40 replies to this topic

[Carbon]

This concept comes from somthing davidbowie talked about in the original SNAP-1 thread, using a syringe and syringe head as a plunger tube. Last time I was at the surplus store, I bought a small 20 mL syringe. It's been sitting there ever since. When I was cleaning my parts drawer this weekend, I found it, and thought it would be fun to try and use it, especially after the height of technology that is the SCAR.



I was just messing around with it at first. First order of business was to eliminate the nozzle and enlarge the airway.


I wanted to test it to see if it was even worthwhile, so I e-taped it to some 1/2" PVC. Damned if the thing didn't get some range (tight mega stefans in PVC)...

Of course, just hitting the end of the plunger doesn't make for good accuracy. So, an internal spring was needed. Turns out the plunger came apart nicely, and I hacksawed off the cap. I happened to have a good size spring around.


I cut slots in the end of a small dowel, and then glued the plastic to the wood. The plunger rubber actually fit directly on the wood, but there would have been nothing for the spring to attach to, or push against. You can also see the trigger notch. I decided the easiest way to get thing thing going was to use a Nerf technique, and make a notch that can catch against the back hole. Push down on the rod to fire. It'll wear quickly because it's just a notch in wood, but this is just to get it going, anyway.



As it happens, the 20mL syringe I used has nearly the same diameter as 1/2" PVC. All it needed was one turn of e-tape to make it snug.

Good things about the concept: a syringe has a really good seal.
Bad things about the concept: a syringe has a really good seal. I don't have a very powerful spring in there, but it doesn't pick up much velocity.

Oh, and I just realized, I really need to trim that dowel. Duh.

It currently can get about 30' (measured) with really tight mega stefans. Here's a movie of it firing...if only because the sound it makes cracks me up.
PopGun

Is this practical in a war? Right now, of course not. But it looks like a syringe might be a nice source of ready-made plungers for other homemades. Easy to work, and cheap...the one I used was 40 cents.

Edited by Carbon, 15 July 2007 - 08:14 PM.

[Renegade]

That sound gives me the giggles. *giggles*

How's the dowel staying back under the pressure of the spring?

Nice job. It reminds me of Frost Vectrons homemades. I made one of his using bungies, PVC, and an at2k pump. Fun to use.


Edit/ Thanks Carbon. I probably should of read through the whole thing before posting. But the sound was like all hypnotic/Edit

Edited by Renegade, 19 March 2006 - 06:03 PM.

[davidbowie]

Whoa man, I can't get over the sound it makes.

I've got 3 20ml syringes as well, but I haven't used them yet, except for an airsoft springer that kinda sucked.

Just yesterday I got two old-style TTG knockoffs from Dollar General for $1 (pretty good deal actually, it gets about 25' stock). One broke, and I lost a few of the parts needed to fix it. The spring would probably fit quite well in a syringe, though. Hmm.

[Carbon]

Yeah, the sound made it all worthwhile. My modded NF actually sounds a lot like that as well.

The dowel is staying back because of the notch in the pullrod. The notch catches against the hole in the endcap, holding it in place. It's similar to most Nerf guns, except that I don't have a spring-loaded catch moving against it, I have to move it up against the hole.

[ompa]

I always wanted to do that; I've had syringes in my room for at least 4 years.

But now, I HAVE to do it. In fact, I'll do it with all 4 of my syringes, just so I don't have to live without that glorious sound.

~ompa

[Carbon]

I dressed it up a little bit (I had a handle around that was a bit too small for a SNAP), and a pull knob.


Now it just needs a proper trigger. Currently, I just sort of smack the plunger.

Discovery: don't lube a syringe with silicone! Whatever it's made of, it causes it to bind up like crazy. Water works best. Which, considering the original purpose, makes sense.

Edited by Carbon, 10 August 2010 - 07:06 PM.

[davidbowie]

Is that a wine stopper? Nice.

That's a good point with the water. I've been using silicone, which would explain why mine keep binding. Thanks.

[GeneralPrimevil]

That is awesome...

Those things make really good seales, hence the "thwooop." If your NF makes that sound, you must have a very good seal betweem the piston and the cylinder.

I think I'm gonna concentrate on other things at the moment, but that looks like something a few of my friends might make. I'll tell 'em about it, especially because they have connections with a hospital. Bar needles, it's freeee.

[CaptainSlug]

This gives me another weird idea for a design. Plus even if it's not accurate enough to hit someone with the noise would imobilize your opponents with laughter long enough for you to shoot them with something else.

Edit: Just realized that if you want a looser seal to allow for more plunger velocity you might be able to replace the rubber seal with an O-ring with a slightly smaller OD.

Edited by CaptainSlug, 19 March 2006 - 07:56 PM.

[Denaeron 12]

<cracks up upon hearing firing sound>

Great, now I have to get myself one of these syringes.
Nice work!

So it gets about stock NF ranges?
Not bad at all...

For a trigger, could you just make an assembly that knocks the dowel off for you?
Instead of something complex to fit into a notch on the dowel...

[six-five-two]

Awesome! I knew someone would make a nerf gun out of a syringe.

I can get mine for free, I just go to the park and look around in the bushes

Edited by six-five-two, 19 March 2006 - 09:49 PM.

[Carbon]

db: Yeah, it's a cheap champagne cork. I always save little plastic bits like that.

General: I did the e-tape wrapping thing with my NF. I can hold my hand over the barrel and *stop* the plunger...it's got a nice seal. I'm getting even more of a pop here because the megas I'm using really have to be crammed into PVC. It's more like a cork gun than a Nerf gun.

Captain: Looking at the plunger head, it has three separate lines on the head to form a seal. I could probably cut one, or even two of them off, and the speed would increase.

Denaeron: Yeah, stock NF is a good comparison. I get best results when I give the barrel just a bit of silicone. I've got a few assemblies in mind for a trigger...something that just holds the rod down, and then releases it, mostly, simple as possible.

652: I'm gonna assume you're kidding (I hope), but... I should clarify a bit more about the syringe I used; there was no needle involved in what I started with. It's what would be called an "irrigation syringe", like this. Don't mess around with syringes with needles; it's neither safe nor sanitary.

[NerfMonkey]

I'm pretty sure he was kidding because in all those AIDS awareness comics you see the little kid at the park, looking at a needle in the bushes...

Or not.

But yes, I've got one of these syringes, they're used on cows, just put a needle into it. I love it.

[sam]

This is a sweet idea, and add trigger and it will be an awesome holdout weapon. You should mod it to shoot micros to get some more distance.

[Carbon]

Okay, good, I haven't seen those AIDS comics. I'll take it as funny now that I know the reference. Sorry if I was jumpy, but I hadda make things completely clear...when I'm here talking about turning syringes into popguns.

I gave a few tries to getting it to shoot micros, and it just didn't work. Mainly that was because I tried a quick and dirty method (Crayola barrel). I think it'd work if I used 17/32 brass and my snug stefans...I'm out of that size right now, though. The plunger in this gun is slow enough that it's using the pressure buildup to fire the dart, rather than plunger velocity.

[six-five-two]

Well here in vancouver, there is this park where there is a bunch of needles, i was there and they were playing in the bushes....

So... where can I get that syringe?

[boltsniper]

That's pretty damn cool and ridiculously simple too. If you get a simple trigger setup on that it could become a easy to build pistol. Using a syrigne was a great idea. You should try one of them giant syringes that are like 30mm or larger.

[Carbon]

So... where can I get that syringe?

Most any medical or science supply store will have them, in a variety of sizes. I got mine at American Science and Surplus. (One of their locations is pretty close to my house.) I'll be checking back for other sizes...when I was there, they had the 20mL size, and a glass one.

Edited by Carbon, 20 March 2006 - 07:30 AM.

[JSkater]

Hey, I've got two of those sitting around my house.. I might just try this, just because the sound it makes is great. Awesome job, Carbon.

[The Infinite Shindig]

I am very happy with how the Homemades forum has been going recently. Keep up the good work guys (bolt,davidbowie,carbon). If I missed anyone, my aplogies. You guys are really showing some of our members what this forum was intended for.

[CaptainSlug]

Okay the design that was inspired by this thread is actually quite simple. Since syringes are so cheap and effectively operate in this configuration as a spring plunger it would be fairly easy to make these in sets so that they could be arrainged in a clip or drum magazine. The advancing cycle of the magazine could have a groove track that as the magazine advances will prime each syringe in sequence and then release it.
The magazine would need to be advanced with either a crank or an electric motor, but the end result would be a multi-fire nerf gun that requires no pumping and no trigger mechanism.
If advanced with a crank the gun would be very similar to the razorbeast but without the flaky belt-feed system. If motorized the rate of fire could prove quite impressive.

I'll work up a design later tonight, this is really exciting.

Edited by CaptainSlug, 22 March 2006 - 06:09 PM.

[davidbowie]

Whoa, you're definitely right on with that, captainslug.

The other cool thing is that, with the trigger system Carbon has right now, you could use a lever directly connected to the trigger to nudge the pull rods out of their locks. I had a similar setup once for a rubberband revolver. It worked decently, at least as a proof-of-concept.

I'm thinking it would be nice to use the rotation mechanism from any nerf revolver (AT3K, FF, Mav, etc.) with a few of these on it and an added firing lever.

[CaptainSlug]

If done in the way I'm describing no trigger would even be required because if the plungers are primed on the advancing cycle they can also be released by it automatically once they reach the desired point in the cycle. You simply have the track drop-off at some point allowing the plunger to fire.

The trigger would be either negated entirely for the crank, or simply be the on-off momentary switch to activate the motor.

I haven't even thought of this as a possiblity previous due to the cost required and the complexity of having to make some many plugners and tubes, but being able to buy packages of syringes negate both of those downsides and would require minimal modification.

Edited by CaptainSlug, 22 March 2006 - 06:17 PM.

[davidbowie]

good point, I guess you could just have a wedge there to knock the piston rods out of their notches.

Since I like semi-auto more than full, I would still go with the rest of my design, but since i'm probably not building this, it's not my decision.

[Carbon]

That's a great idea!

The only thing to consider about using a wheel for both priming and firing is that the syringe makes a ridiculously good seal. As in, when the tight stefans needed for firing are loaded, you can't prime the gun...it makes a vacuum.

What would help that design would be to increase the speed of the plunger, so looser stefans could still give range. I think the syringe head needs some surgery...

Edited by Carbon, 22 March 2006 - 07:15 PM.