SpudFiles

Hello everyone,

I haven't been on here for quite some time but what was once a small hobby has given rise to a potential buisness opportunity. We are putting together a video shoot for a product in which we want to film powder in high speed (possibly with a Phantom camera). I decided to take on the task of building an automated powder cannon for the shoot so that we can create very specific timing and replicate shots.

I did some testing with a single barrel version and flour. It is a 40" barrel of 1" pvc with a 20" chamber of the same. It uses an orbit 1" unmodifies sprinkler valve. The results using about 3/4 of a pound of powder we're quite good.
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We want the powder to be thrown out of the barrel and not blown so I came up with a creative solution. The end of the barrel is ported to vent excess gas pressure. There is also a length of paracord that is fed in and tied off back by the sprinkler valve. On the other end of the paracord is tied a small was of fabric. The length of the paracord is just long enough for the fabric to travel past the ports but not out the barrel. This means that the fabric stops near the end sealing off the barrel and creates a rough seal forcing excess gas out the ports. Without this the powder is blown out like a cloud instead of thrown out. I have also found that increasing the pressure beyond a certain point does not help with the effect. It seems that flour can only travel through the air so quickly before is breaks up into a cloud itself from the air resistance. We are not worried about this as we only need a range of 5-10 feet as we are currently getting a range of over 30.

With this small scale test a success I moved on to replicating it 7 more times with a folded design using all of the same parts essentially.

This was the first full scale test. I actually ran out of flour so several barrels only had a maybe a cup of flour in them. For the video shoot we will be using colored Holi powder which is essentially cornstarch and food coloring. It will create a much more interesting effect though, especially in super slow motion. I also underestimated the recoil in this test and had the rig fly off the back of my impromptu cooler stand setup and

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The next step is to wire up an Arduino and an 8 channel relay to control the timing of each barrel. After that I want to get the filling situation improved and hide all the guts in some sort of covering.

I do have a few questions that I am hoping you all could help with.

1. I want to fill all the chambers at once. I envisioned using some sort of 7 way splitter to go from a single air source (bike pump) to all seven chambers at once. If I use a one way valve at each chamber I should get approx equal pressure and be able to just disconnect the bike pump and be ready to go! I am struggling to find a cheapish one way valve though. Their are air compressor check valves but they are $8+ each which seems silly. Then there are automotive and aquarium check valves that could work but I do not see maximum air pressure ratings on them. Any suggestions here would be hugely appreciated.

2. For the outer encasement I am struggling to come up with solutions. I want this to have a handle and be sturdy but it is also getting very heavy already. It has a diameter of about 12" so I considered 12" PVC ducting, but it's absurdly expensive online and I can't seem to source it locally. I need to to look cool and minimalist for the video shoot so again creative ideas from you guys would be amazing!

I hope you enjoyed the project rundown

Brad

well that's different

Here are some more build images. Ignore the build mess

PVC Nock Gun

Finished the sequential trigger system just now. It is setup to be adjustable in terms of delay between each barrel and it ignores multiple button presses within 5 seconds.

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If you haven't worked with relays before what is happening in the video is that I am using the weak power output of an Arduino to flip some high power switches which will be wired to a 12VDC lithium battery pack.

Now I just need to wire it up to the powder cannon

Awesome build!

Be very, very wary of sources of ignition in your shooting area though, accidental powder explosions aren't fun.

There are air compressor check valves but they are $8+ each which seems silly. Then there are automotive and aquarium check valves that could work but I do not see maximum air pressure ratings on them. Any suggestions here would be hugely appreciated.

These sort of check valves are only good for a few psi above atmospheric pressure, I wouldn't trust them at higher pressures.

These aluminum ones for fuel on the other hand should do the job safely.

For the outer encasement I am struggling to come up with solutions. I want this to have a handle and be sturdy but it is also getting very heavy already. It has a diameter of about 12" so I considered 12" PVC ducting, but it's absurdly expensive online and I can't seem to source it locally. I need to to look cool and minimalist for the video shoot so again creative ideas from you guys would be amazing!

It seems to be shame to cover the multiple barrels, maybe some minigun style support disks would work:

Thank you!

And yes we will absolutely avoid ignition sources. I was thinking about that as well. I believe the shoot will be in an empty warehouse and no fire will be involved. We will also forbid smoking.

I did come accross those diesel check valves and I think you are right about them being my best bet so far.

As for the encasement I am not planning to cover everything just the rear portion where we have the chambers and valves. I like the steampunk look it has now but for this video shoot it just isn't right. As for the gatling gun style flair I actually need to try to get away from that unfortunately. This is for a product video and not everyone is cool with guns these days so we want to walk that line between cool gatling gun and harmless powder launcher carefully. I fdont want to make it look boring but I don't want to make it look violent either...it's the world we live in

Braddubya wrote:This is for a product video and not everyone is cool with guns these days so we want to walk that line between cool gatling gun and harmless powder launcher carefully. I fdont want to make it look boring but I don't want to make it look violent either...it's the world we live in

Why would you want to pander to the perpetually offended though? I see your point, but at the same time, you've obviously built a device that is not made with violent intent, it's just a bit of fun so why walk on eggshells.

jackssmirkingrevenge wrote:

Braddubya wrote:This is for a product video and not everyone is cool with guns these days so we want to walk that line between cool gatling gun and harmless powder launcher carefully. I fdont want to make it look boring but I don't want to make it look violent either...it's the world we live in

Why would you want to pander to the perpetually offended though? I see your point, but at the same time, you've obviously built a device that is not made with violent intent, it's just a bit of fun so why walk on eggshells.

On one level I agree but on another level as a startup buisness promotion the goal is to get as many people as possible to get onboard with the product. It's the nature of buisness especially small buisness. Doing things the way I want to, in spite of the audience's preference, is not a wise way to do buisness. For example I may despise a certain color but I would still make a product in that color if that is what the market wanted to buy.

I appreciate buisnesses who don't inject their owners politics into their functioning on either side of the isle or on any topic. The goal of this is to create a stunning display that is relatively neutral in terms of ideology. Sorry that was so long winded but I think you raise a reasonable point and I wanted to address it fully.

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Figured I should post the final result. I ended up using 1/4 od tubing and push to connect fittings and check valves to accomplish the filling. The casement is a wood frame with plastic sheeting wrapped around it.

I wanted it to fire about once per second so filming in 240fps and playing around 30fps I figured that was around 8 times slower so I set the delay for 125ms. It seemed to work pretty well! We will be filming in 580fps or 1000fps making the delay more like 30-60ms.

I also ended up adding another button and an LCD screen menu system so that you can program the delay in from the back of the cannon easily. It saves me from having to hookup my laptop and reprogram the Arduino if I want to change it.

Now it just needs paint

I liked it a lot. With the appropriate colors it would give the visual impression of a weapon of "massive destruction". Good job.

Reminds me of this:



Hate to see the worky bits concealed but ah well great work!