Here Steve is presenting our first prototype. We are waiting for the glue to dry thoroughly before we test fired it. After some time we put about 20 p.s.i. in it and test fired it. This cannon consists of a total of about 971 cu.in. of chamber, a 72" x 2" smooth bore barrel, pressure gauge, compressed air hose male chuck, and 2" ball valve. We fired it by smacking the 2" ball valve's paddle with a large rubber mallet. Steve says, that was the "old days." I knew I had to come up with another way to open the valve. Smacking around pressurized SCH 40 PVC with a rubber mallet isn't particularly safe - or smart!

Hey... I just noticed my '67 Ford in this picture... it's sweet!

Here is a look at the cannon from the ouchie-zone. Note the taper on the barrel - belt sanders are gnarly machines and can put a nice tater-cutter on just about anything.

Here is the same cannon with a fresh coat of paint. The barrel has been fitted with a 2" SCH 40 PVC "T" with the T section having a 2.25" ID whole cut in it so the projectile can exit the ouchie-zone without a problem. We noticed that the T changed the resonance of the barrel some. When the cannon is well charged and fired it reports with a sharp high-pitched CRACK! It sounds great - and looks cool too I think. BTW: The taper is gone now. We found taters a bit anticlimactic at 110 p.s.i. - they just vaporized in a puff of tater-dust.

We also replaced the male compressor fitting with a female quick-release type. That alone was a nice change.

Here is a close-up on the operational end of the cannon. Steve just had to have a pressure gauge on it. Even though the compressor's regulator could be set to prevent over-charging the cannon I put one on anyway. Ended up liking it too... very handy. Also fitted it with a schrader valve. The schrader works, but it takes quite a while to charge through it.

Here is a right-rear 3/4 view of the cannon. Not much else to say about it here.

Steve, with his smooth bore mini-spudinator. Spare parts and some glue and ta-da... another spud launcher. I must admit though, this thing is useless for spud... great for just about anything else with a 1/2" diameter. We have launched metal rods, wooden dowels, car antennas (an exceptionally good flyer), metal slugs, golf tees, pebbles, fishing sinkers/weights, home-made darts (coat hanger and small pieces of plastic bags for flights), and nails. Oh yeah... nails. We stuck a little piece of plastic bag on a nail, then shoved a piece of rubber hose down over the head to take up barrel room. We fired that at a piece of 1/2" plywood with about 80 p.s.i. It went all the way through the board and up about one half of the nail. It might have completely sank it, but the nail bent over.

Here is a close-up of the little cannon. Notice the little bump near the forward reducer. While attempting to tap threads, the gauge would not seal so we puckied up a nut and bolt and put that through the whole. Then we put liquid steel over the bolt head to seal it and make it a bit better looking. This little cannon is complete with schrader, gauge, and female quick disconnect for chamber charging. BTW: That's a 3/4" PVC valve. Steve is getting quite good at snapping it open. He is working on a set of plans for his next cannon. It looks to be v-e-r-y interesting.

Here is another look at the larger cannon. This picture shows it fitted with another one of its barrels. We have six so far. This one is a 3" x 36" - terrible for aim, but nice report. The other barrels are: 3/4" x 84", 1" x 84", 1.25" x 84, 1.5" x 84", and 2" x 72". I was inspired by Joel's Mega-Launcher to build this barrel. I am not getting the performance of his machine, but this one can launch a 20 oz. bottle quite well!

I suspect many of you get the same feeling as I... something else must be tweaked, modded, repainted, et cetera. As you can see that little bug bit me too. The cannon was not rebuilt, but was repainted and fitted with a pneumatic ram to quickly open the 2" PVC ball valve. Beating on this valve when the chambers are charged is not a good idea, and I didn't want to use a modified sprinkler valve, or 3/4" exhaust valves either. So... I came up with a piston actuator for the valve. The piston is operating by dumping about 43 cu. in. of 20 p.s.i. compressed air into the closed end. This activity is started by operating a 3/4" sprinkler valve through its electronic solenoid. The pneumatic ram opens the valve in under 90 mS - measured. Check out the picture below for a look at how the piston was fabricated.

Yet another, but here you can get a good look at the pneumatic ram and how it is connected to the ball valve. Note the reinforcement on the valves paddles. The steel also allows for a method to connect the ram's push rod to the valve.

The black pieces that cradle the chambers is made out of 2" x 6" lumber. All of them are clamped down with 7" hose clamps torqued to about 10 in. lbs.

If you make a valve actuator like this be extremely cautious around it when it is triggered. It can smash fingers, break your wrist, or in the least give you a really bad charlie horse.

Here is a direct left side view of the larger cannon. The overall length is 80". The cheesy piece of wood holding up the barrel is getting replaced tomorrow (16 Aug 03).

Left-rear 3/4 view.

Go Back

The Pneumatic Ram

Air entering the 3/4" (green) threaded fitting applies force against the head of the piston (gray) which pushes the piston to the right. The Max-push Air Dump Opening helps prevent over extending the push rod and turn-buckle. This does two things. One, it prevents the piston assembly from cracking/breaking the end cap (teal) and , two) it prevents the actuator from trying to turn the ball valve too far. The Return Pressure Release allows air to escape when resetting the launcher.

WARNING: If you want to implement a pneumatic ram in your ball valve air cannon project take heed to the following information. Pneumatic rams can exert significant and nearly instantaneus force throughout its range of operation. Of course this is dependant on applied air pressure; however, be extremely careful. With pressures as low as 20 P.S.I. a ram such as this can break body parts. Also the 1/2 Max-Push Air Dump Opening is extremely important. It dumps all the air quickly to prevent over-extending the ram, breaking the rear of the ram or the ball valve handle.

Here is a picture of SpudChucker1 with its latest mod - a pressure regulator for the pneumatic actuator. My son and I tested it and it works great! We are very pleased with the results of this modification. Note the copper tubing connections to the main chambers, then to the regulator, then off to the secondary tank.

This picture shows SpudChucker1 with its 3" barrel attached.

This is a close-up of the regulator. We have it set to 20 p.s.i. It seems to work very well at this pressure.

SAFETY WARNING! Always assume the barrel contains a projectile; e.g., ensure the barrel is empty when conducting test fires in an enclosed building. Trust me on that one! Automobile damage can result... not to mention damage to more important things as well - like yourself or others.

This picture is similar to the one above - just a bit wider.

I noticed there were no close-ups of the ball valve setup above... so here's one for you. The steel that has been attached to the ball-valve paddles was fabricated through the application of a lot of heat with generous amounts of vice-grip clampage, and a few good smacks with a heavy hammer for good measure.

This is a picture of SpudChucker1 during a test fire using water and Steve as the projectiles. Normally we launch spuds at 80 to 90 p.s.i. , but with Steve's added weight we had to boost the pressure up a bit to 145 p.s.i. SpudChucker1 is being remotely fired by me.

Steve said afterwards, "What a blast. That was kewl, but the sudden deceleration sucked!"

This is a picture of SpudChucker1 during a test fire using only water and 80 p.s.i. Steve is at the trigger.