PVC Pipe Spudgun Guide
PVC is an all around universal pipe that can be used for a number of projects, most obviously plumbing. But the real beauty of PVC pipe is its versatility: it can be used for hobbies, toys, musical instruments and, of course, potato launchers. In buying your PVC pipe, two things are of import: Schedule and Diameter. Here's the basics for understanding PVC pipe to build your air cannon.
PVC is the common term for Polyvinyl chloride. There are many uses for PVC, besides the familiar pipe for spud cannons. As a hard plastic, it is used as vinyl siding, magnetic stripe cards, window profiles, grammophone records (which is the source of the name for vinyl records), pipe, plumbing and conduit fixtures.
PVC Pipe has is usually measured by its internal diameter, that is the space between the walls of the pipe. So a 1.5" pipe has room for a spud 1.5" wide inside. The schedule is the thickness of the walls of the pipe. Standard PVC pipe is Schedule 40 (SCH 40), and SCH 40 is what is used for constructing your spudgun. You may find pipe marked "DWV" which stands for "Drain Waste Vent" pipe. DWV pipe is used for water outlests only, and is thus not subject to pressure or used in pressurized systems. It's advisable to stay away from DWV pipe, since most is not rated for pressure.
The pressure rating for PVC pipe is usually around 300 PSI, but in building a spudgun, this type of pressure is rarely acheived - most potato cannon only go to 120psi, max. That's plenty of pressure to lob a potato across the park.
The best place to purchase your PVC pipe is probably a big-box home improvement store like Home Depot or Lowes. They have a good selection of connections and pipe, and the staff there can usualyl cut a pipe if it is too long. Most pipes come in 10 foot sections.
PVC Pipe Musical Instruments
If you're ever interested in seeing what else PVC pipe can be used for, try making it into a musical instrument. Large Diameter PVC can be used for making drums or low-sounding phones. The Blueman Group are known for their creative uses in PVC-based musical instruments. The Drumbone is an instrument made from large-diameter PVC; is uses two movable sections to alter the pitch. One Blue Man plays the instrument with drumsticks, another moves the horizontal slide, and a third Blue Man moves the vertical slide. The Drumbone is only used in the song of the same name, which is an audience favorite. Blue Man Group used a special Drumbone shaped like the number 4 for the Intel Pentium 4 commercials.
I've made a didgeridoo out of PVC pipe - it's 5 feet long with a swooping 4 inch bell at the bottom for a very nice low sound. The bell helps amplify the sound and changes the pitch slightly. The PVC didgeridoo always gets looks and sounds great when you place the bell into a ceiling corner of a room. To make it, I simply put together pieces for a mouthpiece, connectors, and a length of pipe. No glue was necessary, though it could use a piantjob.
The beauty of PVC lies in its versatility. It can be used to make mini spud guns or micro spudzookas, and it can be used for large-scale fruit launchers. Think pumpkins here! The common design principle of CHAMBER-VALVE-BARREL is applied to making a spud cannon of small or lage size. As long as you make your proportiaons similiar, the device is pretty much going to work. PVC spudguns can be used to launch marshmallows, t-shirts from a t-shirt gun, or even pop bottles!
Be careful, and have fun! Check back here later for updated diagrams and a better PVC guide.