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A way to make a real k'nex fully automatic gun Answered

UPDATE: I have begun to construct a gun out of this. It doesn't shoot very far in the video because I am using a motor to power it, but once I complete it I'm hoping that it'll be pretty powerful.

Video: http://www.youtube.com/watch?v=LJbFasz1eAg

Original Post: It occurs to me that you could use a crankshaft with a motor or wound up rubber-band to push and then subsequently pull a firing pin in your gun. This coupled with a hopper that can push rounds into the chamber, and you would have a truly fully automatic gun, as opposed to a ton of single-shots all on a chain (which is cumbersome to load).

I'm not good at all at actually designing k'nex guns (not anymore anyway), but I did put together and example of a crankshaft, and have attached photos and videos to this topic. The actual crankshaft at the back of the example could easily be elongated so that you could have your firing pin travel farther, and if you put that axle on a small gear attached to a larger gear which is on another axle with a rubber-band or motor to turn it, you could get at least 20 shots from the gun. Reloading it would also be really easy, as you could have a crank to turn the main axle allowing the rubber-band to build up potential energy once again.

Sorry if this is confusing, I'm not the best orator or typer as it were, but I think the pictures will be a lot easier to understand.

Sincerely,
Black Leopard

Video: http://www.youtube.com/watch?v=Gbmm3BaAQgc

Discussions

that was my idea for the m4 carbine just moded to be more powerful, but you posted it first so its your idea.... by the way i got the idea from a car engine's piston, how did you get the idea?

UPDATE: I have begun to construct a gun out of this. It doesn't shoot very far in the video because I am using a motor to power it, but once I complete it I'm hoping that it'll be pretty powerful.

Video: http://www.youtube.com/watch?v=LJbFasz1eAg

wait does this have to have a rubber band cause in the new video it doesnt looks like it has a rubber band

The model in this video does not use a rubber band, but a motor. The final gun may use a motor with more transitions between gears to make it faster, or rubber bands, depending on which makes the gun shoot farther.

will never work lol or u could use an extremely fast motor to push the bullets out.

But you wouldn't use a motor. Instead you would use a rubber band wrapped around the axle with the big gear on top of it. Alternatively, you could keep ramping up the speed and lowering the torque (which you don't need a lot of for a k'nex gun) to make the motor produce something really fast. You'd only need to add one or two more axles to my current design to make it about 8x faster than the motor.

What is the purpose of the tan connector on the blue rod connected to the ram?

it keeps the joint from turning, so that the crankshaft doesn't get locked up because it can't bend correctly.

now i get this idea nice idea but are you gona put a magazine or something on it

i could make a better example with a magazine, but I'm not planning to make an entire gun out of this because I'll just make something horrible. I think if someone else took a crack at this the gun would end up being a lot better. I could try though.

i dont get it and the video doesnt work

sorry about the video, I'll have a fix for it shortly.

Assuming that you don't know what a crankshaft is, wikipedia has a good picture: http://en.wikipedia.org/wiki/Crankshaft

Basically, it allows you to turn an axle that pushes a piston (or in our case a k'nex rod) back and forth. This constructed into a k'nex gun would give you a fully automatic gun (the rod goes out, a bullet falls in, the rod comes back in pushing the bullet out, the rod goes out, etc.)