My first BigGun :D

[wyz2285]

Hello everybody
Well I have been planing on building a decent spudgun for about a month ago when I was bored with airsoft guns, but didn´t have time to really think about it, as I had to study for some test.
Finally when I got a week to think about a design. Initially I wanted to build it in full aluminum, as I´m not familiar with combustions and they looks dangerous .
But I just couldn´t find any large-bore aluminum tubes and accessories ,
so I had to use PVC , but I really consider that´s not safe enough. Any way, I finished it and fired it 5 time till now , haven´t get enough courage to fire more times .
specifications:
basic gun design: co-axial.
barrel: 1 metre long 3 cm dia pvc
chamber:about 40 cm long 9 cm dia pvc, prox 1 L volume with chamber fan.
Ignition: 1.5 V continue spark ignition.
fuel: butane(I couldn´t find propane, only butane and MAPP)
I use syrige fuel injection.

[Gaderelguitarist]

Those are the most strange pvc fittings I've ever seen. Be sure to check that they are indeed rated for pressure.

[jackssmirkingrevenge]

Those are the most strange pvc fittings I've ever seen.

Those of us in Europe think the same of your white PVC

Nice job wyz2285 and yay for syringe metering

[wyz2285]

The pvc tube are a self close type, they have a rubber ring in the inside, so i don't have to glue them, only need use few screws to make sure they stays together . Ya the syringe looks like the easiest way to inject fuel to me so i used it

[Labtecpower]

I wouldn't trust the self-sealing types. I have seen them at the local DIY store
(GAMMA!)
a few years ago (when I wanted to make the same type of gun )
They are pretty thin-walled.
Also, do not underestimate the amount of force applied to the caps and screws. A combustion gun generates about 6 bar (kg/cm 2)

There are several vids on youtube with guns of this type exploding.

But: the gun itself looks very good. It looks clean, and well constructed. (apart from the used material )

I'd like to see a gun constructed with proper materials. keep em coming!

[wyz2285]

Can you show me some of there videos ? I have chosen these pvc tubes because a friend of my build one using them and worked out very well.
Anyway I'm still looking for metal tubes so...
And these tubes aren't thin-walled, i think so, the wall has 5 mm, looks strong

[jrrdw]

If you used ' Krylon Fusion' or a 'adhesion promoter' the paint will stick good. If not it will start flaking off.

[Labtecpower]

[youtube][/youtube]

This PVC is about as strong as yours, I think.

[jakethebeast]

i think that was white pvc...

[Labtecpower]

White pvc is exactly the same material as grey pvc (except from the color )

[wyz2285]

Thanks for the video, looks painful
But I saw these two guns on youtube too, one of tem is made of a coke bottle, witch i think it´s worth than my pvc tubes. The other one is using the same type of pvc as I do and looks fine
1 video:
http://www.youtube.com/watch?v=8k2sv1vdUw8
2 video:
http://www.youtube.com/watch?v=biwaOZiNHhk

[Gaderelguitarist]

I've had an end cap blow off like that before. Good thing I wasn't stupid enough to put the ignition source in it though

On paint, I've never had paint "flake" off of cannons before. I use Rustoleum professional enamel spray. It coats well and doesn't come off unless you actively try to remove it.

[motorfixer1]

Nice, clean looking launcher, still made out of plastic though.

[mark.f]

Nice, clean looking launcher, still made out of plastic though.

So is this one. Oh, and this one.

[Gun Freak]

still made out of plastic though.

Whats wrong with plastic?