How to make a spud gun (For noobs who dont search forums)
Posted: Tue Dec 12, 2006 6:57 pm
A potato gun sometimes called a spudzooka or spud gun is weapon that can launch spuds at over 200 ft/s. It is a propellant based gun that uses any propane based aerosol as a propellant (most experiments use hair spray, for it is inexpensive and easy to use). The way it works is propellant is injected into the combustion chamber and ignited with a BBQ sparker, as the gas expands it pushes the potato up the barrel and out of the gun.
Building a potato gun is fairly simple provided some basic tools are available. The most basic potato gun consists of three main components: a combustion chamber, a barrel, and an ignitor. The combustion chamber and the barrel are usually constructed out of pressure rated PVC or ABS piping and the ignitor can be any type of sparker, but most potato gun experimenter's prefer to use BBQ ignitors, for they provide a large and effective spark.
Parts
# 2 feet of 2 inch dia. PVC or ABS pressure rated pipe
# 1 foot of 3 inch dia. PVc or ABS pressure rated pipe
# screw off end cap for 3 inch pipe (note: clean out plug may be used)
# slip to threaded 3 inch fitting
# 3 to 2 in reducer
# PVC or ABS cement (note: do NOT mix PVC pipes with ABS pipes or fitting, only use PVC cement on PVC and ABS on ABS)
# BBQ ignitor
# 2 drywall screws
# hair spray
# plenty of spuds
Assembly Instructions
1. Cut pipes to correct length's with a hacksaw
2. Glue the barrel and the chamber to the reducer as shown in the diagram. (if PVC is used don't forget to apply primer first.
3. Close off the end of the chamber with the fitting and screw-on end cap or the drain plug cap.
4. Screw the drywall screws through the sides the combustion chamber so there is about a 1/4 to 3/8 inch gap
5. Connect the sparker to the drywall screw and make sure it fires properly, if no spark fires move screws closer and re-test.
6. Bevel the end of the barrel so that the potato will be cut to size when it is loaded. Beveling can be done with a Dremel or if one is not available a file can be used.
7. Let cement dry for about an hour (this time can be used to go buy some spuds!!)
Firing Tips
Caution: Only fire in open spaces far away from human life
1. Load the gun by cutting a large enough potato in half and then cutting it to the right size by pushing it into the barrel of the gun and letting the gun cut the potato's shape. If the potato is too small the potato will not go very far, for most of the gas will escape. Providing a good seal is the key to distance spud launching.
2. Get a stick that can be used to muzzle load the potato. Measure out how far on the stick the potato has to be pushed down to be right before the combustion chamber and push it down to that level.
3. Unscrew the back and fill with propellant. I like using pure propane from a blowtorch, but if one isn't available then hair spray can be used. This is the trickiest part of all. The correct mixture of gas to air has to be present for the gun to fire. Experimenting is the best way. One thing that is important to remember is that the gas needs oxygen to combustion therefore after each time it is fired air must be allowed into the chamber.
4. Good Luck.
Source: http://www.mshamash.com/spud/spudgun1.html
Building a potato gun is fairly simple provided some basic tools are available. The most basic potato gun consists of three main components: a combustion chamber, a barrel, and an ignitor. The combustion chamber and the barrel are usually constructed out of pressure rated PVC or ABS piping and the ignitor can be any type of sparker, but most potato gun experimenter's prefer to use BBQ ignitors, for they provide a large and effective spark.
Parts
# 2 feet of 2 inch dia. PVC or ABS pressure rated pipe
# 1 foot of 3 inch dia. PVc or ABS pressure rated pipe
# screw off end cap for 3 inch pipe (note: clean out plug may be used)
# slip to threaded 3 inch fitting
# 3 to 2 in reducer
# PVC or ABS cement (note: do NOT mix PVC pipes with ABS pipes or fitting, only use PVC cement on PVC and ABS on ABS)
# BBQ ignitor
# 2 drywall screws
# hair spray
# plenty of spuds
Assembly Instructions
1. Cut pipes to correct length's with a hacksaw
2. Glue the barrel and the chamber to the reducer as shown in the diagram. (if PVC is used don't forget to apply primer first.
3. Close off the end of the chamber with the fitting and screw-on end cap or the drain plug cap.
4. Screw the drywall screws through the sides the combustion chamber so there is about a 1/4 to 3/8 inch gap
5. Connect the sparker to the drywall screw and make sure it fires properly, if no spark fires move screws closer and re-test.
6. Bevel the end of the barrel so that the potato will be cut to size when it is loaded. Beveling can be done with a Dremel or if one is not available a file can be used.
7. Let cement dry for about an hour (this time can be used to go buy some spuds!!)
Firing Tips
Caution: Only fire in open spaces far away from human life
1. Load the gun by cutting a large enough potato in half and then cutting it to the right size by pushing it into the barrel of the gun and letting the gun cut the potato's shape. If the potato is too small the potato will not go very far, for most of the gas will escape. Providing a good seal is the key to distance spud launching.
2. Get a stick that can be used to muzzle load the potato. Measure out how far on the stick the potato has to be pushed down to be right before the combustion chamber and push it down to that level.
3. Unscrew the back and fill with propellant. I like using pure propane from a blowtorch, but if one isn't available then hair spray can be used. This is the trickiest part of all. The correct mixture of gas to air has to be present for the gun to fire. Experimenting is the best way. One thing that is important to remember is that the gas needs oxygen to combustion therefore after each time it is fired air must be allowed into the chamber.
4. Good Luck.
Source: http://www.mshamash.com/spud/spudgun1.html