Mini steam gun

[DYI]

This is the miniature version of a MUCH larger steam cannon that I am building, and is my second working pneumatic. I built it to try and determine if it is worth proceding with the big version and have been fairly pleased with the results, although there is only so much power that one can squeeze out of a 1.7 cubic inch chamber.

STATS: Chamber- 6" by 1/2" galvanised steel pipe nipple
Barrel - 6" by 1/4" galvanised steel pipe nipple
Boiler -6" by 1-1/4" galvanised steel pipe nipple
Valve- 1/2" ball valve actuated by...my arm. It's only really a proof of concept, and you can imagine trying to design a piston valve to withstand 300 degrees fahrenheit. According to my camera, I open the valve fully in ~50 ms, but I somehow doubt that. The faster opening times could be due to the fact that the gun is held in the vise, and the valve is opened by pulling a wire that is attached into the handle.

Damage- @110 psi, it can drive a spiral nail 3/8" into plywood, and fire a single airsoft BB (.12 gram) through more than 1-1/2" of styrofoam, which tells me that its moving pretty f***ing fast, since my 300fps airsoft rifle can't even make it 1/4 of the way through.

Misc.- The boiler takes at least 30 minutes of heating to get to a decent pressure, and I can get quite a few shots by using steam from the boiler to fill the chamber. I don't really know what the max number of shots is, because I don't want to run out of water and have a possibly exploding boiler on my hands( about the equivalent of DDT in a hybrid). I ran into that problem when I tried using steam in my first pneumatic. It's pretty scary when the gauge suddenly starts rising at 20psi/second for no apparent reason.

Anyhow, enough with the rambling, and on with the pictures (and a video)
[youtube][/youtube]

[mike1010]

sweet i like it but doesnt the pressure gauge get too hot from all that heat

[bob-a-lu]

put your hand in front of that and see what happens youll end up like those guys from the starburst commercial

[DYI]

The temp only goes up to about 300 F, and if the gauge does break, I don't really care, since it only cost $3. A coiled pipe from mcmaster would be the way to protect it, but I've had some bad experiences with them. I've fired multiple times and the gauge is still fine, even though it is not ment for being used with steam.
EDIT: If I put my hand in front of it I wouldn't have any hand left. Steam burns are horrible.

[Pyro Ninja]

Holy hell that was a big blast of steam.....that was cool
good job

[DYI]

That "blast" was only at 55 psi, with an almost empty boiler. You should see it at 110.

[Fnord]

Wow, that was cool.[hot]
I think I'm going to try this sometime.
Maybe I'll make a portable one with an alcohol stove for heat.
Something to think about, would that be classified as a pneumatic or combustion? I mean, you're using the energy from combustion to compress gas. I guess it's technically a hybrid:)

[MrCrowley]

You should of used copper instead of galv steel, it would conduct the heat alot faster. But another then that, that is a nice cannon.

[origin unknown]

Make a longer barrel for it to harness all that energy I saw coming out of it!

[potatoflinger]

That's pretty amazing

[Infernal Maveric]

That looks like a heck of a lot of fun there. Like Origin Unknow said, you should make a 1m or 2m barrel for that thing. Seems like a waste to have a tiny barrel for a really powerful cannon, even if it is a proof of concept.

Can't wait to see the larger version of this.

[shud_b_rite]

Wicked. Yea it looks like you should have either a bigger valve or longer barrel because that is a heck of a lot of steam. Nice work. It must suck how it takes 30 minutes to boil.

[DYI]

The shot that I showed a video of wasn't a normal shot, it was the boiler venting. The boiler is the large piece at the back of the gun. The actual chamber is only 1/2"x6", the boiler is only used to fill that chamber. But yes, the barrel should be at least twice as long as it is. The only reason for the short barrel was the poorly supplied hardware stores in my area, it was the longest piece of 1/4" in any material that I could obtain.
MrCrowley: The only reason that it is steel is that an equivalent amount of copper would cost at least two times as much, and would have to be silver soldered or brazed so that the joints wouldn't fail, neither of which I have the tools to do.
IM: You're going to have to wait a while to see the larger version, as I'm running low on funds right now. Maybe in a few months.
EDIT: Just made video of actual firing (original was boiler venting)
[youtube][/youtube]