Step 1: Parts and Materials
It is a good idea to use schedule 80 PVC for your project.
For this project I used 4" PVC for the chamber and 2" PVC for the barrel. These pipe sizes can be changed based on availability.
Other important pieces are the :
4" cleanout with cap (Top right).
4" to 2" reducing coupling (Top Left).
4" x 4" x 2" coupling w/ sweep 90' (Middle)
2" cap (middle right)
PVC cleaner and cement
Not pictured : a BBQ grill igniter (pushbutton type)
Step 2: Chamber Assembly
Using your 4x4x2 and cleanout test fit the parts together and prep the PVC cleaners and glue. Cleaning and gluing are important because the potato gun builds quite a bit of pressure when it fires. (Pictures 1 & 2)
The cleanout and cap will fit right into the 4x4x2 coupling.The 2" sweep should curve away from the cleanout when it is installed. glue these pieces together and you have created the handle and gas chamber. The cleanout will be where we fill the gun with hair spray. (picture 3)
Next step is to add a 2" piece about 5" long to the sweep. Picture 4 is an example of how not to cut PVC (Ha ha ha) Picture 5 shows the 2" piece being inserted into the sweep.
Picture 7 shows installing the 2" piece into the sweep and putting the 2" cap on the end. This 2" cap will serve as the trigger assembly.
Picture 8 & 9 illustrate cutting a 12" piece of 4" pipe and inserting it into the coupling. The chamber is almost complete.x
Step 3: Trigger Assembly
Using a 3/4" paddle bit, drill a hole in the end of the cap. This hole will allow the BBQ igniter to fit perfectly into the cap.
Picture 4 & 5 show the right area for the ends of the igniter to be. It's a good idea to try and keep the sparking ends of the ignitor out of the chamber, Spraying these pieces with hairspray might affect the spark.
As an atempt at a better seal I wrapped all connections with duct tape!
Step 4: Barrel Assembly
Attach the reducing coupling to the 4" chamber. This is where the barrel attaches to the chamber. Next cut the 2" at about 3' and secure it to the reducing coupling.
Step 5: Loading the TATER'
With an item to use as a ramrod, measure the distance of your barrel and mark the rod so the potato remains in the barrel and does not fall into the chamber.
Select a potato that fill completely fill the barrel, use the ramrod to shove the potato down the barrel and you are ready for the fuel.
Step 6: FUEL !!!!!!!!!!!!!!!!!!!
Opening the cleanout spray the hairspray into the chamber for about 3 - 5 seconds, (Iwould start on the shorter side and work your way up.) cap the cleanout and BOOM !!!!!
Step 7: A Word of Caution!
If you do not follow the PVC Glue manuf. directions about waiting the 24 hours for the glue to dry there is a possibility that the fumes from the glue would be enough to lob a potato through your soffit on your backporch. BE CAREFUL.