minipump pics (this thing is fun)

Post questions and info about pneumatic (compressed gas) powered launchers here. This includes discussion about valves, ratios, compressors, and anything else relevant to launchers powered by compressed gas.

Postby clide » Fri Feb 20, 2004 8:19 pm

I found this pen at school the other day and was taking it apart (like I do all pens) and I realized that it would make a really nifty ammo/barrel. So I was looking at it all day thinking of what to do. That night I went to the hardware store and picked up parts for my design.

Here's what I ended up with, a single pump, self contained mini coaxial in a tee:
http://members.cox.net/clide/minipump/fullclosed.jpg
http://members.cox.net/clide/minipump/fullclosed2.jpg
http://members.cox.net/clide/minipump/fullopen.jpg
The wood on the pump is to keep the pump centered.
http://members.cox.net/clide/minipump/pump.jpg
http://members.cox.net/clide/minipump/frontloaded.jpg
How it works:
The pump is pushed down to compress the air, when the end of the pump passes the hole for the hose, the air behind the piston is vented and POP!
The tee is 1/2" and the pump housing is 1"

I thought I was just going to use it for plinking around the house, but it ended up being more powerful than I thought. It put a small hole in the wall at 20 feet away, and bent the tip of the ammo when hitting the plastic around my window at 15 feet(also left a dimple in the window plastic)
http://members.cox.net/clide/minipump/ammo.jpg

I found that I could also use the core plastic peice from a bic mechanical pencil with a toothpick stuck in the rear as pretty good ammo.

The piston is made of a rubber stopper, and I used a homemade spring (paper clip) to reseat the piston.

Total it cost about $20. My trip to Ace to get all the parts cost $16, but I already had the pipe, the o-ring, and the pen.

Hehe, this thing is really fun, I'm off to play with it more :D
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Postby akb » Fri Feb 20, 2004 8:35 pm

Cute. A bit different from what I had in mind for a 1-pump pneumatic, but very ingenious!

-- akb
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Postby clide » Fri Feb 20, 2004 11:35 pm

Thanks for the compliment.
You do make me curious though, what did you have in mind for a one pump pneumatic?

I'll be looking for a real spring next time I go to the hardware store, the paperclip doesn't hold its shape to well, but it works for now.

I also found that if you take out the metal tip on the ink it gives you a nice ink splatter where you hit, although I probably shouldn't have tested that on my wall. :x
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Postby akb » Fri Feb 20, 2004 11:50 pm

I wrote something about it on one of these threads just a few days ago. Don't remember which. I was thinking along the lines of a QEV and a conventional trigger, and a lever rather than a straight pump, but your design has some really good elements.

I would still like to have a pushbutton trigger, but he tee valve is great. A DFTV would be nice, but probably overkill.

I think the main thing I would try to do is separate the pumping from the triggering.

We were talking - it was in the indoor gun thread I started, I think. A magazine fed ping pong single pump launcher, that's what I was thinking of. Something really fun and safe for in the house.

Anyway, great design. Took me a minute to figure out your trigger setup. Very clever.

-- akb
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Postby clide » Sat Feb 21, 2004 12:17 am

Yeah, originally I was just wanting to put a conventional valve on there and use something to hold the pump shut once it was pumped. Then I thought of this idea and I wanted to go for it because really the only thing I sacrafice is aim, but I am getting better at aiming and pumping. Plus without any extra valves it makes the whole project very cheap.

Heh a DFTV would definately be overkill for something like this, but it might be fun to make if you are bored.
That was acctually what led me to develop this. I was thinking that if I had a DFV type setup then I could have the pilot stop filling at a certain point in the stroke and when the pressure built up on the chamber side of the valve it would eventually move the piston and fire the gun. Then I realized that once the pump passed the hole then it would fire itself, and then I ended up with this.
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Postby chewy » Sat Feb 21, 2004 3:04 am

kudos clide. another job very well done. you never have to worry about running out of air. you will have to figure out a mag feed. than hook up the piston to a wheel and motor, like a steam locomotive and have a auto.:Dany idea how far it would shoot a pinpong ball? again great job.
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Postby Timmay10 » Sat Feb 21, 2004 10:04 am

Can someone draw up some quick diagrams on how this thing works?
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Postby clide » Sat Feb 21, 2004 12:29 pm

I may later timmay, but not now, in the meantime anyone else is welcome to draw it :)

chewy: I just tried to hook up a ping pong barrel to it. It didn't turn out to great. Not enough air can get through such a small hole to launch the pingpong ball. To see what I mean put a fender washer on the end of 1.5" pipe and stick a pingpong ball in there. Hold it vertical, then try to blow the pingpong ball out through the hole. It just bounces around at the bottom of the pipe making funny noises. This gun could probably be built slightly larger to launch pingpong balls, but I doubt they would go very far.

UPGRADE :) I put 1.25" pipe around the 1" and screwed it to the handle. Now it is much easier to shoot and aim because I dont have to extend my arms as much, as well as making the pump more stable.
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Postby akb » Sat Feb 21, 2004 12:55 pm

Great upgrade. Much better to reach.

-- akb
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Postby boogieman » Sat Feb 21, 2004 2:53 pm

Thats a cool launcher! Good thinking. Very clean looking too.
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