Semi Auto Cartridge Hybrid Build Log (Lotsa pics)

[pneumaticcannons]

I'm in serious need of a new username

After pondering countless cartridge hybrid designs, I've decided to screw simplicity and see just how complicated this thing gets....

The ultimate goal is to get this thing to fire 3-4 rounds in rapid succession and to keep the total amount of actuators/motors/etc. down to one. This may seem to contradict the statement above but I'm looking for elegant complexity and not this.(though that's still awsum)

Since It will possibly be controlled by arduino, semi, auto, and burst fire (just for fun) will all be possible with a quick re-flash of the board.


What I have so far (only picture on front page that will actually be updated):
Looks clean.... but only from a distance.

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breech receiver next to the pneumatic piston which will operate the action... both turned on my drill press:




Ejection slot and where the mag will go. Re-enforced the pvc with some steel:


piston assembly installed:
The ejection process will be a bit... different. I can't really say how exactly it will function because I haven't even decided yet.




A disassembled, almost complete cartridge:


Here is where I need your help. I need to come up with a simple ignition system that can be easily duplicated on other cartridges. I'm trying to decide between 1: A sheet metal, circular cap on the back and a metal ring (tin foil maybe?) around the cartridge itself. And 2: A conductive ring within a larger one on the back of the cartridge. I could possibly use an etched circuit for this. For me, 2 seems like it would be much cleaner than 1, but I don't really like the idea of using that circuit etching crap. I've have bad luck with it in the past.

Anyone have any completely different ideas for the ignition?

[Zeus]

Have you seen the adhesive copper tape for leadlighting? Linky

And why the heck would you use Arduino? For $4.30 you can have one of these little beauties, and you don't have to learn baby level neutered C, it's just plain C. Also USB programming on board, only one PWM channel, and you get two processors in the kit.

[jackssmirkingrevenge]

Oooooh...

Hybrid carts haveplenty of energy, the most logical design would be a blowback breech that doesn't use external power to drive the mechanism.

[pneumaticcannons]

Have you seen the adhesive copper tape for leadlighting? Linky

Thanks Zeus, I'll look around for that. If all else fails I'll just super glue some tin foil to it.

And why the heck would you use Arduino? For $4.30 you can have one of these little beauties

True, I'm not be too fond of the idea of putting a 30 dollar arduino into something I won't take apart anytime soon. I'm actually thinking of using an ATtiny. I already have an arduino to program it with so why not.

Hybrid carts have plenty of energy, the most logical design would be a blowback breech that doesn't use external power to drive the mechanism.

Well, considering how much trouble you've had with blowback, I decided that there was no way I was going to pull it off with this little first attempt. If by logical you mean the path of the least cost, then yes, blowback would have been much cheaper. However, I got the 3 way and piston for free because my parents bought them to be used in one of my electives' final project.
See, school isn't all bad

[jackssmirkingrevenge]

I've had more trouble with the cartridges themselves than the actual blowback mechanism to be honest, heck I even made blowback work for a pneumatic

On the other hand, there are a lot of externally powered autocannon out there in the real world, so it won't look out of place, and kudos for being innovative

[pneumaticcannons]

I also wanted to be able to experiment with different ammo. I would have been restricted to a very small window of mass if I were to use blowback. I just did'nt want to mess with all that.

there are a lot of externally powered autocannon out there in the real world, so it won't look out of place

I sort of expect it to fit in with the paintball minigun types of launchers, in the functional-awesome-overkill category

[sagthegreat]

make a 20mm autocannon


http://www.google.com/imgres?q=20mm+aut ... s:16,i:134


Look at the pic

[jackssmirkingrevenge]

I sort of expect it to fit in with the paintball minigun types of launchers, in the functional-awesome-overkill category

More in the category of the bushmaster:

[youtube][/youtube]

[pneumaticcannons]

Edited now: I forgot to mention in the design criteria that I'm trying to keep the number of actuators/motors/etc. down to one because having too many actuators, motors, and doodads tends to slow rof and isn't much of a challenge. Extreme case. In order to do this, I made an ugly ejection mech today but hey, it works every time and doesn't violate my second design criteria I plan to cover all the moving parts in acrylic anyways.

I added a spring to aid in ejection as the magnet isn't strong enough on it's own (see video at bottom)
pink iz boss




ghetto but funcional

Here is an explanation and demo of the mechanism
[youtube][/youtube]

[wyz2285]

Looks cool but, hybrids are violent, rubber bands and pvc pipe doesn´t really belongs here

[pneumaticcannons]

The plastic is kinda my style But yes, the rubber bands and skewers are very sloppy and I've begun the process of replacing the bands with springs and the skewers are gone too. Soon it will all be inside a little box of acrylic.

[pneumaticcannons]

Apologies for the long delay in-between updates, I got distracted:



I recently got the ignition system working 100%
I had also gotten the new and improved ejection mech working but of course, minutes before making the video, one little metal part broke deeming the entire mechanism useless. Oh well
[youtube][/youtube]
All shots were done at 5x mixes

[warhead052]

I have to say Pneumatic Cannons, I'm highly impressed. For a kid who moves in between Countries (Yeah, I remember that...), this is impressive work! Very nice, can't wait to see the completed project! Any plans on what you are going to model it after?

[pneumaticcannons]

Thanks warhead
No, I really don't plan on modeling it after anything. Though I do expect it to look a bit like a 60's sci-fi gun once completed

For a kid who moves in between Countries

It's funny that you should mention that. In general, it seems as if the kids I meet in the states have more of a clue, while the kids over here who are always moving around, are closer to robots. Kind of sad actually.

[jackssmirkingrevenge]

Still ridiculously overcomplicated in my book but props for sticking with it