BOOOF!

April 12, 2012 3:09 PM

The Spudgun Technology Center, for all your spudgun needs. Many of us have probably built a spudgun (aka: potato cannon, spudchucker, potato launcher) before, most likely something along the lines of this basic model. Perhaps some of us have even built pneumatic cannons, or perhaps experimented with different fuels. The Spud Gun Technology center takes spudgun engineering to levels far beyond your wildest adolescent dreams. (Unless you went to this site as an adolescent. It's a true Web Classic.) Read on for a more about these tuber-launching funmakers and TSTC.

Never built a spudgun before? Well, there are plenty of places on the web that will tell you how to build your own, whether you want to build a combustion powered launcher or the slightly less common pneumatic launcher.

Of course, that might not be your first concern. Potato cannons offer a lot of bang for your buck, but there are certainly legal and safety issues that must be considered. You also might want to take more of an engineering approach, and the above-mentioned Spudgun Technology Center (charmingly Web 1.0 though it may be) certainly has you covered with a discussion of construction materials, ignition methods, and plenty of other considerations. They even have a store where you can buy advanced components like rifled barrels, custom valving, and ignitors.

Fun for the whole family!

posted by Scientist (25 comments total)

The legal section is basically a turd.
posted by ryanrs at 3:19 PM on April 12, 2012

Well, if you want a slightly more in-depth treatment of the legality of potato cannons (which I think even as a kid I considered kind of a grey area at best) there's a bit on wikipedia which discusses local laws in the U.S. and other countries. Most other links on the subject are either repostings of the ATF letter at TSTC or "Think Of The Children!"-style local news articles. In any case I really didn't intend for the post to hinge on that link, but I'll admit that there doesn't seem to be a lot of great information out there besides "you should think about checking your local ordinances".

I'll go away now, happy spudchucking everyone!
posted by Scientist at 3:34 PM on April 12, 2012

I made one to launch a weighted pouch with a line into very tall trees I need to climb. It works wonderfully, and it's pretty amazing what you can do with a bike pump and a few cheap plumbing parts. Plus, you have to admit, they're awesomely fun.
posted by Red Loop at 4:05 PM on April 12, 2012

"Why do they call you Spudgun?"

"Give me a potato and I'll show you."
posted by Lentrohamsanin at 4:15 PM on April 12, 2012

The pneumatic version is isomorphic to a seismic air gun which can be bought used for a little more than the value of the scrap metal.

This is a hazardous hobby. Think fireworks. Probably not for kids unless they are unusually responsible. Or at least a helluva lot more responsible than I was with fireworks.
posted by bukvich at 4:15 PM on April 12, 2012

Haha, I loved these things growing up.

For me, I think the high (low) point was when we cut up some wire coathangers, and fitted them with cardboard cones on the tail to make sharpened 6" metal darts. We then inserted a smaller PVC pipe inside the mouth of the potato cannon proper, and held *that* in place with duct tape. I am sure you can tell where this story is heading.

I am certain (now) that this was not legal, and when we blasted said dart through a plank of wood at 10m distance we realized it then, too. I'm just glad we had the sense to dis-assemble the thing before our parents noticed.

"So, what are you kids up to out here??"

"Nothing..."
posted by Arandia at 4:59 PM on April 12, 2012

A few years ago I built a pneumatic model which could launch a potato over the tops of the pine trees at the edge of my yard. But an unexpectedly cool thing I found to do with it was to use a styrofoam coffee cup for wadding, tilt the barrel back, and fill it with water-instant water cannon! In my younger and far more foolish days I would have been tempted to try it with gasoline and some sort of remote firing and ignition system, but fortunately old age brings at least a modicum of wisdom. I may have to break it out and take some video of it in action if I am ever bored.
posted by TedW at 5:05 PM on April 12, 2012 [1 favorite]

man this makes me miss living in the woods so hard. i love building stuff for exploding things.
posted by beefetish at 5:07 PM on April 12, 2012

Two spud gun stories:
1) Like TedW, we discovered that water on top of wadding (in our case, warm beer over an already-loaded potato) make for quite the spray. In fact, if you do it right, you can defoliate trees in a nice neat little cone.

2) In 1995, a couple guys I knew from one class invited me on a road trip to the Grand Canyon over spring break. We took the spud gun, of course. After launching a couple from one of the overlooks to the next outcrop of rock, a ranger pulled up in his Jeep.

"You want me to write you up for feeding the wildlife? Don't want to get the animals accustomed to human food."
"Sir, they're landing so far away from people the animals won't have any..."
"Would you rather I write you up for discharging a firearm on Federal property?"
"Nossir."

We put the potato gun away.
posted by notsnot at 5:23 PM on April 12, 2012 [5 favorites]

TedW, I can confirm that filling a pneumatic potato cannon with gasoline and then discharging it over a raging bonfire is indeed awesome.
posted by NickO at 6:17 PM on April 12, 2012 [2 favorites]

Quick question before I go any further in the design process: would using propane combustion for a tennis ball gun result in high-speed, rapid-fire flaming balls? Because if not, I don't think I'll bother proceeding.
posted by Mary Ellen Carter at 6:43 PM on April 12, 2012

The ideal fuel/air mix with propane is sufficiently difficult to achieve reliably that it's not worth it in my opinion. Believe me, I've tried. The contraption worked, but it was mostly notable from an engineering perspective rather than a performance perspective. And I think there is actually a shorter flame duration with pure propane than with the less refined fuels normally used. Now, if you soaked the tennis ball in gasoline that would probably work. You can definitely get rags to catch fire that way, but my friends and I were never so stupid as to use a flaming projectile that had any significant range.
posted by Scientist at 6:58 PM on April 12, 2012

Stupidest thing I ever did with a potato gun was put lit fireworks down the barrel (with paper wadding in place beforehand) and then shoot them off straight up. Worked brilliantly as intended, still probably a very stupid thing to do.

Best thing I ever did with a potato gun was mount one on the front of a Mardi Gras float (the float was a steampunk pirate airship) and use it to fire glitter into the air in the middle of the French Quarter on Mardi Gras day.
posted by Scientist at 7:01 PM on April 12, 2012

So, has anybody here ever had a chamber explode and send a spinning shard of PVC through the skull of next door's newborn?

Just asking.
posted by flabdablet at 7:09 PM on April 12, 2012

Well I always avoid using them near newborns, but I did once have a barrel shear off on a pneumatic gun when I dumped the pressure. That was pretty hairy.

Overall though these are pretty low-pressure devices, the combustion ones anyway. As soon as the gases start expanding the potato starts moving. I'd argue that the pneumatic ones are more dangerous because the tank has to actually *store* all the pressure before you pull the trigger/push the lever. I've always felt vague unease when snuggling my arm around the tank of a charged pneumatic potato cannon.

Frankly they just aren't very safe things and that should be understood by anyone who wants to make/use one. They're also not terribly dangerous as long as one is a bit careful, though. You can find news reports of people badly injuring themselves with potato guns, and there are probably plenty of more near/slight injuries that don't get reported, but I've made lots and used them lots and so have my friends and we never got hurt so, um, no problem I guess?

Some things that are fun are also dangerous.
posted by Scientist at 7:46 PM on April 12, 2012

I am 43. I have never seen a potato gun before today. I skimmed over this thread this morning and thought, "I'll take a look later on, maybe my 10 year son & I could get some fun outta this".

I then drove to a friend's place, where her 13 year old son was coincidentally testing his new potato gun (but had run out of potatoes so was using onions instead).

I instantly realised I don't want one... I NEED one.

If you want me, I'll be in the shed with PVC pipe, tape, a tin of spray deodorant, a barbecue lighter, and the contents of the vegie bin.
posted by malibustacey9999 at 7:53 PM on April 12, 2012 [1 favorite]

So, has anybody here ever had a chamber explode ...

One of the reasons I went with a pneumatic version was so I could control the pressure. I pumped it up to 120 PSI which is well below the specifified pressure rating on the 2 inch schedule 40 pipe I used.
posted by TedW at 8:56 PM on April 12, 2012

I worry a lot more about the connections than I do about the pipe itself. Potato guns have all kinds of fittings attached that were never meant to be glued into PVC. Things like nails, screws, sprinkler valves, steel ball valves, brass high-pressure tubing... that's where I worry about blowouts, especially with the pneumatic guns. I really doubt if the combustion ones ever get close to 120 psi before the potato starts to move and the pressure begins to vent, so despite the fire I'm not very scared of them.

Holding all that pressure in the gun though (120 is about as brave as I ever was) is a little worrisome to me. With the failure I had, I think what happened is that when my friend's granddad grabbed hold of the 1" brass ball valve that we had epoxied into the gun between the chamber and the barrel, and gave it a good hard twist to open the valve nice and quicklike, he put some shear stress on the epoxy joint. The pressure inside did the rest and the whole barrel went flying. Nobody was hurt, as it was of course not pointed at anyone, but still it was a scary experience. I'd be more cautious about making a pneumatic gun nowadays, I'd want to do more R&D to build something nice and strong whereas with the combustion ones I'm happy to slap one together in an afternoon and shoot it the next day with no worries.

The pneumatic ones are so much more reliable though, and they fling the potato quite a bit harder. They're a lot of fun and the engineering challenge is a bit different which is fun too. I'd want to use a solenoid-controlled valve though now so that I could have a remote trigger (which would be cool in and of itself!) and I wouldn't use a metal-to-plastic interface.
posted by Scientist at 9:20 PM on April 12, 2012 [1 favorite]

i scanned this post earlier today, and just now was puzzled when I saw it, having misread the word "spudgun."

What on earth is a spudgeon, I wondered to myself, and why is this post just like the spud... gun...


oh.


I still want to know what a spudgeon is.
posted by mwhybark at 11:28 PM on April 12, 2012

Isn't that one of those genetic engineering things where they put fish genes into potatoes?
posted by flabdablet at 12:51 AM on April 13, 2012

Spud guns are fun but pumpkin cannons are where the real action is at.
posted by bap98189 at 2:14 AM on April 13, 2012

This is bringing back memories. I cut my teeth on this website back in high school. Building a spud gun was the first "maker" project I ever attempted that actually worked the way it was designed. Too well, in fact, and to this day I'm not sure why my parents were never concerned about it.

I had two major failures that, in hindsight, should have left me with a bleeding head. First, the firing chamber I used was a piece of PVC 90-degree elbow pipe with a threaded mate on the back of it. Unscrew the plug, fill with propellant, screw the plug back on, and then the plug would basically be pointed straight up while it was resting on your shoulder (third point - wear earplugs when large boomstick is on your shoulder). The first time I built the spud gun, I used two-part epoxy to glue everything together. I got about three or four shots off, and then the next shot there is a loud BAANGG and instead of a potato, the back end of the firing chamber is sailing over my head. PVC glue held together much better.

The second bright idea I had was to take one of those squishy stress balls and try to fire it out of the barrel. Luckily, it wouldn't go very far down the barrel because instead of launching it literally turned inside out inside the cannon, sealing the barrel with a mass of sticky goo. Only a small hole in the center of this mess of goo prevented it from overpressuring the rest of the thing.

Anyway, don't build these, they're dangerous, but two cool things I learned to do that you should totally try: skeet shooting and skipping spuds. I had a friend with a pile of old AOL CDs throw them one at a time in the air, and I got good enough to nail them with the spud. Proudest moment of my life at that point. Also, if you fire the spud gun almost level with the ground in to a calm body of water, you can make the potato skip across the pond for about thirty yards or so.
posted by backseatpilot at 4:44 AM on April 13, 2012

I'd want to use a solenoid-controlled valve though now so that I could have a remote trigger

That's how I did it, with 2 sprinkler system valves in parallel. They are operated by 24v DC, so I wired up 3 9v batteries in series and put them in a box with a lighted on-off switch to indicate the system was armed and a momentary on-off switch for firing. The whole thing was mounted on a frame of 2x4s so it was aimed and fired without having to hold it.
posted by TedW at 4:59 AM on April 13, 2012

Loud shots from the big spudgun
posted by Thorzdad at 5:18 AM on April 13, 2012 [1 favorite]

Proxied pumpkin cannon link for people outside the US.

I do not understand why Popular Science thinks it's a good idea to force-redirect popsci.com to the utterly non-equivalent popsci.com.au from my house.
posted by flabdablet at 7:29 AM on April 13, 2012 [1 favorite]