rethinking the air cannon

[Steven Pickles]

just thinking out loud...

the air cannon is somewhere amongst the rubble that was once the corridor next to format. when we get it back i'm thinking of decommissioning it.

well, what i'm actually thinking of doing is finding a way to connect up the electrical (not-really-for-air) valves and the turrets directly to our compressor. that way, we can stop using the (silently terrifying) PVC pipe as a pressure vessel, and use the air compressor instead.

not sure if we will get enough throughput from the outlet of the compressor, but let's find out...

http://compressedair.squarespace.com/journal/2012/2/27/can-i-use-pvc-for-my-compressed-air-system.html

... of course, doing this will compress all of the failure points into whatever arrangement we come up with for connecting the valve to the compressor. i might make sense to buy an appropriate valve instead.

pix

[Kim Hawtin]

hi pix,

On Tue, Nov 13, 2012 at 12:40 PM, Steven Pickles <thatp...@gmail.com> wrote:
> just thinking out loud...
8<

> ... of course, doing this will compress all of the failure points into
> whatever arrangement we come up with for connecting the valve to the
> compressor. i might make sense to buy an appropriate valve instead.

what is the flow rate of your air compressor?
usually in cubic feet per minute (CFM).
i've also seen liters per second.
although not sure whats the most common.

so, what is the flow rate you need to launch ... things?

is there any compressed air storage in the current setup?

cheers,

kim
--
"Art without engineering is dreaming; engineering without art is
calculating." --SKR

[Steven Pickles]

On 13 November 2012 13:13, Kim Hawtin <kimh...@gmail.com> wrote:

hi pix,

On Tue, Nov 13, 2012 at 12:40 PM, Steven Pickles <thatp...@gmail.com> wrote:
> just thinking out loud...
8<

meep meep ?

 

> ... of course, doing this will compress all of the failure points into
> whatever arrangement we come up with for connecting the valve to the
> compressor. i might make sense to buy an appropriate valve instead.

what is the flow rate of your air compressor?
usually in cubic feet per minute (CFM).
i've also seen liters per second.
although not sure whats the most common.

i kind of doubt that such figures are quoted in the manual of the one we got from bunnings but i'll have a look... however:

 

so, what is the flow rate you need to launch ... things?

no idea. and surely you realise that it would be much more fun to test than do all this thinkin' :) 

 

is there any compressed air storage in the current setup?

yep, two big PVC tubes (rated to 150psi for water, not gas - hence silently terrifying), with wide ~1" openings for high flow. 

pix

[Fee Plumley]

you say decommissioning ... can't you keep it (or something like it) for Mini Maker Faire?!

and please video any tests or reversioning experiments ;P

--
You received this message because you are subscribed to the Google Groups "HackerSpace - Adelaide, South Australia" group.
To post to this group, send email to hackerspac...@googlegroups.com.
To unsubscribe from this group, send email to hackerspace-adel...@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/hackerspace-adelaide?hl=en.

--

Fee Plumley

>> CROWDFUNDING SUCCESSFUL! reallybigroadtrip can get a bus! <<

Digital Nomad at http://reallybigroadtrip.com - making & sharing geek arts across Australia.

Head Geek at http://technoevangelist.net - spreading the word of geek since 1996.

Chat via twitter, facebook or sign up to my newsletter.

[Steven Pickles]

Hmm, you do make a good point Fee. Perhaps I should just relocate the Force Petal v1.0 to my place for safe keeping, and we can work on a safer (and less unwieldy and enormous) v2.0.

pix

[Ken]

Would it be feasible to charge the PVC pipe from a 12v electric car-tyre pump?
It'd be slow, but does that matter?

[Robert Hart]

Sorry haven't read the rest of the thread,

Not that I've built such a thing, although I've often liked the idea of a large vortex cannon.  So one of the PVC pipes is the receiver tank and the other the cannon?

So is it mostly all about the storage capacity of the receiver tank and the port size of the solenoid valve and how quickly it can release the stored air.  So the compressor actually would not have to be that large so long as it can reach the the total psi  you want to charge the receiver tank with  (150psi can be reached with a small electric tyre pump), then the CFM you choose will only depend on how quickly you want to recharge the receiver tank.

Robert 

[Steven Pickles]

Umm, I'm not sure what this would achieve as we already have a quite massive air compressor and it would still rely on dangerous PVC pressure vessel for compressed air, which I'm trying to eliminate, but yes, technically possible if the car pump can get up to sufficient PSI. 

The plan is to use the pressure vessel in the air compressor we have, and see if it can dump its load of air fast enough to launch something (I'm starting to think the answer to that is no).

pix

[Steven Pickles]

Hey Robert, what you describe is what we already have.

Air compressor (with large currently underutilised air tank) -> PVC pressure vessel -(wide mouth)-> solenoid valve -(wide mouth)-> PVC turret

I'm basically wondering if we can get sufficient flow out of the tank built in to the air compressor to eliminate the need for the (dangerous) PVC pressure vessel.

pix

[Robert Hart]

I've heard  people using a spent CO2 fire extinguisher bottle as a pressure vessel as they are rated for a specific psi and are built to withstand a bit of ruff treatment and best of all have a standard 1/2" tread on them for for air-hoses.

I have few bits and bobs of pneumatic gear let me know if there is something you need, happy to donate. 

Robert

[Steven Pickles]

Yeah I was thinking that might be an option if we can't get enough flow out of the tank on the compressor. Though once the appropriate fittings are used I'm not really sure how much larger the opening on the extinguisher tank will be.

pix

[Kim Hawtin]

hi pix,

On Tue, Nov 13, 2012 at 2:26 PM, Steven Pickles <thatp...@gmail.com> wrote:
> I'm basically wondering if we can get sufficient flow out of the tank built
> in to the air compressor to eliminate the need for the (dangerous) PVC
> pressure vessel.

if you have a dump valve from the ouput of the aircompressor and
storage tank, then you are going to hit that 120-150PSI.

Dumping that directly into a 2" pvc launch tube is going to be enough.
especially if the launched item seals well enough or you have
something that seals behind it. launch tube doesn't have to be too
long, a meter will do.
I have sort of done this with my 2hp compressor and 20 liter tank.
Runs up to 120PSI, although it didn't need to be that high... Needed
to get a tennis ball over a high tree branch to haul up an antenna =D
I just use the dump valve in the output of the tank. Takes a bit of
practice, but works a treat. Short link hoses help ;)

cheers,

Kim

[Ken]

Hey Kim, why didn't you use the traditional method of lead weight fired from slingshot, trailing fishing line?

[Kim Hawtin]

On Tue, Nov 13, 2012 at 3:29 PM, Ken <k...@waggies.net> wrote:
> Hey Kim, why didn't you use the traditional method of lead weight fired from
> slingshot, trailing fishing line?

didn't have any to hand. slingshots are getting harder and hard to get ...
you can find very nice antenna lauchers on teh internets, but customs
love them even more.
i'm told that once you import something like a sling shot, you get on
a customs full cavity search list.
none of your imported packages are ever quiet the same again.

so a simple solution like using the air compressor sounded like a lot
more fun[1].

cheers,

kim

--
"Art without engineering is dreaming; engineering without art is
calculating." --SKR

[1] yes, even in the dwarf fortress sense.

[Andrew Helgeson]

Not wanting to be a wet blanket here, but...

You guys do realise this device you are discussing in an open forum is so illeagle its not funny?

The air cannon I helped Pro Hart design got him a huge fine, that was 20 years ago.

After Media Mike's weapon reform laws got passed stuff like this, amongst other things, are legally defined as an offensive weapon.

Andrew

On 13/11/2012 2:23 PM, "Steven Pickles" <thatp...@gmail.com> wrote:

Umm, I'm not sure what this would achieve as we already have a quite massive air compressor and it would still rely on dangerous PVC pressure vessel for compressed air, which I'm trying to eliminate, but yes, technically possible if the car pump can get up to sufficient PSI. 

The plan is to use the pressure vessel in the air compressor we have, and see if it can dump its load of air fast enough to launch something (I'm starting to think the answer to that is no).

pix

On 13 November 2012 13:52, Ken <k...@waggies.net> wrote:
>

> Would it be feasible to charge the PVC...

--
You received this message because you are subscribed to the Google Groups "HackerSpace - Adelaid...