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Knex Controllable Machine Gun Answered

This is where all future models of our machine gun will be posted. This is a project of a collaboration between me and theawesomestdude. We hope you enjoy. Suggestions and help and models and feedback are welcome.

Discussions

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sonic broom
sonic broom

5 years ago

So is this just a rubber band gun that fires one Rubber band for each trigger pull if so then maybe you should look at this gun it does the same thing but it has a much easier mech https://www.instructables.com/id/Knex-Rubber-Band-Gun-8/ i built it and it worked great.

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TheDunkis
TheDunkis

Reply 5 years ago

No, that's exactly the limitation we're trying to get over. We want a fully auto, but also controllable, slingshot. Normally, if you just let all the rubber bands go, they fire incredibly fast, seemingly at the same time you could say. It's more of a shotgun in that sense. And that's assuming it doesn't even jam up. So, we've been studying different methods to make a "controllable" full auto, that is it would fire at a slower rate. One of the methods I proposed (and others such as myOmy may have independently as well) was to create a mechanism where the band that was just fired will trigger the gun after it reaches a certain point. The difficulty in this so far has been making a strong enough trigger mech that can take the stress of upwards 8 bands but still be actuated by the force of just one band. You can see where physics isn't our friend here.

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myOmy
myOmy

Reply 5 years ago

I have a working prototype like the video shows, but youtube is being stupid right now . . . so yeah.

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TheDunkis
TheDunkis

Reply 5 years ago

Thanks, but I've no problem with the concept itself. I'm struggling to think up a trigger design in K'nex. I basically have the gist of what I'm trying to accomplish, a trigger mechanism that slides off the cog and catches it by like a hair, something easy for the power of one band to actuate. But I just can't figure out any combination of parts and layouts that do that. I ask for help and haven't seen a trigger like that yet. Meanwhile, people keep spitting out these proof of concepts and I get hopeful but then they say stuff like "It doesn't work well with more than 2 bands" and then it's back to the drawing board.

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myOmy
myOmy

Reply 5 years ago

I have a working prototype like the video shows, but YouTube is being stupid right now . . . so yeah.

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didexo
didexo

Reply 5 years ago

Guy makes sick guns.

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sonic broom
sonic broom

Reply 5 years ago

The gun that i gave a link to is controllable it fires one band upon pull of the trigger and can hold more then 8 bands

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TheDunkis
TheDunkis

Reply 5 years ago

But it only fires one band. That's called semi automatic. What we're talking if fully automatic, hold down the trigger and it'll keep firing at a consistent fire rate.

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sonic broom
sonic broom

Reply 5 years ago

okay now i get it hope to see a working gun made with this if it's so awesome. but any way why not just use a motor connected to the cog to spin it at a constant rate and pull the trigger to switch the motor of and on.

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TheDunkis
TheDunkis

Reply 5 years ago

Correct me if I'm wrong, but doesn't that work pretty much on friction? Like, he's only retarding the cog's spin, not actually controlling it? From the comments below, he's claiming it fires upwards 1200 RPM, still fairly fast.

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ooda
ooda

Reply 5 years ago

No, he's using a piston that moves back and forth. Momentum limits the ROF.

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myOmy
myOmy

Reply 5 years ago

Yep, precisely as TheDunkis said.

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knexguy237
knexguy237

5 years ago

This is pretty nice. I don't know if you've figured it out yet, but how will the full auto stop?

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myOmy
myOmy

Reply 5 years ago

I abandoned this for about a month because it was pissing me off but in the past week I have got a little farther than before. As of right now I have a theory of how I will stop it but I am not sure because the full auto mech is not fully complete. As of right now, it looks nothing like it does in these two videos. I have mainly been trying out different ways to make it have less friction by designing different cog/trigger designs. I know you are quite mechanically inclined so if you want to give this concept a shot, please do.

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TheDunkis
TheDunkis

Reply 5 years ago

Keep at it, man. Yeah, I struggled to find a good trigger and cog mechanism that had low enough friction. Literally years and years have gone by. And my thoughts for a trigger mechanism is there'd be a "real" trigger that the piston operates and then a user trigger that either manually operated the cog or the piston once and then would let it fire uninterrupted until the trigger is let go, then it'd either stop the piston or stop the cog from advancing.

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knexguy237
knexguy237

Reply 5 years ago

Yeah, I was thinking of starting to make this is try it. I feel like it would be fun, but I'd probably destroy it after it made me mad, haha. But yeah, I'll try this mech after a couple of guns I'm working on right now. You seem to be doing really good so far with this though!

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didexo
didexo

6 years ago

Interesting mech bruh.

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JonnyBGood
JonnyBGood

6 years ago

I'm intrigued.... I'm kind of interested to see how far you take this mech, mainly because it is a heck of a lot more complicated than I thought it was. You did however prove a theory that I've had for awhile now. I was predicting the first usable full auto would be a combination of both full auto and semi auto technologies. I'm just glad to see someone is fairly closer to figuring something out. Keep up the good work man!

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myOmy
myOmy

6 years ago

bump