SpudFiles

Hi all BTW im from england!!, I have decided to build a hybrid and was wondering what chamber material I should use. I can't find a SCBA tank for any reasonable money, not sure if I have access to any Black iron fittings but I would like it to be a rather large chamber, something like 4" hence the SCBA idea. What do you guys think about using a large CO2 fire extinguisher? have 2 holes tapped into it, one for the metered fuel using a remote metering system on a 1/4" tee also connecting the air supply and the other for the spark plug. what X mix do you think that the extinguisher could handle? and how to attach the union or cam lock fitting to the front?

All ideas welcome Dave

a 4" chamber will create a beast of a cannon


http://www.bes.co.uk/

or http://www.kiowa.com/

these the both have malleable iron and stainless fittings (kiowa)

An old CO₂ tank should be completely fine for anything below 10x, and probably quite a bit higher than that. Personally, I'd have fittings welded rather than holes tapped, as there may not be thick enough material to get a good grip with bigger threads.

Thank you for your help. DYI I have thought about this problem all of the time that I was out lamping and it has just dawned on me that I can easily get hold of paintball CO2 tanks what do you think? Im guessing that they will have thicker walls which would make a stronger thread but the only problem is that I have now dramatically reduced the chamber volume. Maybe I should just get the best of both worlds and look out for a SCBA tank:P As for the holes that have to be tapped, Obviously I need atleast 2, one for the spark and another for fuel/air, what metering/air setup would you suggest? I though about tapping a hole for 1/4" ball valve going to a female quick connect. Then build a detatchable meter that attaches to the female quick connect to fuel then take it off, attach the compressor and charge the cannon.


What do you guys think?

Just go to a local welding shop, find a few feet of scrap 4" steel pipe lying around, and ask how much it would cost you to get it. I'm betting less than $40 in most cases, for a reasonably sized piece. If you're lucky like I was, you could even find some SCH 80, although that isn't really necessary.

I would suggest a manometric metering system, as they are, by nature, universal, easily upgradeable, and don't require as much much math to figure out.

Yes I agree that getting steel pipe would be the best idea but because this is my first hybrid and I rekon it would be better for me to learn a bit more about them with one made from a paintball tank than a HUGE steel pipe. what x mix of air/propane would I safely get from a CO2 paintball tank? thanks dave

Safely, 15 - 20x. Possibly quite a bit more, depending on the tank's construction.

That sounds great!! Paintball tank hybrid it is then:) What do you think about tapping the hole for the fueling into the bottom(flat part) and the hole for the spark plug into the side? also any ideas on how to attach a barrel? Thanks Dave

Hello all,

First ever post at spudfiles.com. Just wanted to say that I have a similar project I am working on (hybrid with a CO2 combustion tank).

Dave_424, how will you power your spark plug? I haven't figured out how to do this on a mobile model, but I would like to get away from pizo-electric igniters (bad results in the past). How do you get the 20kv to jump the gap?

~fogus

Fogus, how about a stun gun? You can get some acclaimed 100KV ones off eBay for around $20 shipped. Nice juicy spark for a reasonable price.

pimpmann22 wrote:Fogus, how about a stun gun? You can get some acclaimed 100KV ones off eBay for around $20 shipped. Nice juicy spark for a reasonable price.

I am in Canada and they are banned I believe. Any ideas? Can I make it?

I can buy a semi auto .45 handgun, but no non-lethal stun gun.

You actually can use a BBQ igniter, but you'll need a very small gap (<1mm) if you want to use higher mixes. As for getting a stungun in canada, I'd recommend getting a "high voltage circuit" from BCarms (there's a blue link near the top left of the page). I think they're around [edit:] $25).

_Fnord wrote:You actually can use a BBQ igniter, but you'll need a very small gap (<1mm) if you want to use higher mixes. As for getting a stungun in canada, I'd recommend getting a "high voltage circuit" from BCarms (there's a blue link near the top left of the page). I think they're around [edit:] $25).

Awsome, thanks Fnord. Does anyone have experience on these things crossing the USA/Can border?

BC says they can go to Canada just fine. Was the reason they were converted to "high voltage circuits" to begin with.