Relay Switch + Hand Crank Phone Charger =?

[renegadecow]

I'll just ask here before making a thread in the projects section.

Basically put, I want to make a ye olde Colt 1874 Gatling Gun and only now have thought of a seemingly simple way to make the gun fire by spinning the crank shaft. The gun will be electronically driven firing from the center like Killbuckets minigun, but instead of the usual trigger switch actuating it, I'll be hooking it up to a relay switch connected to a hand crank mobile phone charger. Theoretically, if I crank it fast enough, I'll generate enough voltage to trip the relay switch making the gearbox fire... right? And would there be a way to have the rof reflect how fast your'e working the crank?

[bankz5152]

That sounds like it would work, dont see any reason why not. As for ROF I dont think youd be able to crank it fast enough in order to change ROF that much really.

[astagg]

Yes should work you would have to get a relay with the correct voltage trip though. The ROF wont be affected as you are only powering a relay you can only produce a one or off for the main circuit. In order to effect the ROF you would have to make some advanced circuit with a voltage detector and the you could work with that.

[renegadecow]

Right, thanks. I haven't looked at the available voltages for both the relay and the charger, but I'm sure I could find a compatible pair. It's still a far off project though, but now all the more confident in making it with this method. I suppose variable rof does seem much for an electric system. I did however think op of a mechanical (not very practical) system for it. Other than working the barrels by the crank, it's also connected to a conveyor belt or chain with protruding tabs. These tabs trip the actual trigger of the gearbox which is set in semi-auto so however fast the crank is rotated will reflect directly on rof. Will probably need a mosfet though as I imagine the contact switch would burn out in no time.

[shmook]

This may sound stupid (I was always ###### at electrics), but could you not incorporate a rheostat in the crank assembly somewhere to vary the ROF?

[Bane]

Renegade, i've built a real gattling gun (hand cranked) at work and can supply some basic ideas on how to make a hand-cranked geared version that doesent require electronics, and in fact will function just by using AEG springs and pistons?

[renegadecow]

rheostat

I guess that will do. Maybe put the knob on the handle. Wont change rof by the crank, but since your'e holding the handle to aim it anyway, you could adjust it manually.

 

 

hand-cranked geared version that doesent require electronics

Sounds too dicey for me. I was looking at the innards of a real one last night which is why I just gave up and started to think of using electric. Nothing set in stone just yet, so you're more than welcome to toss in your ideas in case I come across the right parts for it.

[Stuey]

How's this for an idea: have the crank attached to a wheel which has teeth like a gear, but more rounded. Have this wheel activate a microswitch, one of the ones with a little wheel on the tang. This is connected to your MOSFET equipped semi auto gearbox. Voila, a simple mechanism which can fire the gun and vary the RoF on its own.

[renegadecow]

With a microswitch I'd need to add a burst circuit that's turned down to 1 shot.

[FELDJAGER]

If youre still planning on using a central barrel, What if the crank was attached to the gear train? even just a sector gear? no motors or batteries. that would give you the variable ROF you want.(mehbeh)

[ertgunner]

this may sound stupid, but can't you just use an amp for what you want to do ? (sure it will have a default when its turned slowly but you should be able to speed it up by turning it faster)

 

i have actually been planning a similar project but an mechanical version like the real one

 

 

EDIT: i forgot what they call it but they have a device that goes up/down in resistance depending on how fast its moving.

 

 

i know this sounds stupid but you can also link the handle to the actual gears. It won't be nearly as good of a workout as the real one but it will have adjustable ROF depending on how fast its cranked.

[Stuey]

With a microswitch I'd need to add a burst circuit that's turned down to 1 shot.

 

Oh yeah, sorry I forgot with a MOSFET the trigger switch still functions normally. In that case, depends whether you prefer working with mechanisms or electronics. My idea is simple mechanically but requires more electronics. Others will be simpler electrically but need more mechanical systems.

 

Edit

i know this sounds stupid but you can also link the handle to the actual gears. It won't be nearly as good of a workout as the real one but it will have adjustable ROF depending on how fast its cranked.

 

Dayum, now that's not a half bad idea! Certainly very simple (in theory).

[renegadecow]

What if the crank was attached to the gear train?

I imagine that's what Bane was suggesting earlier. Just extending the shaft of the sector gear will give 1 shot per turn. The sector gear will have to be meshed to a larger gear first as real gatlings will churn about 2~3 shots per turn of the crank.

[CHIFF_MoA]

If you're only firing from one central barrel an AEG with an adjustable rate of fire setup (like the A&K M60) would make sense in this application. Hand cranking the barrels is the only sensible way forward I think. Creating a stable enough current from your proposed set up would probably be quite difficult, not to mention that you probably dont have much of an operating window for the electronics, you may have to crank that handle far too fast!

 

If you are motorising the barrels as you suggest, you will need some sort of reduction gearing anyway to achieve the low speed of those early hand cranked rotary guns. If you are doing gearing anyway, you may as well make the hand crank drive the rotation. What I'm suggesting I guess is to keep the firing mechanism completely disconnected from the rotation of the barrels for the sake of simplicity. Some kind of push to make switch in the crank handle could act as the trigger.

[Bane]

Go for a simpler solution, seriously

 

The original gattling gun worked off bolts traversing a single cam, the firing pin would operate along a secondary cam.

 

For the airsoft version, its quite simple, six AEG pistons and springs, six AEG cylinders

 

To get the drive gear, use an old cheap angle grinder, they have a bevel and a pinion gear, use the pinion gear on the main shaft to rotate the barrels, the crank on the handle

 

I will have to get photos to explain better, but you simply function it the same way as the real thing, exept the piston replaces the firing pin, and the bolt becomes the nozzle/cylinder assembly. With the rotation of the handle, the cylinder runs along a cam, moves 6mm back to load one round, then forward again to chamber, the piston is drawn along another cam until it reaches its highest point, then released, which is where the gun would fire.

[Yuri]

What if you used an AEG gearbox set to semi-auto and made some sort of collar piece for the barrels with ridges on it corresponding to each barrel. Then make a lever that when pushed by the ridges will inturn push the trigger. Then you just crank the barrels and the gun will fire. The rate of fire will perfectly mach the speed the barrels are spinning at. The ridges on the collar piece would need to be shaped correctly so that they keep the trigger depressed for the duration of a single shot, otherwise the gun would missfire. Actually it might start firing sporadically if spun too fast, maybe that's realistic, I don't know.

 

In my opinion something like this would be both mechanically and electrically the simplest solution.

[renegadecow]

Go for a simpler solution, seriously

six AEG pistons and springs, six AEG cylinders

LOL U MAD? Firstly, I don't know how much confidence you have in me, but it's obviously more than I do for myself. Secondly, the 1874 fires on 10 barrels. That's 9 too many cylinders/pistons/springs/barrels/hop chambers for what I'm willing to shell out for. What you're proposing would essentially be a hand cranked P3 minigun and I'd need some serious hardware to machine parts for that to be anywhere near durable.

 

In my opinion something like this would be both mechanically and electrically the simplest solution.

Yes, my thoughts exactly. From my initial query, I was proposing only the gearbox to be electric. The barrels themselves will be mechanized and I've already designed (in my head) a conceptual drive train for it that uses cheap RC gearsets if I couldn't fabricate them myself out of PVC. Linked to this merry-go-round of death would be the crank phone charger which when turned to speed will generate voltage closing the relay switch and activate the gearbox. The thoughts of an adjustable rof was just a bonus.

Actually just thought of a way to make a rheostat work even better. Think speedometer needle. Attached to the crank is a wheel with a slip clutch. On the clutch is a stick. Spinning the crank at different speeds will have the stick move relative to it and at the end of the stick you have the rheostat.

[Yuri]

Actually just thought of a way to make a rheostat work even better. Think speedometer needle. Attached to the crank is a wheel with a slip clutch. On the clutch is a stick. Spinning the crank at different speeds will have the stick move relative to it and at the end of the stick you have the rheostat.

 

Is this like a volume knob style rheostat? You would need a spring that returns it to its original position, right? Otherwise it would just get cranked to eleven and stay there.

 

EDIT: So will you be running lots of current through the rheostat? If so, I hope you can find something that can handle it. Another possibility would be to make an amplifying circuit that's somewhat similar to the usual airsoft mosfet, but instead you'd be amplifying an analog signal. I personally don't know how one would go about doing that but I imagine it's pretty straight forward. Just need to find the right kind of transistor.