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There's no reason why a 3/4" burst disk hybrid would cost much more than a pneumatic version.
Let me make my stance clear: a lot of users on this forum are teens and students. Often they have parents who are sceptical of what they do and are not keen on them spending lots of money. Stepping from ...

It seems that the reason so few people build hybrids is because the typical gains in power are often outweighed by a) the greater financial costs, b) the greater hassle in reloading, and c) the more time and planning involved.

Whilst hybrids are definitely fun, it seems a daunting area for many ...

The first design is liable to break quite easily and seems overcomplicated. The second design should work, although the main concern is exhaust valve throughput (1/4 of an inch may not have the flowrate to vent the pilot almost instantly).

Also, think about how you will service your piston if it ...

Nice job on the cannon, looks like it'll put a golf ball 200 yards easy.
At 50 psi it puts a lemon about 150 metres (165 yards), although I haven't tried higher pressures yet.

[youtube]http://www.youtube.com/watch?v=ZwM9vcD-SjY[/youtube]
This is a video testing a frozen lemon into chipboard at 50 ...

Wow! Really clean first, congrats!

I do think you should reduce the pilot volume by replacing the male adapter+cap with a threaded bushing. You should be able to improve performance that way and you could fit a more comfortable pilot valve as well

Thanks :)

Actually I have filled up all of that ...

This is my first cannon showcasing post on SpudFiles, although I have made other cannons in the past. This is also my first piston valve cannon, and is built around a 2" (50mm) tee.

Here are the specs:
- 50cm long 50mm SCH40 PVC chamber (giving for a 1 litre chamber approx.)
- Piston built from ...

Hmmm, I looked there and didn't see anything this small... Maybe my Bunnings is poorly stocked, but I'll look again next time I'm there.

For a few years I have been living in France where it is easy to get components, however upon moving to Oz I am facing no end of problems.

My latest problem is finding the fitting many people use to attach a torch head to a standard thread, described as 1/4" compression to 1/4" NPT.

http://www ...

I called up the Stepney branch today and the guy quoted $10/m for 65mm class 12, and $35/m for 80mm class 12. Considering the relatively low cost of 65mm could I build the whole thing out of it?

Imagine if the chamber were 0.7 metres long and 65mm diam; would the gas be able to mix in a long and ...

MrCrowley wrote:Yup, they should do. Reece's stock everything up to 110mm pressure rated PVC where I live, including 65mm and 80mm diameters.

Are they reasonably priced? I am on a bit of a budget.

Crna Legija wrote:I would if a round jams your stuffed.

Yeah I agree, and now I know where to buy SCH40. Plus, I found a source for cheap tennis balls

CDHraider, in your photo I think I can make out a small compression fitting attached on to the propane head? I am thinking of using this design - does it work well for you?

we ordered some 225mm pn18 pipe at work.
Sounds good, looks messy :) I'll go for an 80mm-100mm chamber though :wink:

There is a small amount of medium strength threadlocker on the threads, but I've removed at least half a dozen of them and didn't have any problems.
This idea is attractive as it ...

Looked at all those sites, they're all stupidly priced.. I will stick to eBay for now. Might order a regulator tomorrow and try and sort out what PVC I need.

Out of curiosity do Reece's stock big pressure rated PVC (80mm+)? I am eyeing up something like that for a chamber, so I can put in a decent ...

Crna Legija wrote:where in ozland are you? I'm in Melbourne

Adelaide, so even less supply for stuff. Any tips on where you have bought bits and pieces?

PS we should probably start an Aussie discussion/reference thread, we have drifted from the title