SPUD GUNS RULE!
So what exactlly IS a spud Gun you ask? Well, it's a device for launching a chunk of potato very far very quickly. There are various styles of Spud Guns, the most common being made of PVC and powered by a combustible gas. The usual for of the gas is any h ighly flammable airasol, such as hair spray, wd40, of ether carb spray. A potato is rammed down the barrel to a point just in front of the combustion chamber, the chamber filled with the spray, capped off, and ignited. The usual method if ignition is with a barbecue grill igntior. Other sparkers include home made devices, and coleman lantern sparkers that use a flint. This Style of gun I refer to as a "hair spray gun". Then there's my Gun..it's pneumatic, which for some people, means it uses air .There are several advantages to this gun, as well as several reasons not to build one. While the Hairspray guns are not really all that safe, and I wouldn't suggest building one (if yer crazy and hurt yourself, I told you NOT_ to make it), they are also not v ery powerful, or deadly.. well, they could kill you....but anyways. Now for the REAL spud gun!! This project can be VERY VERY dangerous, Air in itself is NOT dangerous, but COMPRESSED AIR IS! This is not a how to guide to building a Spud Gun, I have intentionally left out a few th ings (a very few things). If you intend to build a Pneumatic Spudgun, you should have some idea of pneumatic systems b4 trying this, otherwise, if you were to follow this story, as a guide, step by step, you would not have a functional gun. And you STILL could hurt yourself, so PLEASE if you are just set upon making a gun, contact me, and I will help you decide how to go about doing so, if I feel you have the experience to do this. Otherwise, dont do it, or get someone who knows how, to do the pressure sy stem for you. Now, on with my story of Building The SpudBoomer 2001!!

The first thing I did was think long and hard about this... I asked myself where I could get more info, I found it online...it's not hard to find. then I set out asking a Certified PE, with ASME certification. In english, it means he knows his shit ab out high pressure systems. Next I made a list of parts (HINT: this is where there is something missing):

  • 1 24" section of 2" Schedule 40 PVC pipe
  • 1 6' section of 1.5" Schedule 40 PVC pipe
  • 1 2" section of .75" Schedule 40 PVC pipe
  • 1 2" slip to .5" NPI bushing (Use Scd 40 PVC Pressure fittings ONLY!)
  • 1 2" slip to .75" NPI bushing (Use Scd 40 PVC Pressure fittings ONLY!)
  • 1 1.5" slip to .75" NPI bushing (Use Scd 40 PVC Pressure fittings ONLY!)
  • 2 90 degree .75" slip to NPI elbows (Use Scd 40 PVC Pressure fittings ONLY!)
  • 1 1/8" threaded valve stem style valve
  • 1 brass 1/2" to 1/8" bushing
  • 1 Solenoid Controlled Sprinkler Valve (rated at 125 PSI or above ONLY)
That's the basic parts list, the total cost for THOSE parts, not including the valve stem was around $30, and I bought them all at a local hardware store. The things I paid extra close attention to were the PVC fittings, there were 3 kinds, ABS, Pressure, and Sewer. ABS is easy to identify, it is black. The sewer and Pressure however are both made of white PVC, the way I can tell them apart is that sewer pipes have a more, flamboyant flared end to them, and the elbows are long and sweeping curves, not sha rp right angles. If I had any doubt, I would have asked someone who worked there, but the bins were also properly marked. Once I got my pipes, I got started on assembling the pressure tank. For this, I took a 24" length of PVC pipe and glued them.. a side note on glues.. The glue I used was for water systems it was a mid-fast curing PVC Cement, it was clear, not blue, green, or red tinted. Before gluing my pipes I used a Commercial grade PVC pipe primer, it's a thin thin THIN purple liquid that softens th e PVC so it accepted the cement better...now back to the making of the tank...
To my 24" section of 2" Schd40 PVC, I glued the 2" bushings, one on each end. On the end with the 1/2" Bushing, I screwed in my Filling Valve assembly, this is composed of the 1/2" to 1/8" brass bushing, and the valve stem style valve, from here on referred to as the "tip valve". This tip va lve is NOT a tire valve, it looks like one, and is filled with the same tools, but car tire valve stems are NOT threaded on both ends. These valves are pretty hard to find, and are NOT found at an automotive supply store. But anyways, before I screwed it in, I put a few turns of teflon tape on the threads (both the 1/8 valve and the 1/2 bushing) then I screwed them all into each other, as you can see.

I made certain they were quite tight, but not so tight as to damage the pipe in any way, a good strong arm tight, not machine tight. I set this whole thing aside, and went to work on the next project, connecting the valve to the barrel. First step was to make a U shaped connector, to do this I took my 2 90 degree elbows and the 2" section of 3/4" pipe, and glued them together to form a wide U shaped piece with threads on each end, then put teflon tape on them. Next, I took my val ve, and screwed one end of my wide U piece into the valves "IN" port and the other end into the 3/4" bushing attached to the pressure tank.

The next step was to make the barrel assembly. I started buy cutting a 6 foot section of 1.5" Scd40 PVC pipe. At one end of my pipe, I glued on the 1.5" to .75" r educer. (note: in the picture I used a 1.5-1-.75 reducing assembly because the store was out of 1.5 to .75 reducers). Before I screwed the barrel on to the rest of the gun, I had to sharpen the other end into a round blade, so as to cut to potato as I ram med it down the barrel. to do this, I used a shop belt sander, and gave it a very long slow blade, with a serated feel to it. I also sanded the inside of the barrel a bit to make it so that the potato would be compressed a bit as it went it. The next step was to screw the barrel into the "out" port on the vavle, and the gun was pretty much done. At this point, I set the gun down in a warm, fairly humid room, overnight. The PVC Cement cures to the point here it's solid in juts 10 minutes, but in order for it to really CURE and set up, and become string, it has to sit at least 12 hours before any pressue is applied. I went to bed.

The next morning, I went out to my shop, got my gun.. now was the time to test fill it. First I got my tire hose...this is juts a standard hose/nozzle for filling tires...I went to my air l ine, pluged it in, and set the regulator to about 20 PSI... I'd like to just say a few words about air again...air pressure can be lethal, very very lethal. You can buy a small storage tank, one that fits in your car, and used for flats, they cost like $50 and are generally very good tanks, they have a maximumstor age pressure of around 100 PSI. I have seen pictures of thee tanks after they have exploded. in the trunk of a honda civic, the tank exploded, and litterally ripped every scrap of metal away from the chasis, killed the poeple in the car, and shot shrapnel over 300 feet...this is serious stuff, and I do NOT recomend you try this, PERIOD. To make things worse, I have an aircompressor capable of over 200 PSI and a tank about 5' tall and 3' in diameter, if this were to explode, it would wipe out everything to the ground in a 200 foot radius....cool huh? well, it COULD happen, it doesn't happ en often, but it COULD, whihc is why I strongly advise you NOT to mes with this shit....anyways, back to my story. I set the regulator at 20 PSI and filled the gun, this served a few purposes. Mainly to test my joint, if they were weak, and the 20 PSI bro ke them, I'd feel fairly safe, and they would probably juts pop and the presure would go into the air. At 100 PSI, if the joint were to break, I would be dead. so, the joint held. The othr thing this did was test the vavles, they also worked as they shoul d. Next I began filling it and fireing it gradually, in 10 PSI increments. When I finally got to 100 PSI, I used a real potato, and fired. to my delight, the potato went well over 250 yards, over my fence, and into the next property. SUCCESS!!..

This is not the end of my story however...at this point, I had been fireing my cannon by holding a 9 volt battery in one hand, and shicking myself to get the 2 sollenoid wires to make the circuit. I got tired of this, and decided to make a trigger device. This could have been basilly ANY momentary on push button circuit. I decided to add a safty/off switch as well, so I didn;t accidently fire, ot drain my battery. I dont have the details right now, maybe someday I will draw up scemeatixs for it, but it's such a basic circuit, I'm too lazy. Ok now, that's the end of my story, if I inspire you, please think twice...I don't want to have to defend myself cuz some idiot fucke d up
Thanks!
-GreySoul