Potato Cannon - V2

This cannon is a little bit more complicated than the other cannon, but it is vastly superior.

cannon v2 sketch
Want a larger image?

Here's a materials list for the chamber:

 Part Qty
 2" PVC Pipe ~2 1/2' 
 3" PVC Pipe ~2" 
 4" PVC Pipe ~1 1/2' 
 2" - 3" PVC Adapter
 3" - 4" Adapter
 2" Female Cleanout Adapter
 4" Female PVC Adapter
 4" End Cap
 Grill Ignitor
 PVC Cement
 PVC Primer
 Hot glue A few sticks 

chamber diagram

The Chamber of the cannon looks like this. As you can see i've painted it chrome to make it look cooler. Putting this together is a breeze. The 4" female adapter fits on the end of the 4" PVC pipe. First prime both surfaces to be cemented with PVC Purple Primer. Then place PVC Cement on both sides, put them together quickly (it sets fast) and hold until bond is set. On the other end you put the 4"-3" adapter, cementing it in a similar fashion. Between the 3"-2" adapter you need to place a short (1"-2") piece of 3" PVC. Start by cementing the short pice to the 3" end of the 4"-3" adapter, then cement on the 3"-2" adapter. Cement the 2" female adapter on the 3"-2" adapter. Before using make sure that all bonds are secure and set. Do this by tugging on each piece and checking for movement.

Here's a materials list for the barrels:

 Part Qty
 1 1/2" Barrel
 1 1/2" PVC Pipe  ~2 1/2' 
 2" PVC Pipe  ~2" 
 1 1/2" - 2" Adapter  1 
 2" Male Adapter  1 
 2" Barrel
 2" PVC Pipe  ~2 1/2' 
 2" Male Adapter  1 
 3" Barrel
 2" PVC Pipe  ~2" 
 3" PVC Pipe  ~2 1/2' 
 2" - 3" Adapter  1 
 2" Male Adapter  1 
 4" Barrel (not pictured)
 4" PVC Pipe  ~2 1/2' 
 2" - 4" Flush Adapter  1 
 2" Male Cleanout Adapter*  1 
*-not in visual parts reference

cannon set

Once completed the set will look like this.

Now all you have left is the end cap. The end cap contains the ignitor.

end cap blow up

end cap blow up

This part is pretty self explanatory. You have to drill a 3/4" hole in the center of the end cap. The ignitor should be able to fit in the hole, you may have to file down the parts that are intended for mounting to a grill. You need to take the cord provided with the ignitor andcut it off and solder it to the wire along the side of the ignitor. Then hotglue the cord down so the exposed metal tip is close enough for a spark to jump across. Once the ignitor is prepared simply hotglue it into place. Let it set for a while before use. If you wish you may use silicon sealer instead of hotglue.

Additionaly you can make a Y-adapter (Double barrel) that will enable you to launch two potatos at the same time.

y-adapter

All you need is a 2X2X2 45° y-junction pipe, a 45° elbow, two 2" female adapters, and a 2" male adapter. Follow the same cementing procedures as you did for the rest of the cannon.

WARNINGS

When using hairspray as a propelent avoid spraying it directly on the threads of the screws. The screws will stick together and may cause the barrel to break if you force it too much. If your barrel does get stuck DO NOT force it, instead you can use channel locks or a pipe grip which may be bought at a hardware store. These tools will give you much better leverage and will unscrew them with minimal force. Trust me, I learned from experience. You should also wash out your cannon when you're done, gunk tends to build up in it.