SpudFiles

Here is a small gun I made last week. I thought I was being original by making a spark gap for ignition, and for bending he chamber down around the bottom of the barrel, but after finding this site I see that I just did a poor job of reinventing the wheel.

The barrel is 38" x 1.25" and the chamber is 12" x 2" plus the bend. It's solid core PVC, sealed and reinforced with #8 x 1/2" wood screws, with a gloss black paintjob. The ignition is a piezo from a fireplace lighter, keeping the original triger, and has a 3/16" spark gap. The fuel is canned butane.

Now tear it up for me so I can improve on my next one.

Edit: dimension typos

Great work for the first cannon.
Try a Pneumatic next, theyre harder, but stronger. The gun might be solid core PVC, but I dont think some of the fittings are solid. DWV (Non-pressure rated) pipe and pressure PVC pipe look different. I think someone else might tell ya.
DWV is fine for a combustion, but don't use it for anything other than a simple combustion cannon.

Looks pretty decent to me, and cleanly built. I assume you've painted it?

- On a more powerful cannon, those elbows and reducers wouldn't be up to spec, but here, they should be fine.
- The chamber's size is about right for a metered fuel, but for a spray fuel, it may be on the slightly small size for the barrel.

And heck, half of what we do here is badly reinvent the wheel. Not literally, that would of course be stupid... "I know, let's make it a Reuleaux triangle instead!"

Nice done for a first cannon, especially the muzzle detail. You forgot the all-important damage pics though

What? No mashed potato pics? If your going to reinvent everything, don't leave the damage pics out!

Welcome to Spudfiles.

Edit: Dam Jack, got me by a minute......

Great gun! Hey, if your comparing your gun to the great stuff on this site you're being extraordinarily hard on yourself. That's like taking your first steps as a toddler and beating yourself up because you can't do gymnastics.

Things you did well: Trigger, handle, solid core PVC coming up with a great ignition source with your own brain regardless of whether it's already been done, over/under design for shorter length and easier handling, support structure to stablize the barrel, and nice serrated barrel for cutting potatoes - one of the best I've seen!

Things I think you can improve: Larger chamber size to allow for metered propane, metered propane, increase the number of spark gaps, tap your holes on double thick walls rather than the thinner wall (with the exception of using lots of epoxy to reinforce the hole), larger barrel, chamber fan.

Really for your first post on this site this is very good!

I agree with the rest, pretty decent cannon here. I like it a lot actually...nice and compact, light carrying. I don't see how or where you're getting fresh air in your chamber and injecting your fuel.

Your potato cutter (I assume that's what that is) looks really cool and different although I'm not sure it will perform any better than just a standard blade sharpened onto the barrel muzzle.

Radiation wrote:Things I think you can improve: Larger chamber size to allow for metered propane, metered propane, increase the number of spark gaps, tap your holes on double thick walls rather than the thinner wall (with the exception of using lots of epoxy to reinforce the hole), larger barrel, chamber fan.

So basically your telling him to make it a bigger gun and use metered propane...

You did a great job mate, especially for your first. I can see that you will go along way in these forums and your now addictive hobby. Not to mention be great pals with Starman lol.

Nice work.

Thanks. I'm surprised it wasn't immediately ripped to shreds here. I have the parts to put a 3" id chamber on my next gun, but this uses 2" because that's what I had on hand. If I didn't have the parts already, I wouldn't have thought to make this, and I never would have found this site.

The beveled muzzle is to help cut the potato. I just made the small bevels, as apposed to a single bevel around the circumferance, for appearance. The supports are poplar. There is a 1/16" hole for butane spray, and the end cap isn't epoxied to the chamber. It has a tight fitting, 3" bolt/pin fastener for semi quick access to the chamber. I went today after seeing some of the designs on this site and bought a 2" to 1" reducer and a 1" ball valve to upgrade this.

I can't believe some of the potato guns the members here have made. I always thought most potato cannons were 6' sections of PVC with an endcap and a hole to ignite it with a lighter.

Carlman wrote: Not to mention be great pals with Starman lol.

Hey hey now, I resemble that remark...

PythonWallace wrote:Thanks. I'm surprised it wasn't immediately ripped to shreds here.

Nah it's pretty rare really, especially if you make an effort to communicate your ideas or questions in a reasonable way. You had some decent pictures, presented some critical detail and wrote in complete sentences and paragraphs....a decent sense of humor. You made real effort and it shows.

Its tough to beat the portability and convenience of a solid combustion. As far as spray and pray guns go, this is pretty slick.

You sound like you have browsed this site a bit, so you know there is a LOT more you can do with this hobby. For a "first gun post", it sounds like there is a lot of interest here, I cant wait to see what else you can create.

Python, you did the exact same thing I did after posting my gun for the first time and getting all kinds if suggestions, I ran out and bought more stuff. the addiction begins! I can't wait to see what you do next!

great cannon id just add a chamber fan

nibbler125 wrote:great cannon id just add a chamber fan

I already have a fan with a momentary push button switch and an 8x AA battery pack hooked up in the 3" chamber for my next gun. I also have an old 100,000v stun gun I'm going to dig up for my ignition source. About that, do you normally use the trigger on the stun gun, because I was thinkin about using a momentary switch trigger wired to the batterys in it, and gluing the actual triger down so it's always on. I have a 2hp air compressor for airbrushing, so I'm thinking about tryin a pnumatic design, but I'm laid off so I can't do anything that costs any money right now.

Just replace the momentary switch for the fan with a plain on/off switch. You'll want to run the fan for A) mixing air and fuel, B) during ignition..improves performance noticably, C) to assist in expelling spent gases after firing.

So basically you need to just keep it running most of the time while you're firing. This is why I am a proponent configuring a little beefier battery/power supply setup in the cannon.

I just used rubber bands to pin the stun gun's trigger down while switching power to it externally for firing. See the trip thunder ignition from the sig link below.