SpudGuns

I have told several people that I would put instructions for building a Spud-Gun, on this web-site. Here is my way of way of doing it.

I recommend using only ABS parts unless you buy a rifled barrel in which caase it will have to be PVC. ABS cannot be rifled. I am aware that PVC is pressure rated and ABS is not. I am also aware that if you hit a PVC fitting with a hammer it will shatter and ABS will not even if you use a sledge hammer.

Disclaimmer: Use this information at your own risk. Spud-Guns are a lot of fun but are potentially very deadly at close range. (Note the holes in the target and the ballistics info above) I assume no responsibility for anyone elses actions. A spud gun is not classed as a firearm but treat it as one.

List of Materials and order of assembly:

1. 4" Clean-Outut and Plug - female female

2. 5" or 6" of 4" pipe

3. 4" x 4" x 2" wye Assemble with the wye pointing rearward

4. 5" or 6" of 4'pipe ( same as second item )

5. 4" to 2" reducer or 4" to 2" flush bushing.

6. 2" clean out adapter (Do not glue items 6 & 7 together, however they can be eliminated if you want to permanantly attach the barrel to the combustion chamber)

7. 2" male adapter - Cut a nail or coathanger wire so that it just fits inside the adapter.

File notches in the rear end of the barrel to make way for the nail. This keeps the potato from being pushed into the combustion chamber.

8. 2" x 5 foot pipe. Note: you can make the barrel any length you want but the 5 foot length works well with this combustion chamber

9. 2" clean out adapter with plug.

10. Piezo-electric barbecue igniter ( get the kind with push-on terminals for both contacts.)

11. ABS cement

12. Quick setting Epoxy

13. 6 feet of half inch PVC pipe for a ramrod.

Clean and de-burr mating parts

Coat both mating surfaces of a joint with cement and push together while turning one piece a quarter turn. Some of the cement works very fast, so don't waste any time.

Drill a hole through the center of item 9 plug, the diameter of the igniter body.

Cut off the retaining ears of the igniter and insert through the hole in the plug

Attach a piece of stiff copper wire ( I use #12 ) to each of the igniter contacts using either the push on contacts or solder directly to the igniter contacts.

Epoxy the igniter to the plug being careful not to get epoxy inside the igniter.

Cut and bend the wires as shown in the photo. Gap about 3/8"

CAUTION! Once you have assembled your Spud Gun let it set for 24 hours with the plugs out to let the solvents evaporate.

To use your Spud Gun:

Trim a potato (or 1/2 of a potato) so that it is a snug fit in the barrel. Ram it down the barrel until it hits the stop.

Your igniter should already be in place.

Spray some hair spray into the rear of the combustion chamber and quickly screw in the plug. Aqua Net seems to be the spray of choice. DO NOT USE GASOLINE !!

The amount of spray depends a lot on temperature. More when cold, less when hot. Usually between 2 and 6 seconds.

Press the igniter button to fire.

Don't allow anyone directly behind the spudgun. I have seen the breech plug blown out several times.

Make sure the breech plug, igniter plug , and barrell are screwed in all the way, but only finger tight. I have had a nasty burn from an igniter plug that was not screwed in far enough.

If your spud gun is going to be unused for a while, remove the rear plug or the hairspray will glue it in making it very difficult to remove. If it does get stuck, soak it in water for several hours.

Keep it pointed in a safe direction