Frequently Asked Questions About Potato Launchers:
Probably anything you ever wanted to know but were afraid to ask has already been addressed here. Take a moment to check these over, I will try to continuously expand on this section. If you believe something should be added, changed, or is flat out wrong please let me know.
Q: The pipe I bought has SCH 40 printed on it...But it also says DWV....Is it ok to use?
A: When selecting pipe for use in building a spudgun or other type of novelty launching device, make sure the pipe has a pressure rating printed on the pipe. The typical printing on a length of pressure rated pipe will look something like this: (2" PVC pipe)
"MANUFACTURES NAME" PVC 1120 SCH 40 ASTM D-1785 NSF-PW 280 PSI @ 73F
The thing you want to look for is the NSF-PW 280 PSI (or whatever the psi rating is on that size of pipe) It doesn't matter if it is SCH 40, 80, or 120....Look for the pressure rating.
If the pipe has a pressure rating on it, it is ok to use. The reason that it also says DWV is because all ratings for the pipe must be labeled. If a piece of pipe is rated for 280 psi...It is obviously approved for use as drain pipe. There are all kinds of labels you might find. One is "cellular core". If it has a cellular core label.....dont even think about using that for a spudgun. It will eventually fail on you.
To make a long story short.....I don't care if the pipe is labeled "Blessed by Mother Theresa"....If it has a PSI rating printed on the pipe, go ahead and use it. If not, find some that is!!!!!
Q: Hey, can you rifle 3/4"....1"....2.5"....3".....4"....or aluminum pipe?
A: NO!!!!!!!!! I have rifled PVC pipe available in 1.5" sch40, 2" sch40, and 2" sch80. THAT'S IT!!! If I was set up to do other sizes of pipe or other materials, (aluminum) I think it stands to reason that I would offer these items for sale on the order form!!!!
Q: I built a spudgun with dual ignition but I can only get one spark...What am i doing wrong?
A: When trying to accomplish dual ignition, the spark gaps MUST BE WIRED IN SERIES!!!! In a series wiring configuration, the spark must jump both gaps to complete the circuit...thus resulting in 2 sparks. If it is wired in parrallel, the spark will follow the path of least resistance and only jump the shortest gap. The diagram below depicts a series wired dual ignition system.
(IGNITOR)------o o-----------o o------(BACK TO IGNITOR)
Q: I can't get my electric sprinkler valve to work.....How do I wire this damn thing?!
A: To obtain 24v (actually 27v) from (3) 9 volt batteries, they must be wired in series. The diagram below depicts the proper way to wire a 24v sprinkler valve.
----(+ -)----(+ -)----(+ -)----[switch]----(valve)----back to first battery connector---
Q: "I want to start a spudgun business and sell potato guns on the internet too. Can you give me some advice on how to go about starting a business like you have"?
A: You have got to be kidding me?!?! I am not the type to discourage anyone from starting their own business. In fact I welcome it...competition is the key to capitalism. But who in their right mind actually thinks that they will get a reply from me to teach them what I know about running a business that would be in direct competition with mine. I like competition but I sure as hell won't help create it or support it. There are other companies out there selling spudguns. The operators of some of these companies are actually good friends of mine....but I don't link to their sites. If you want to run a spudgun business, do the research and figure it out....or scratch together a few hundred thousand dollars and buy me out.
Q: How do I build a potato launcher?
A: Check out the "Build One" page of this site thoroughly, and make sure you see many other sites from my links page. There is a ton of information out there, just waiting for you to find it.
Q: What size barrel should I choose?
A: Any size you want. Typically people use 1.5" or 2" pipe for the barrel, this being that regular potatoes are of this size. It is important that the spud seal all around the barrel surface. Make sure it is not too small however, especially if your chamber is large, or the gas might not be able to get out fast enough.
Q: What should I use for fuel?
A: Hair spray is the "standard" but I personally stay away from hairspray. It gums up the chamber, insulates the electrodes, and glues the end cap on. (get out a big wrench!!) Right guard deoderant(UPDATE:Right Guard no longer uses flamable propellent), static guard, automotive starting fluid (ether), propane, and butane all work very well. DO NOT USE oxy/acetylene or any other high-powered fuels....your spudgun WILL BLOW UP!! Also, never use insect repelant!! It has some pretty nasty stuff in it that will melt the plastic.
Q: How do I build ******* that I see on your site?
A: ...Insert name of item or device or construction for *******. Many of the things on this site are purely for display or educational/intrigue purposes only. Many of them are unique to this site--i.e. I (or Ed, the previous owner) invented them for whatever use I (or he) deemed necessary at the time, and I even sell some of these unique things. If more info isn't given on the site it is for fairly obvious reason. :) Popular examples include my propane meter, modified sprinkler valves, the Supah-valve, custom pneumatic spudguns, and first and foremost the rifled barrels. Many of these things are proprietary secrets so don't even ask....you won't get a reply.
Q: Do you have any plans for ******* that I can get/buy from you?
A: No. I design as I build and re-produce from memory. The only plans/prints I have are the pics you see on the site. I have no blue prints or drawings that can be e-mailed, faxed, or otherwise conveyed to another party.
Q: I E-mailed you a question last week...Why didn't you reply?
Well...there may be several reasons. E-mails are generally low on my priority list. If I am buried with orders...I don't have time to respond to E-mails right away. Paying customers are always at the extreme top of my priority list. Orders come first....period. After that...e-mails are replyed to in order of importance. If you asked me a question that has been addressed in a fair amount of detail somewhere on the site...you will not get a reply. It will simply be deleted and never given a second thought. I did not spend the time putting together a site that is this complete just to spend more time answering questions that have already been answered.
Q: Is there an optimum barrel to chamber volume ratio?
A: See the theory page. There is a section pertaining to this topic found there.
Q: Is PVC or ABS better?
A: They are both fine materials for building a launcher. Keep in mind that ABS is not pressure rated. Your chances of it failing are MUCH higher. More often than not I have heard of availability being an issue, but you should always be able to get PVC at a large hardware store. Be sure to check out my pros and cons in my materials section.
Q: How long should I wait for the glue to cure?
A: AT LEAST 24 Hours!! Proper solvent welding is a must, and the joints should be allowed to fully cure (not dry) before loaded with the dynamic stresses of burning something quickly.
Q: Why won't my ignitor work?
A: It sucks. No, probably not ;) The gap may be too large (if you are using the BBQ plunger type) or the piezo-ceramic material inside it may be fractured. If using a flint ignitor the flint is either expended or you have gotten it too wet with fuel. Don't use a long stem ignitor!
Q: What if it won't fire and there's plenty of fuel in it?
A: That's just it, probably too much fuel. Sometimes you need to wait several seconds for the gas to disperse and mix well with the oxidizer. If you have too much fuel, open the chamber and AIR IT OUT without trying to ignite it. After the gas clears test the ignitor with both ends pointed in safe directions (not at your face). When the ignitor works again, try it again with less fuel. A 1/2 second to 1 second shot of fuel is all you generally need.
Q: Is combustion or pneumatic type better for me?
A: If you are asking you have probably never built one before. A combustion type gun is a great way to start, as it is far easier to build and operate than a pneumatic type. I also stick with combustion type from an efficiency point of view, but I won't go into that here...
Q: Are these things legal?
A: That depends on where you live/wanna shoot spudguns. The Fed's say they are OK as I obtained a letter from them concerning my SP9004. I have heard of several instances where they were 'not legal' but that has usually been due to the operator of such launcher using it in an unacceptable manner (shooting a hole in the neighbors house). Many cities and munincipalities have local ordances pertaining to the use of spudguns inside city limits. Ask someone that would know on the local level.
Q: I just shot a hole in my neighbors house and the cops took it away. What do I do now?
A: Good. If you shot a hole in your neighbors house, you probably shouldn't be playing with a spudgun in the first place. You are the reason that most cities have some sort of ordance against the use of spudguns in the city. Don't look to me for sympathy!!! Hey, keep it fun, play it safe, shoot these things in a safe manner and you should never have to worry about something like that.
document created 7/6/2002 9:44:14 PM;
last modified 3/22/2009 6:36:04 PM