Semi-auto Vortex Cannon! (SUCCESS)

[shiddymunkie]

In the meantime, why not have some fun and shoot some projectiles like spudguns are supposed to

I would, but I still need to work out the design of the primary and secondary air tanks before the barrel comes in (plus I have something else I use for projectiles 8) ).

Since overall size is a concern of mine, and because I only have to worry about flow constriction with the smaller secondary tank (chamber), the primary tank is likely to be a bit....unorthodox. I've sketched a few things out on paper, but am still not quite sure what it's going to end up being. It doesn't help that I have no idea how much air will be needed to produce solid but efficient vortexes (or is it vortices?). I want to get at least 5 good shots out of each fill, but naturally the more the better.

On that note, I was actually considering a lego-like secondary chamber made of PVC extensions, where I could add/remove sections until I found the best efficiency-to-power ratio. Then, once I have the optimal capacity, I'd make a more permanent version out of a single stretch of PVC:

Just out of curiosity - what is shapeways charging you for that part? What manufacturing process and material did you request?

Not trying to steal business from them - just interested in the pricing mechanism they use!

In general, they charge by the cubic centimeter of material and the cost is calculated automatically based on the virtual volume of the 3D file. There is also a small flat fee they add on regardless of the volume (so they can still make money on tiny items). Here is the pricing for the "strong and flexible white plastic" I am having the cone printed out of. Also take note of this:

Density discount

We also offer a volume and density discount on Strong & Flexible materials. For models that have greater than 10% density (material volume divided by bounding box volume), volume above the first 20cm3 is calculated with a 50% discount.

Large, extremely low density models printed in White Strong & Flexible are priced based on bounding box volume rather than material volume. For models with a bounding box over 10,000cm3 and a density less than or equal to 2.6%, the price is $.0385 per bounding box cm3 plus a base price of $1.50. See our blog post to learn more.

Fortunately my model is 10.89% density.

[jackssmirkingrevenge]

I would, but I still need to work out the design of the primary and secondary air tanks before the barrel comes in (plus I have something else I use for projectiles 8) )

Nice! And yet you came up with this abomination?



Elastic bands?!?!?!

[shiddymunkie]

Nice! And yet you came up with this abomination?

Elastic bands?!?!?!

LOL

Yeah, that was on a different forum with Joerg Sprave. He is the founder of the slingshot channel, and makes all manner of elastic abominations. That picture in particular was from a thread where he was thinking of a way to make a chainsaw slingshot (yes, shooting a running chain saw) and somehow we just got off track on ideas. If you ever have any spare time browse through his videos -- there are just too many awesome contraptions to even call out my favorites.

[shiddymunkie]

I did a little work on the temporary tanks that I'll be experimenting with. As I was talking about earlier, the chamber will be made of threaded 3/4" extensions so that I can step the capacity up or down as needed, until I find the optimal balance between efficient air usage and good vortexes. Once I've determined what the optimal capacity is, I'll make a more permanent chamber of that same capacity.



For the primary air tank, I used a 20" remnant of 1" PVC I had lying around. Since this is only a temporary tank that I'll be using to find the best chamber size, it doesn't have to hold a lot. Once I know what the optimal chamber size is, I can then figure out about how large my primary tank will need to be in order to get X shots out of it. So for now, it'll do.



Oh, and on a side note, something serendipitous happened with this longer/skinner tank. I've found that I can open the slide valve much faster with a "pool stick" like thrust of the tank as opposed to pulling back on the valve itself. I haven't lubed the slide valve up yet, but as it stands, the thrust technique is at least twice as fast. I'm hoping that 2" vortexes don't require much air to be formed and fired effectively. This was originally meant for "cubicle warfare" so I'd be happy if this rig will shoot them a good 50 feet (indoors) and still have enough "umph" to get someone's attention. Even 30 feet would be okay.

[jackssmirkingrevenge]

If you ever have any spare time browse through his videos -- there are just too many awesome contraptions to even call out my favorites.

Joerg is a member of spudfiles too http://www.spudfiles.com/offtopic-relat ... 19034.html

Have you thought of a regulated paintball tank as an air source?

[shiddymunkie]

Briefly. I suppose I just assumed the greater PSI ratings of a paintball tank wouldn't mean much in a design that's currently limited to the 145 PSI rating of the QEV. I didn't even think to integrate in a regulator -- my whole focus was more on the dynamics of the vortex, with the air supply sort of being an afterthought. I think it was also a matter of assuming this cannon would be powered by some sort of manual pump since it would live at the office (again, making higher PSI applications tricky). I am digging on this tank though



But now that you mention it, I guess it makes a lot of sense if I can find the right one (size, price, etc). Know of a good resource for those regulated tanks?

[shiddymunkie]

Update:
- Schrader valve has been ordered (should arrive this week)
- 160 PSI pressure gauge was ordered and has arrived
- 160 PSI manual pump ordered (should arrive this week)

I've been watching this video quite a bit. 0:07 - 0:12 shows that a stable vortex can indeed be formed from a ~0.5" aperture, at least at very low pressures. At 1:15, a similarly-sized vortex is shot from what looks like a half-liter water bottle, being powered by popping a small balloon (which I assume is at no more than 1-2 PSI)...but it required the addition of a straight ~5" barrel for the vortex to form. This vortex was able to travel at least 5', i.e. across the short span of a standard 4'x8' sheet of plywood plus an extra foot or so to the white cloth.

Since my barrel is about 2x as long, 4x the size at the major aperture and conical shaped, hopefully it'll support significantly higher PSI and still form stable vortexes. I'm starting to have doubts about how compatible high PSI and small vortexes are, though. Then again, this seemed to work with what looks like a 4" vortex...

[mobile chernobyl]

In general, they charge by the cubic centimeter of material and the cost is calculated automatically based on the virtual volume of the 3D file. There is also a small flat fee they add on regardless of the volume (so they can still make money on tiny items). Here is the pricing for the "strong and flexible white plastic" I am having the cone printed out of...

Thanks!

Seems competitive pricing. I wonder if their "Strong and flexible plastic" (lol) is actually some form of Nylon - if shapeways is using SLS process which seems to be the common point amongst all their materials. Nylon is a great material and has great layer-to-layer bonding properties!

[shiddymunkie]

Seems competitive pricing. I wonder if their "Strong and flexible plastic" (lol) is actually some form of Nylon - if shapeways is using SLS process which seems to be the common point amongst all their materials. Nylon is a great material and has great layer-to-layer bonding properties!

Yep, I'm pretty sure I read it was nylon somewhere on their site. Let me see if I can find it....

Strong & Flexible plastic is printed with an SLS process that uses a laser to fuse together nylon powder.

To print in this material, we start with a bed of Nylon powder and sinter the powder with a laser layer by layer, solidifying the powder as we go. Because of this layer by layer process, some products may see a staircase effect. How much you see this effect depends on how your model is oriented in the print tray. Our production planners are working hard to orient models optimally to ensure efficient and good lookin' trays.

[shiddymunkie]

Just came across this video of a "Whamo Air Blaster" from back in the 60’s. What's interesting about it is, like the vortex ring gun, it too uses an "inverse" cone to create the vortex. I was under the impression that this type of nozzle only worked with air traveling faster than mach 1? I'm all sorts of confused now...which style works better? Can they work in conjunction with one another??

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also came across this
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[jackssmirkingrevenge]

But now that you mention it, I guess it makes a lot of sense if I can find the right one (size, price, etc). Know of a good resource for those regulated tanks?

A typical 48 cubic inch 3000 psi aluminium tank is a good low budget choice. Unless you live in the hinterland it should be easy to find a place that will refill it for you.

A tank fitted with something like the Ninja SLP regulator will have an output of 300 psi without the need for an external regulator. You need an ASA head that will allow you to connect the bottle to any male 1/8 NPT fitting.

If you want to go lower, Palmers Pursuit is the place for you.

[shiddymunkie]

A typical 48 cubic inch 3000 psi aluminium tank is a good low budget choice. Unless you live in the hinterland it should be easy to find a place that will refill it for you.

A tank fitted with something like the Ninja SLP regulator will have an output of 300 psi without the need for an external regulator. You need an ASA head that will allow you to connect the bottle to any male 1/8 NPT fitting.

If you want to go lower, Palmers Pursuit is the place for you.

Whatever air source I end up going with, I will need to reg the PSI down to 140 - 150 max because of the QEV pressure rating. I was having trouble finding a paintball tank with an output that low, which would seem to imply that I'll need an external regulator anyway (like the one you linked me too). But with the cost of a tank, regulator, ASA, etc...this has all got me wondering if it would be more cost effective to simply get a cheapo paintball gun + tank combo and somehow replace the barrel with my cone.

But perhaps I'm getting too far ahead of myself...I'm not even sure if the cone will work! (much less how much air, and at what pressure, produces a good vortex from that cone). I guess I'll just need to experiment a bit with my current set up to figure out the details, and based on that information, figure out the best way to improve the design.

[jackssmirkingrevenge]

this has all got me wondering if it would be more cost effective to simply get a cheapo paintball gun + tank combo and somehow replace the barrel with my cone.

You might have hit on something there...

But perhaps I'm getting too far ahead of myself...I'm not even sure if the cone will work! (much less how much air, and at what pressure, produces a good vortex from that cone). I guess I'll just need to experiment a bit with my current set up to figure out the details, and based on that information, figure out the best way to improve the design.

Well, you can make a vortex by slapping a box

[shiddymunkie]

Well, you can make a vortex by slapping a box

Indeed, but I'm not sure how the physics of that approach is going to translate into something that uses compressed air, valves, and a cone. Naturally, the goal is to pack a more powerful vortex cannon into a smaller package, but with so many variables changing, it's hard to predict whats actually going to happen.

This is even true of my design and highvoltagefeather's build, despite it being a more direct translation than a box with a hole cut out of it. And while his worked, he also had a different air capacity, different valve system, and a different cone size. Without really knowing how well vortexes scale (or the mechanisms that form them) I'm not sure what to expect.

[jackssmirkingrevenge]

cut a hole in a box[/img]

Class!

Indeed, but I'm not sure how the physics of that approach is going to translate into something that uses compressed air, valves, and a cone. Naturally, the goal is to pack a more powerful vortex cannon into a smaller package, but with so many variables changing, it's hard to predict whats actually going to happen.

True, true.