This is my Instructable on a Pneumatic (air powered) Projectile (potatoes, corn cobs, etc.) Launcher. This is basically a Potato gun, or spud gun as some call it. This is a fun, easy project and can be finished in about 10 minutes (excluding drying/curing time)
Step 1: Materials and Tools
The things you will need...
4 or 5 ft. of 11/2" ABS Pipe
Some small pieces of 11/2" ABS
2 ft. of 3" ABS Pipe
A 11/4" Ball Valve
2 11/4" threaded to 11/2" adapters.
1 11/2" to 3" Reducer
A 3" Cap OR A 3" ABS cleanout adapter
A Schrader Valve
A pipe wrench
Step 2: Fitting the Pipes Together
First off get your 11/2" ABS pipe and cement it to the one threaded adapter. That is your barrel, now you need to work on the air chamber.
Take your piece of 3" ABS pipe and attach the reducer followed by a small piece of 11/2" ABS and the other threaded adapter. Now you need to add the Schrader valve to the cap or the cleanout adapter. I did this by drilling a hole slightly smaller than the valve and pushed it through then put a lot of ABS cement around the valve. Next, attach the 3" Cap or the cleanout adapter.
That gives you the basic PPL.
Step 3: Getting Ready to Fire
Let the PPL sit for at LEAST 24 hours, but 48 would be better.
When you are ready to use it make sure you are in an area outside of a city, because lots of people don't like having stuff fly through their backyards. Use common sense when using this PPL.
DO NOT EVER POINT AT ANY HUMAN OR ANIMAL! THIS IS CAPABLE OF KILLING WITH THE RIGHT AMMO!
To make this usable just screw in the two threaded adapters and fill it up with an air compressor or bike pump. If there are any leaks at the threads slowly open the ball valve and take out the air chamber. Get some Teflon tape and put some around the threads then screw it in again.
When you are sure everything is good and sealed grab a potato or apple or corn cob (or anything else that will fit) and push it down to the bottom with the ball valve closed.
Step 4: Firing the PPL
Pressurize the air chamber (with very little air, you can add more and more air each time) and go to a safe place with no people in front of you. To fire pull back the ball valve and brace yourself. If all went well you should be able to see a projectile launch just a few feet, which is good, because you were supposed to pressurize it just a bit.
Now go pressurize it again, but a bit more this time. You can use a tire gauge to check the air pressure when you are filling it up. Remember to take it slowly, especially if it has been sitting for a while or you just made a modification.
Step 5: Ammo and Targets
Here are some examples for fun ammunition!
Corn Cobs - These work great, they fit nicely and are biodegradable! They also taste delicious, so next time you have corn, this is how you can get rid of the cobs.
Water - Surprisingly fun and is probably the cheapest ammo possible. On a hot summer day shoot it straight up in the air and it mists down and is very refreshing.
Snow - By pushing snow into the barrel and compressing it to get as much in as possible it makes a nice fireworks effect when you fire it.
Stick/Broom Handle - These are very cool to shoot and can penetrate wood targets easily. Before you put it in it is best to put in a wad of cloth such as a rag because this pushes the projectile faster.
Here are some fun targets!
Plywood - This make a fun target because you can experiment to see what ammo has the most power.
45 Gallon Drums - These are big and easy to hit, you can also use them to prop stuff up.
An open field - Just launch some stuff you don't want to recover into a field, just make sure it won't hurt the environment.
Old cars - Got an old car thats just sitting on your property? Why not shoot stuff at it with 100 PSI?
Step 6: Optional Mods/Upgrades
Upgrade 1: Pressure Gauge
I decided to add a air pressure gauge I got at Lowe's. To do this I drilled a hole into the reducer AND the ABS pipe to give it extra strength. The ABS is soft enough that you don't need to tap it, but if you want to you can. After you screw it all the way in put some ABS cement around it and let it sit for at least 24 hours.
Upgrade 2: Different Barrel
If you want to you can add a bigger or smaller barrel, because it just screws on and off. To do this get a piece of ABS pipe the size you want and a threaded adapter of the proper size. Then glue it all together and test it out.
Step 7: Conclusion
This is a really fun thing to make, but don't treat it as a toy. Don't let young children use it or people who you feel are unfit in any way. Remember it is dangerous and is never to be pointed at animals or people. Use firearm safety with this because according to the Canadian Government, it is a firearm. Always be sure of your target, what is behind of your target, and what can go in front of your target. Don't let people crowd around you when you are using it, you never know what could happen.
Thanks for taking a look, I might upload a video/ pictures of it firing if the weather gets a bit better.
Step 8: Videos
Here are some videos...
Firing test 1
Firing Test 2