with one lead grounded and the other attached to a spark plug wire. The business end of the barrel is ground to a sharp taper to cut the spuds to fit. The mounting on top of the frame is two slotted holes so you can lift the barrel out very easily.

Once the spud is set to full depth, I light the acetylene cutting torch and adjust the flame, then stick it in the spark plug hole for about 20 seconds, pull it out and quickly screw the spark plug in finger tight. I step outside and drop the barrel in the mount and tighten it up, adjust the elevation and windage, walk back a ways and plug the cord I have on the ignitor in. The concussion is pretty awesome. I'm firing across main street over a vacant lot out over a hay field toward the highway (a mile away). Nobody in town is home this weekend except myself, but I'm sure I'd draw a crowd if they were. This is a small Montana town and people shoot off the back porch, etc all the time...... a pretty laid back community.

The gun carriage doesn't flip over.... which was my first concern. I built it long enough that it will lift and drop, but not flip. The first few shots I was a bit scared of it.... wasn't sure weather it would flip or the barrel would flip over. It seems pretty safe. The only issue I have with it is that 2" is too large.... it requires some pretty fair size spuds.


How's that for some Labor day fun? I'm taking it over to a friend's house about 1/4 mile away this afternoon. He has a shooting range in his yard with a gravel pile back stop. Last time I was over there we were shooting APIs out of his 50 caliber Barret. (50 caliber machine gun rounds in a bolt action rifle).

H.W.
 
Glen and I did some precision artillery ;-) to the extent we could using a magnetic protractor level...... which of course didn't stick to the stainless steel barrel. Sighting in on a target 300 yards away, we fiddled with it until we were able to hit the target. The ballistic coefficient of a random hunk of potato is pretty unpredictible, but ultimately we were able to hit the target most of the time...... Made a bit of a mess and a good time was had by all. Lots of home brew and laughter and story telling. He had his sister and her husband over.... both around 70, and she kept asking "why would you do that?" Glen's wife understood perfectly....... But Glen and I have been doing crazy things together for 25 years. We've built some really interesting and complex pieces of machinery (agricultural). People hire us as a team...... He does the heavy lifting (big welding work), I do the control systems design and precision fabrication, electronics, hydraulics, penumatics, etc.... the detail work.

The outcome of our fun and games was that I went home and built a precision elevation system with a hand wheel, and an indexed scale. The barrel is elevated using a hand wheel on a threaded rod which pulls a pivoting support under the barrel back toward the pivot point of the barrel. The barrel rests on this support with a V shaped cradle. As the barrel goes up a pointer on the cradle tracks on a piece of tape measure glued to the barrel. This allows you to adjust elevation with some degree of precision.... It gives repeatability. My torches are all Harris automatic models.... a couple of 18-5s and a model 50 I use for welding. I parked the Victor 315 stuff years ago when I discovered the automatics. A single flip of a thumb wheel turns both oxygen and gas off, and back on. This is perfect for the cannon because I can set the flame, and flip the knob off, then stick it in the spark plug hole for X seconds. Each shot has almost exactly the same amount of fuel because you never adjust the mixture except the first time.

We looked at shooting energy drink cans....... but they are just a touch too large..... there's gotta be a product in an aluminum can that slides down the barrel just right..... Perhaps we'll find it one day. An aluminum can filled with water and taped shut would be perfect. I've joked about shooting full cans of Coors Lite.....but it might be a challenge finding a barrel that matched. The beauty of shooting a can of beer would be that even if it was a bit loose in the barrel, it would expand and make a seal from the pressure below. At long last a good use for BMC lite! ;-) Imagine a Coors Lite mortar.......

H.W.
 
How does lighting the torch create the fuel for ignition? I would think you would need raw, unfired fuel.
 
2grit said:
How does lighting the torch create the fuel for ignition? I would think you would need raw, unfired fuel.
Click to expand...

I light the torch just to adjust the mixture. My torch has a thumb wheel that shuts both oxy and acetylene off. I just stick the tip in the sparkplug hole and flip the thumb wheel on for about 10 seconds, and I have a perfect mixture. You can do the same thing with a normal torch by snuffing the flame out on your boot or a board, etc, then sticking the still flowing torch in the hole.

H.W.
 
This cannon or howitzer is a work in progress. At this point it's pretty crude. I haven't rounded off sharp corners or added any real refinement It will get wheels on the front next and a handle to pull it around by as well as trimming off sharp corners. I also intend to install a scale on the barrel so as you raise and lower, a pointer will tell you where you are.....Just a tape measure. It will also get paint.

Today was the first day of school, and all the parents drive right past my shop taking their kids to (rural elementary 2 room ) school...... I deliberately left it out in plain sight... It's pretty obvious that it's a cannon of some sort..... Should be the talk of the schoolyard today ;-)

https://www.dropbox.com/s/cvgouawtukf29he/SANY0788.JPG?dl=0

https://www.dropbox.com/s/cvgouawtukf29he/SANY0788.JPG?dl=0

https://www.dropbox.com/s/kfjlvll31ti4ww2/SANY0790.JPG?dl=0

https://www.dropbox.com/s/fm61lmn8iy4nq5l/SANY0791.JPG?dl=0

Note the hand wheel and link consisting of a threaded rod (5/8 nc thread). The link pivots at the strut end to compensate for angle change, and the threaded rod passes through a piece of square tubing on the rear. This square tube has two pieces of 1/2 inch pipe projecting into the ends so it can pivot on the pipe and stay in line. The hand wheel consists of a large nut with three Ford FE engine valve stems welded to it, extending outward and bent back on the ends you grab to spin it. It will free spin on the threaded rod if there is no weight. The threaded rod extends farther and farther back as you elevate the barrel which is a bit of a nuisance. I'm considering building it into a sort of half turnbuckle type system where the rod extends into a pipe between the hand wheel and the strut.

Where the barrel pivots, a 1/2" bolt passes through the barrel. Originally I used friction to hold the elevation, and you will see a wingnut made from a nut welded into a piece of pipe extending outward so the wings clear the channel iron frame. This frame is built almost entirely from very light weight trailerhouse channel....probably 14 or 16 gauge that was bent or rolled from flat. It's very flexible.

On the right, side in the rear photo, you can see the ignitor, which is that black thing. It was built from an electric ignitor for a gas cookstove. The entire thing is encased in body putty mounted to a steel plate, and had two heavy copper wires extending upward for points. I built it originally as a way for a lady friend who does silver work to easily light her torch. A micro switch was mounted to the bottom of the work bench, and she could hit it with her knee and it would start throwing spark. It worked great for me.......... but for some reason she just couldn't seem to light her torch from it no matter how many times I demoed it. I never could figure out why it worked instantly evey time for me, and she just couldn't do it.....I screwed one of the copper wires to the frame, and just drop the spark plug wire over the other. The micro switch....... or more accurately limit switch.... is the trigger.

The end of the barrel is ground to a cutting edge to slice sections of potato. It seems to work best just cross cutting the spud instead of trying to slip it in lenghtwise. I plan to put a little bit of taper inside the barrel also to give a nice tight fit.

Then there's paint.... I have black, red, antirust red, and yellow. I'm not sure what color to paint it.... I'm leaning toward the anti rust red. Painting frame only.

What's your vote on color?


H.W.
 
Chris_Primavera said:
I'm pretty sure that this qualifies as a "destructive device" to the BATFE so be careful
Click to expand...

"destructive devices" are pretty popular around here.......... and the BATF is not. How many people can shoot across main street without getting in trouble or step out in the middle of the street with a 12 gauge and the neighbor will step out and ask if you got 'em?

One of the funniest incidents here happened one night about 15 years ago. I had built a device to scare deer out of the garden. It consisted of a stack of two tires with a 5 gallon bucket set in them, a black plastic garbage bag, and a fan mounted to a hole in the bottom of the bucket so it hung down inside the tires. The fan was wired to a motion detector. When a deer walked into the garden area, the motion detector would turn the fan on, inflating the garbage bag which would stand there quivering. It was pretty effective.

One night my neighbor who no longer lives here was chasing a skunk with 12 gauge pump........... I wasn't home when this happened. The skunk ran toward my garden, with Rick chasing it. Everything was dark back there, as I have no outdoor lights..... I like it dark at night. Rick tripped the motion detector and the bag inflated, and he was so scared he shot it with a couple of rounds. A few days later, I discovered the shredded bag, but it wasn't for a month or so he confessed, and we had a good laugh.

Small town life among good old rednecks!

H.W.
 
Blowing things up is fun
Shooting things is fun
Shooting things that blow up is fun

Providing some government numbnutz irrefutable evidence that you did so?
 
gratus fermentatio said:
Cool build! Here's something I saw, thought you might be inspired:
http://store.xm42.com/XM42-Flamethrower-p/xm42.htm
Scroll down for a video.
Regards, GF.
Click to expand...

I can see where it would be great for ranchers burning ditch in the spring.........fire is NOT my thing. We have too many wildfires around here. Quite a few months of the year it's a tinder box.

That said, you would be impressed with my incenerator.... which I only burn if it's raining or there is snow on the ground. It has a tangental blower of my own design built using a VW fan on a 1 HP 3450 RPM motor....... Howls like a jet engine for some reason. It's 3' diameter and 6' tall with an open unscreened top. When I burn trash, fire stands about 10-16 feet above the top of the incenerator. My neighbors have burn barrels that smudge and smoke all day long when they burn, ultimately leaving a lump of charred paper, etc in the bottom. My burner runs for 30-45 minutes to burn 2-3 months trash..... the ash blows out the top and drifts into the hay field. It melts aluminum and glass, which runs through the grate and forms puddles below it. The sheriff's department insists that I call before lighting it because people have called it in a number of times thinking a house was on fire or something......... I suppose I should photograph my "inferno" and post it sometime...... I won't be burning again until November probably. I am extremely careful about fire........

H.W.
 
Finished the howitzer today.......It has wheels and a handle to tow it around by hand and help aim it. I rounded off and ground all the sharp corners, and I've painted the frame a maroon color.. it actually looks pretty good.


H.W.
 
Newsman said:
I wonder if you could do the same thing with carbide and water?
Click to expand...

It can be done.......BUT carbide cannons are rather dangerous if the barrel decides to explode on ya. On a side note, back in my wilder days, I used to mess around building spud cannons out of PVC pipe. The best one I ever built was a butane powered beast that would lob a potato about halfway across the 28 acre field behind my grandparent's house. I nicknamed it the 'Noisy Cricket' after the micro sized alien hand cannon from the movie 'Men In Black' because it packed one hell of a kick when firing. The Noisy Cricket was retired to the scrapheap of "Cool Things That Seemed Like A Good Idea At The Time." following an incident in which a UFP (unexpected flaming Potato) nearly set the field on fire. :D
 
Owly055 said:
I can see where it would be great for ranchers burning ditch in the spring.........fire is NOT my thing. We have too many wildfires around here. Quite a few months of the year it's a tinder box.

That said, you would be impressed with my incenerator.... which I only burn if it's raining or there is snow on the ground. It has a tangental blower of my own design built using a VW fan on a 1 HP 3450 RPM motor....... Howls like a jet engine for some reason. It's 3' diameter and 6' tall with an open unscreened top. When I burn trash, fire stands about 10-16 feet above the top of the incenerator. My neighbors have burn barrels that smudge and smoke all day long when they burn, ultimately leaving a lump of charred paper, etc in the bottom. My burner runs for 30-45 minutes to burn 2-3 months trash..... the ash blows out the top and drifts into the hay field. It melts aluminum and glass, which runs through the grate and forms puddles below it. The sheriff's department insists that I call before lighting it because people have called it in a number of times thinking a house was on fire or something......... I suppose I should video my "inferno" and post it sometime...... I won't be burning again until November probably. I am extremely careful about fire........

H.W.
Click to expand...
FTFY
YES you should!
 
I built the spud cannon for these two boys.... 6 and 9 years old........... A bit crazy?? But they both have guns and motorcycles, ride ATVs working cattle, help with artificial insemination and embryo transplant, drive pickups and tractors, and even know how to weld ( I taught them ).......... Not your typical city kids, they aren't afraid of mud, blood, manure, or much of anything. Ranch boys are raised differently from ordinary kids. How many 6 year olds own and shoot a 22 these days? The 9 year old just sold his 80CC dirt bike on Craig's List............with no help from his folks, took payment in two installments for $1300 cash, turned around and bought a 150 Honda for $1600 cash. making up the difference from his 4H money. Did you do stuff like that when you were nine??

I removed the videos I had posted here........... after writing this post I decided posting the videos was "indiscreet". I decided that having people who can easily be recognized by friends and family posted on a public forum was just plain stupid...... sorry ........ I'll shoot some stills of the gun next week in it's final form..... We shot off 20 pounds of spuds this evening.


H.W.
 
Black powder can be fun too. This is a beer can mortar that I built years ago. Lots of fun with the boy and always a crowd pleaser at the shooting range.



 
Man these bring me back to my potato cannon pops and I built back in middle school. Typical PVC with a BBQ igniter with the screw-cap to spray hairspray etc in. Lots of fun. The initial build just had the igniter wires dangling and I wound up having issues with that, and ended up wrapping them around set screws to fix that issue. Prior to that fix after a couple days of dicking around I couldn't get it to ignite. Unloaded the potato and then looked in to inspect why it didn't work. Lost a good portion of my eyebrows that day.
 
medicmike63 said:
Black powder can be fun too. This is a beer can mortar that I built years ago. Lots of fun with the boy and always a crowd pleaser at the shooting range.



Click to expand...

I hope the projectiles were full cans of Bud Lite ;-) I've threatened to build exactly what your pictures show, but never came up with the right barrel. Of course it would not have to be stainless steel.

Seriously though, beer cans should make ideal projectiles. The pressure on the bottom of the can should expand the walls creating a good seal. I think I would stay with the oxy acetylene or oxy propane....... because it's cheap and readily available.

Shooting cans of lite beer is an unmistakeable expression of your contempt for the product...... I might expand on that and shoot cans of the various brands of disgusting flavored and carbonated (usually caffinated) sugar water Americans seem addicted to. A Coke bomb or 7uP bomb .or Orange Crush bomb ............ might make a sticky mess.

These companies don't really care what we do with their product.... as long as we buy it, but they can't be insensitive to the statement of contempt that using their product for a projectile represents.......... Somehow I can't see an add proclaming "Coors Lite.... the beer most favored as a projectile by teens worldwide" (drop in Coke, Bud Lite, or whatever....)


H.W.
 
Owly055 said:
I hope the projectiles were full cans of Bud Lite ;-) I've threatened to build exactly what your pictures show, but never came up with the right barrel. Of course it would not have to be stainless steel.
H.W.
Click to expand...

Usually just used cans full of rocks, tennis balls and water bottles worked well too. That's back when I was drinking BMC beers (although I am now ashamed to admit it). :)
 

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