Spud Gun Ignition System

[Callipygous]

thats for a gas one. easier to build, less performance. the one i told you about will shoot farther but requires more effort with each firing and more work building it.

 

 

oh, and as it mentions on that site, make sure you use schedual 40. other stuff pops sooner.

[akcapr]

the only patato guns that exist are gas powered- if its on explosive then its a cannon!

[Callipygous]

compressed air.

 

or does that fall under the defintion of "gas powered"?

[akcapr]

well yes. ANd im very sure combustin-gas spud guns are more powerful than pressure, the same at most. Combustion is powerful stuff.

[Callipygous]

im almost positive your wrong about that.

 

i think you would be very hard pressed to find a propellent powerful enough, and accessible enough, to achieve the same results as with compressed air.

 

i have messed around a little with both. the only gas one i have seen or used was downright pathetic. the most it could get was 75 yards or so. the one i built in my back yard (compressed air) would shoot a spud straight up and leave us enough time to have the next round loaded and on its way to ready before the first one came back down. this thing put a hole in my buddy's fence.

 

i have seen models for compressed air that claim distances of up to a half a mile. the most i have ever seen or heard of from a gas powered model was about 150 yards.

 

if you have evidence to the contrary i would love to hear it.

 

 

(70 psi is powerful stuff too. i suck at this kind of math, but could someone proficient in chemistry and and physics figure out if that much is more or less than what you can get with hair spray? about as far as i can get is 70pi pounds of pressure on the back of the spud about 220?)

 

 

all the sites we found with explainations of how to calculate things like muzzle velocity wanted us to use those little things you make in geometry class with a straw taped to a proractor and a washer on a string to figure out how high it was going. we could never figure it out because on the average firing we would all lose site of the thing before its peak. we would all spend a while staring at the sky to make sure we werent gonna get a spud in the head when i finally came back down.

[akcapr]

i have seen vids of potato guns that are very powerful (gas)- u cant denie that properly made, a gas spud gun can be very powerful.

[Callipygous]

yes, but everything i have heard and experienced says that pneumatic spud guns leave them in the dust.

 

 

this site provides some info: http://ffden-2.phys.uaf.edu/211.fall2000.web.projects/J.%20Jones%20and%20T.%20Kenny/Propellants.htm

 

i certainly wouldnt call it reliable though : P

 

i would also like to note that the site suggests PVC for pneumatic spud guns because its pressure rated while ABS is more impact resistant. while this may be true it is still highly recommended that you use ABS because the other side of ABS being more impact resistant is -thats because its soft! this also means that when your spud gun pops, if its made of PVC it explodes like a grenade. if its ABS it rips like a paper bag.-

[akcapr]

maybe, but i kno ppl with gas ones than can shhot through garage doors

[jowrose]

ok, i've made 5 different potato guns:

1 pneumatic

2 Hairspray/Deoderant

2 Butane

 

first off, the pneumatic. It is easily the most consistent of the 5, it fires every shot (ok that's kinda obvious) as there's no problems with ignition. It has medium range (in my opinion) but the effects of firing it leave something to be desired (aka no loud bangs or anythign).

 

the hairspray one worked well, with the exception of ignition. it would light probably only once every 5 tries. The deoderant one had a slightly better ratio. Both these guns were very fun to shoot and could achieve better distance than the pneumatic. however, the hairspray one only lasted a few months because the barrel got fouled up from the remnants of the hairspray. the deoderant one burns cleaner.

 

the butan ones were good in theory, but miserable failures in practice. there is just no way to harness the butane gas efficiently. given, i was using lighters (kind of stupid). I've heard that using propane tanks works very well, maybe i'll try that someday.

 

And earlier in this thread people have been ripping on the anarchists cookbook. now i've read the whole thing and while it is true that there are some truly stupid ideas (plastic explosives from bleach, anyone?) there is also some worthwhile chemical content in the book. for instance, the section on thermite is what led me into the (in my opinion) fascinating chemical reaction. So dont rip on it before you've read it.

[jdurg]

The problem with the anarchist's cookbook is that it is filled with half truths. There is nothing more dangerous, in chemistry especially, to give someone half of the knowledge they need. That is why we all rip the cookbook. I've read it many times, and thankfully I was bright enough to realize that a lot of what they say isn't exactly as 'safe or easy' as they make it out to be.

[H2SO4]

Why would anyone make a spud gun out of plastic when they can use thick, steel piping. In my mind, its much safer becuse, no matter how hard that potato is jammed in there, it will always come out with out the gun exploding. Ia also imagine one could build a much nicer one out of steal, becuase you can weld/braze/solder onto it.

[akcapr]

pvc wont explode either.

[jowrose]

but using steel is so heavy... I prefer PVC because i know it's not going to explode, it's lightweight so it's easy to carry around, there are a ton of very easy options that one has (for example, it's very easy to make interchangeable parts, such as a perpendicular handle for the trigger). When you are using relatively low pressure (as in a potato gun) it's better to stick with PVC i think.

[Walden]

Okay. I've never made one of these before and I have about 3 week till I leave for school and I'm kind of bored.

 

Should I make a compressed air or a hairspray spudgun? Also, what's the best site to read for directions on how to make it?

[jowrose]

google searching is usually the best way. there are inumerable ways to make a spud gun, but there is a rule of thumb: compressed air is more reliable while hairspray/deoderant is more powerful (and make a better sound when shot... ). Usually, PVC pipe is used for construction but someone earlier on this thread has mentioned his intentions of using steel. I hope he posts when he is finished, i would like to hear the results. One thing to keep in mind is that when building the gun, be sure to have a good barrel-to-combustion chamber ratio. Obviously, the higher the ratio the farther the potato (or whatever the hell else you shoot; i've heard of people shooting frozen birds out of guns...) will fly. Up till a certain point, of course.

 

3 weeks to school, same here.

 

from now on, no more mentions of school... school sucks...

[akcapr]

i made one from an empty 2 liter and a steel fence pole ductaped toghether. id just fill the empty bottle with propane from my stove for few seconds (i figured out how long u have to hold it over the stove to get the right mixture) then id attach it to pole barrel, then i stuck a like lighter igniter (u kno the gun type ones), extended the wires and just stuck the end in the bottle throo a hole i made.its really cool but really simple i just tilt it up agains something. its liek 2 feet long but shoots like 70 yards. and also, pack the projectile in there tightly, the tighter it is the more powerful cuz theres more pressure and itr combust faster.

 

and also- no more mentioning skool.. ugh

[jowrose]

Empty 2-liter bottle?! with propane?! jesus you are going to blow your hand off soon. How on earth does the bottle not just explode? Wow you have more guts than I would...

 

While in theory any combination of combustion chamber and barrel will work, I have found that PVC pipe is the most practical and durable material around. It is easy to construct with and will easily withstand any blasts from hairspray, deoderant, propane, butane, etc...

[H2SO4]

jowrose, im not going to make a steel spudgun, because i havent enough space. Im sure my neighboors will call the cops.....douche bags.

 

 

Anyway, I have made some small mortars for shooting small, soft objects. The mortars consisted of a one inch copper pipe, with a fuse hole and one capped bottom. I loaded a few grams of lift powder and it shot stuff pretty good.

 

I probaly wouldnt use this in a big "spud gun" becuase i have found solid fuels like this to explode when i least expext it or something. I m sure gasses would be better.

 

 

But ya, if i were to build one, i would have to make it realy burly. It would have a 4 foot steal barrel, with the rest of the frame made from light weight aluminum (wait, an aluminum four foot barrel would be awesome1 think, no rust, light weight, wont burn, machineable, and METAL!)

 

 

I would have a connection for a screw in propane tank connected to the frame with a regulator and pre-mixer (like a blowtorch has, and bunsen burner). It would have a piezo electric igniter (not a hand one, like the automatic ones on new gas barbeque's. Basicaly thats all, it would be nice. If you havent nticed, i lovemaing things with metal.

 

 

Jowrose, i also dont want to talk about school. Three short ass weeks left, and were back in for 9 months. This will be my first year in high school, and everyone seems to think im nervous, but im not, im just pissed i have to go back to school for nine months.

[akcapr]

jowrose, pet bottles can hold alot of tension. try it urself. and if it did rupture it would burn me at most.

[H2SO4]

Id imagine there pretty flexible also, so if they did explode it wouldnt be like extreme shrapnel flyin eerywhere.

[insane_alien]

Hydrogen and Oxygen also work well as a propellant but it can take ages to get enough by electrolysis

[jowrose]

yeah i'll try out the 2 liter sometime. And aluminum would be the ideal metal for a spud gun, like h2so4 said it doesn't rust (well it does a little, but it actually makes the material stronger) and it is lightweight. the only drawback is the relative expensiveness of aluminum when compared to pvc. yes, i've heard of using propane tanks and regulators attached straight to the chamber, paintball-gun style. very good idea, i'm sure it will work well.

 

gonna be a freshman? yeah highschool's not so bad, hell of a lot better than middle school. at least for me. junior year for me this year.

[H2SO4]

insane alien, using H2 and O2 would be suicide. Mixing any of these fuels with O2 would be suicide.

 

YA im going to be a freshmen

[jowrose]

how so? the suicide part not the freshman part

[H2SO4]

when you mix pure O2 with fuels suchs as hairspray, H2, propane, it will explode. Try it. Put some proane in a balon along with lots of O2, put some kind of fuse on it, light it and run.