SpudFiles

Hey I made this mini out of a tylenol bottle the size of a chapstick and noticed the nice flame-colored glow it gave off. Being one with an odd attraction to fire, I wondered if I could use a clearish 12 oz. coke bottle to see all the fun but keep my skin intact. Only tell me it's safe if you've tried it, I don't want a newbie telling me it's all good then having to explain to the doctor why I have plastic shards in my gut.

Here's my current mini; my sparker broke.

Well from my experience, coke bottles and fire don't work mix.
It warps when it gets used, it collapses on itself while shooting, and melt easily.

I've done it. They survive for a few shots and then start to melt. Probably not a good idea. However, I've seen glass champagne bottles used for basic combustions without problems. They hold over 200 psi (according to a site I saw).

Peace,
Pete Zaria.

I saw a gun with an A1 steak sauce bottle chamber.Why not use clear pvc?

if you put a big bottle(1.25L) in the oven, it will shrink and become a bit thicker and harder. that might help! and i have heard that bottles burst at 150 psi, if you worried about pressures!

Hm sounds a little risky. Thanks for saving my skin by the way. I've heard of people using shampoo bottles, is that safe?

Shampoo bottles are pretty thick, wouldent recomend it though.

why don't you get the real stuff!

Heating PET to shrink it is not a good idea, the plastic becomes brittle quite easily.
I've changed chambers many times, but the latest one on my coke-bottle combustion gun has fired thousands of shots and shows no signs of heat damage. It won't withstand a high rate of fire, but for regular use it's more than adequate.

Thats a really sweet set up. You're use of ignition I find interesting...no doubt it's a good way to ignite and you've set it up well, but I alway found it too much work for what I reckon is a simple stage of construction.

Good work... How far does it shoot by the way?

KIR

80-100 m with the old barrel, it was recently upgraded with a 2m barrel.
I've had electronics for a hobby since long before I got into spudguns, so making a flyback circuit is no big deal. I had all the parts lying around for this one.
Soda bottles are designed to handle pressure, get the thick walled ones if you can since they will handle the heat better as well. The electrodes for the spark gap are best connected through the thick bottom.

Isn't that a glass bottle?

yes pete bottles are perfectly safe i have used 16.9 oz and 2liters but i dont think heat shrinking is a good idea its true that they become brittle.
you will want to keep the inside clean from resadue from areosols or it will cause them to melt.(just make sure not to spray too much in) and with the rough tests i did on pressure the 16.9 start brusting at 110 and the 2 liters at around 150. and there will always be exeptions for a faulty bottle. i used duck tape and wrappped some pete bottles and it increased the amount of pressure it held .....im starting to ramble anyway i say yes they are safe for combustion use

Tyro wrote:why don't you get the real stuff!

I have the real stuff, but the sparker's messing up, so I'm doing a mini-project with a weaker sparker I have laying around until I can get a disposable camera

GalFisk wrote:80-100 m with the old barrel, it was recently upgraded with a 2m barrel.
I've had electronics for a hobby since long before I got into spudguns, so making a flyback circuit is no big deal. I had all the parts lying around for this one.
Soda bottles are designed to handle pressure, get the thick walled ones if you can since they will handle the heat better as well. The electrodes for the spark gap are best connected through the thick bottom.

I dunno what it is, but I really think you have a cool gun:D I wish I was good at electronics...that's not really my strong point. Anyway sorry to be off topic.

With soda bottles, depending on which ones, but here in a Australia the bottle I used lid kept fyling off. I made a deatchable barrel (which was extremely tedious) to spray the fuel in but I could never get fuel close enough to the sparkers. Not wanting to reposition my ignition screws I just tape the lid whenever I use it, which isn't that often.

KIR