Potato Guns

[Dr_Evil]

I finally got mine going again after purchasing some ignition upgrade stuff a month or two ago. I finally found a switch that works a few days ago. Time will tell how long it will last. Right now I am using a single 18650 to power a spark gap ignitor. I'd like to find something else though since there really isn't a way to prevent the voltage from dropping to low. I would need something capable of handling 3.5 to 5v with a 3 amp draw.

There is one issue I am having though. The electrodes keep getting dirty which prevents it from sparking. I have two screws 180 directly opposite of each other with a gap of about 1/8". What I've been using for fuel is static guard. I want something clean(er) that won't blow the cannon up. The report is one thing I like about using static guard. Hopefully I can find something clean(er) with the same report.

I'll post pictures and a video later. It's a pretty simple setup. A 30" long barrel with a 2" inner diameter. The chamber is about 22" long with a 4" inner diameter and a screw on cap. The material is PVC.

 

[RawPaul]

I've heard/seen online of people using a stun gun for an ignition source. You attach/solder wires to the tips and then tie them onto 2 sheet metal screws which go inside the chamber. Can't remember how far apart they were but I'm sure you could google it. You would have the switch and everything right there and just plug it into the wall to recharge the batts.

 

[TheDukeAnumber1]

The most reliable ignition source I have ever used is lantern lighters, those things don't care how dirty they are. My recommendation for a clean fuel is mapp gas, you can buy it at home improvement stores in small yellow canisters. It burns a lot hotter than propane and I've used it for a while and had no problems.

 

[Dr_Evil]

How much do you put in? I have no way of putting any in unless I use the torch I have without igniting the fuel.

 

[Alaskan]

What, you must have a wide gap? A regular spark plug won't do it well enough?

 

[Dr_Evil]

The approximate gap is listed a few posts above. As for a spark plug, that would have required a bit more work and materials.

 

[vortish]

the best ignition thing I found for spud cannons are from propane grills. those little push button ignitors are the best! you can get them at a sears or similar store for about fifteen bucks or less. best fuel for spud cannons are hair spray, butane, any aerosol that come with a flame warning. brake cleaner or starting fluid for diesels work the best I found. I have one that i shot tennis balls over two hundred yards with starting fluid. just make sure your chamber is 100 % larger than the bore of the cannon. use two to three second squirts and you be fine

 

[Dr_Evil]

the best ignition thing I found for spud cannons are from propane grills. those little push button ignitors are the best!

I just modded mine because I hated those things. My new setup keeps sparking as long as I hold the switch down and the electrodes, which are screws, aren't gummed up by crappy fuels. That's why I need something cleaner that won't cause the cannon to blow up.

 

[vortish]

ether starting fluid its basically just aerosol alcohol

 

[Down with Umbrella]

Oooo a potato cannon thread? Awesome! I've used the red BBQ lighters and you didn't work well for me. However. I know people who have had great luck with disassembling those cheap tasers you can buy at the mall then Incorporate them into the chamber.

I elected to use CO2 (sorry for the size I'll have to edit that)

 

[AUTO XX]

I made mine with a PVC insert for golf balls.
A bit of graphite spray keeps your balls from sticking (especially in hot weather, no one likes to batwing ) and they will travel about 900 yards.
The PVC pipe is fastened with the same anchor pin within the ABS that keeps the spud from dropping into the firing chamber and the ABS reinforces it so it doesn't blow up.

I use nail polish DRYING spray as a propellant. It is full of "enes" and "anes" but it also has vitamin E to keep your threads from sticking like hairspray will cause, plus it smells nice

My ignition is a 3 point, 26,000v spark with 3/16" gaps. The triple pop makes all of your fuel ignite at the same time so you don't get the ring of fire in front of your barrel and the fuel is used completely on the projectile.

The streamwatch girls would always bug the old fish and wildlife officers to come check on me so they could shoot the spud gun, throw hatchets (we made a "golf" course) and hang out at the cabin I was building. The fish and wildlife officers were even shooting at ravens with the spud gun...

A bear came into camp and got a spud surprise, it hit him right in the nose and bowled him over backward. You could see the pads of all 4 of his paws in the video ^_^ I had the shotgun as a backup but didn't want to kill him (he was bluff charging to 6' away so pretty aggressive) I have the video on my facebook but lost the original file in a HDD crash. After getting shot with a spud he ran into the nearly finished outhouse and chewed on the toilet seat.

 

[Dr_Evil]

I just figured out what the problem is in mine. My electrodes aren't getting dirty to the point of preventing ignition. Pictures will be coming shortly.

This is what's going on after one or two shots. Instead of jumping the gap, the spark makes it's way through the moisture coating the inside. It's similar to what happens to a CD in the microwave. The cannon works fine again after I wipe the area around the electrodes down with a dry cloth. Now I need to figure out a way to prevent that.

 

[Ehgemus]

I made at least 10 of these back in the day. This is the last one I made and my kids really like it.
Best ammo is walnuts, you can shot them through plywood. Empty calking tubes are pretty fun to.

I need to build me one of these. http://youtu.be/T2exjMnHzhM

 

[The Lightning Stalker]

Wow guys, my site is finally back up. There is some
useful information there relating to combustion cannons.

Main Page
Propane Cannon
Ignition Coil Driver

 

[Dr_Evil]