7 replies to this topic

[Jappo]

Ok with the idea of the a Nerf bow I once owned I got an idea of a gun that worked on the principle of using a plunger to push the air rapidly forward. I took a 12" section of 1" PVC and stuck a 14 " 1/2" peice of PVC with a lubed end cap on the end. It created a semi-airtight seal. I then proceded to add a 1" to 1/2" coupler to the end of the 1" PVC and then added a 5 " section of 1/2" PVC for a barrel. To propel the plunger forward when you pulled it back i used an old bike tube (Yes I am that cheap). Sadly when the whole thing was put together it the plunger did not return fast enough to fire a dart more then 15'. It was also very hard to pull back and keep it steady. To correct the problem of the distance you could use a better spring (I.E. a trampoline spring), but this makes it very hard to pull back.

Just thinking about it now, you could mod this gun with a longer barrel, but it at a 75 Degree angel and put some buck shot in it to use it like a mortar. If anyone has ever tried to make a gun like this and have it succed, please post away. If you have any comments about this mod please do tell. Some constructive critiscm would be helpful.

PS this gun is not at all acurate unless you have extremly strong arm muscles to hold a taunt gun perfectly aimed and to release it without moving. Thats all I got today.

[TualatinNerfer]

you deserve a metal for trying on somthing original.

[xedice]

I have attempted at a homemade plunger gun, my set up was a little different. I had:
1.) PVC pipe for the case
2.) Rubber washer with wooden dowel attached for the plunger (lubed)
3.) 2 stretched stingray springs behind the plunger for the force

Well, I tried it out, but it just couldn't shoot nerf darts far enough, same problem with yours, even with the massive 2 springs for the power. I think the problem was that the rubber washer didn't make a good seal with the PVC. I think thats the problem with most homemade plunger guns. But I did hear Frost Vectron used lubed up leather for his plungers, and it worked really well. Maybe we should try that...

[cxwq]

I'm currently reworking my xbow with a completely new plunger. Planning to use a PVC endcap with o-rings in grooves. I'll post details when I get around to making it work.

[Langley]

What are you using to make the grooves?

[cxwq]

My prototype is a 1/2" PVC endcap with Dremel-induced grooves. I used the small metal cutting bit. It's slightly too big to slide smoothly in the xbow plunger tube so I'm going to try cementing a small piece of 1/2" PVC inside so I can cut the grooves deeper. If that doesn't work then I'll find something slightly smaller diameter than the PVC endcap but I want it to be a commonly available part so that others can easily duplicate it. Either way, I think a Dremel and a steady hand are requirements for this approach.

[Nello]

Access to a laithe would make machining those grooves in the endcap much easier, but I'm guessing that most of us don't have metal laithes in our basement workshops. It might be worth a try to see if you can get access to one in a machine shop, or a school tech shop.

Anyway, it sounds interesting, but I don't know where to buy o-rings from. Do most hardware stores have them, or do i need to look in a more specialized shop?

[xedice]

Home Depot has many O-Rings, but I get so frustrated with their stupid O-rings. They never form a good seal with the inside of PVC, well generally. The PVC measurements are always freaking different. I wish they standardized ID of my local PVC...

Anyway, sounds like fun cxwq. When you said it doesn't slide smoothly, is that with or without lube? I always have trouble finding a balance between smooth sliding and a good seal. Thats the only thing setting me back from creating a homemade plunger gun that can outrange my maxshot.