Monday, May 30, 2011

Air Canon

I am writing this up because of a request from Maurice to do so.

After reading Maurice’s article on the Air Canon he built, I was sure there was a way of building one that would be able to fire via an electronic system.

So I went on a scavenger  a hunt in my Sons shed and what I found was a 12v Solenoid, an old Butane Gas  blow torch, and because he loves his Old man, I had little trouble in removing them from his possessions.

Putting it all together was fairly simple, I use a piece of acrylic sheet for the base plate, this proved a little to flexible, so I glued a piece of aluminium channel on the underside to stiffen it up. This also acted as a channel to run the cables from the Projectile sensor to the CameraAxe.

I Bolted the solenoid to the base, fitting the tank was a bit of a problem, but I ended up forming a bracket from some aluminium 2mm X 25mm Bar (1/8 X 1inch ). glued this to the tank, and drilled the solenoid cover and the tank to it.

The gas tank has a valve in the input, this I drilled out with a 6mm drill, I also enlarged the opening in the trigger fitting, the trigger itself was sawn off, I found an old flexible gas pipe and cut a portion long enough for my needs leaving a fitting on one end, the other end was forced onto the gas fitting, and retained with a hose clamp, I now needed a means of pressurizing the tank, for this I use a valve from and old bike inner tube which was forced into where I had removed the gas tap.

The barrel was a length of aluminium tube bought from the local hardware, this was flared at one end, though this was not really necessary, as I could have quite easily glued it in place.

The hardware finished I had to come up with a means of firing it, what I was looking at was a means to trigger the camera as well as the solenoid.

Thanks to Maurice and his great articles I had been playing with the Arduino for a while, so decided this was the way to go. I designed and made a shield board to do this, the Electronics was simple enough, but having no knowledge of programming made things a little more difficult, but again thanks to Maurice’s articles, I gleaned enough to get it running.

Now came the test, I pumped it up using a hand pump quite hard work I might tell you, and it worked first time much to my surprize, though the pressure was very low, I got the use of a compressor, and much to my delight it built up 100psi very easily, this is when I discovered that the solenoid would not trigger above 60psi, it worked to a degree, but not how I had hoped for.

I found a solenoid on ebay that would fire up to 140psi and at a reasonable price $25.00. http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=130502647805 , There are many different voltages and pipe sizes available, I chose the 3/8 model.

When it arrived I found it to be a touch larger than the previous model also the fittings were slightly different, so had to alter the design a touch, The pipe fitting can be got at your local plumbing supplies.

I wasn’t able to fit the tank to the solenoid, and because I was afraid of damaging the tank if I tried to remove the bracket I decided to mount it to the side, just a matter of drilling a couple of holes.

Again came testing time, Would it give a trigger at 100psi, !!!YES!!! and the first result is below. I am looking at changing  the electronics,  I designed a new circuit board which now incorporates the Arduino chip, and all necessary sensors, I was looking at triggering this via a remote control, but so far haven’t been able to get enough info about it,  anyone with any ideas on this, your help  would be much appreciated, please leave a comment. I will stay with what I have until I can see if it is worth the trouble

What I like about  this design is I have plenty of scope where missiles are concerned, so far I have tried ball bearings, pencil stubs and I have made some from the nozzles from silicon tubes, and the screw driver bits all work well.

Why did I decide to make this, well simply put, the gun laws here are very tight, to much of a hassle to get a licence. Probably illegal, but not dangerous to anyone but me, could you imagine me hauling a compressor around, I think not.  

I am sure there are many more items to be found that would do just as well to build this, But please be careful, make sure you work safe, and don’t hold me responsible for any injuries or damage that may occur while using it. You make it at your own risk.OLYMPUS DIGITAL CAMERA

Layout of the circuit board That I will probably end up using.

Air Canon

OLYMPUS DIGITAL CAMERA

P1080132

I prefer the look of version 1 , but version 2 works much better because of the higher pressure allowed by  the solenoid.

If anyone wishes further info please email me at erniehatt@yahoo.com.au or leave a comment here.

A few safety ideas.

1 load the missile,2 set up the target, 3 do your CameraAxe setup, all these things before pressurizing the Airgun. hope this is of some use.