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Solenoid Dart Gun?

not air powered

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#1 Trace II

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Posted 22 July 2007 - 11:49 PM

So my friend was telling me about solenoids (for those of you who [like me] thought that solenoids were just sprinkler valves, it turns out they are electo-magnetic thingies where, when electicity is apllied, they either shove a rod out, or shove it back in depending on the type.) My idea is to put a plunger on it and make a spring gun- without the spring. Would this work? Are their solenoids with the power and speed to do this? Has anyone ever tried/thought of this? Is my "?" key going to break from over use?
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#2 General Cole

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Posted 22 July 2007 - 11:58 PM

They work differently than you think. Yes it pushes a rod, but that rod is fairly small in my knowledge and moves only enough to open a gap for air to flow through.
We should stop calling out/making fun of/pissing GC off. He's actually contributed and is available for trade. He's a better than average member no doubt. Got your back Cole.

You know what... I know it's kinda late... but Props Cole.

#3 Thom



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Posted 23 July 2007 - 12:15 AM

Nah, if you want to skip the air stuff, then you want a good, old-fashioned railgun. Don't shoot it at anyone you like, though, and I'd recommend against using it to fire anything made of polyethylene.
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#4 Athune



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Posted 23 July 2007 - 08:06 AM

Nah, if you want to skip the air stuff, then you want a good, old-fashioned railgun.

I agree. If you're going to make a electromagnetic nerf gun, rail guns are much simpler than coil guns (which use solenoids). Wikipedia has pretty good descriptions of both.
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#5 MithMorchaint



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Posted 23 July 2007 - 12:44 PM

I concur. All of the solenoids I've dealt with only move the rod about an inch (at most, many are less than that).

As for the sentiment on a railgun...that's immensely dangerous and not something I'd attempt on a whim. Yeah, the idea and the gun are cool, but do you know what happens when there's a malfunction? The rails can vaporize and the gun shoots flames...and that's only one of the possible meltdown results. I wanted to make one a while ago, but decided against it because of their sheer potential for catastrophic failure. Not to mention, the amount of capacitors and wiring needed makes it an impractical weapon at best. Further, you'd need the technical know-how to make a decent one, so it would depend on who is making one.

Then again, I'm thinking of a fairly powerful one. Maybe a small one would be less dangerous, but it also wouldn't shoot very far.

Finally, for a railgun to work on a nerf dart, you'd have to build a metal launcher for the dart. Railguns, as far as I know, only shoot metal (read: ferrous) objects or magnets. A dart is clearly neither, so you'd have to add in the extra piece that holds the dart, shoots down the barrel, then suddenly stops at the end, launching the dart. I need hardly say that this is going to put alot of stress on alot of pieces in the gun, especially the rails, end cap, and launcher component. You can pad the inside of the end cap that is impacted to reduce the stress, but this will decrease ranges.

The better option would, if you are committed to using electromagnetism to launch a dart, be a coilgun. It uses the same idea, just executed differently. Google will give you alot of info on them, but basically it is a tube with a sequence of coils that are given surges of electricity in sequence, pulling a metal object forward. I've been working on one for a while.

The trick with a coilgun that would make it better suited for this project is that it could be modified for this purpose, such that it would not require capacitors or much power at all, really. When a coiled-wire electromagnet is "on", the magnetic field it generates is directional - meaning, if you put a magnet in it, it will be pulled in one direction. You don't need a series of coils if you use a magnet for the projectile, just one long one. Clearly this is not practical when launching the object you're firing - the magnet - but if you cap the end as suggested for the other one, you could make it fire the dart while keeping the magnet inside. Simply make the firing tube (PVC with wire wrapping it tightly, covered by another piece of PVC) with a cap on one end (PVC with a hole big enough for the dart to go through) and then put a pvc cap over the magnet (facing the right way) with a piece of tubing on it to hold the dart, and there you are.

I really don't think you'll get much range out of this though. It shouldn't work very well in this application.

But let me tell you what I think would work. You said you don't want to use air pressure, but it's alot more efficient than trying to catapult the dart with a coil/railgun. However, a coilgun or railgun could be used to create the air pressure. Basically, use the idea I just had for the coilgun catapult - a tube with wire, a magnetic launcher - but instead of putting a cap with a dart-holder on it, put a plunger on it. Use the magnet to push the plunger, creating air pressure. Then just attach a barrel at the cap with the hole in it and put the dart in there. The plunger will act as any other spring-powered gun's plunger would, creating air pressure that goes into the barrel to fire the dart, but you should have an unlimited capacity for power with this gun. More electricity in the coil = faster plunger = larger ranges. For power? Just a few 9-volt batteries. To put the plunger back in firing position? Reverse the current to propel the magnet backwards, to the other end of the tube.

Not a bad idea, really. Might try it myself. It's basically the idea you had originally, just on steroids.

Edit: Forgot to mention, the magnet being used for the plunger needs to be polarized to work.

Edited by MithMorchaint, 23 July 2007 - 01:05 PM.

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#6 Trace II

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Posted 23 July 2007 - 03:56 PM

So it sounds like the best idea is the electromagnetic plunger. I'll try this and see how it works.
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#7 younggunner



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Posted 25 July 2007 - 04:08 PM

I designed a gun an paper a while ago that used electro magnets to move the plunger. I never built it though and i dont plan to. It seemed like to mmuch effert when i could get the same result with a spring.
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