SpudFiles

This all started about 7 months back when I wanted to build a better Nerf dart gun for my boys. While they were out of town I built this for them.

It uses a stadard Orbit 3/4 inch sprinkler valve with pilot tube removed and remaining orifice drilled out to the max diameter (MUCH better performance that way). It is a 1.5 to 1 ratio cannon. The aluminum box underneith holds a small emergency air compressor pump (removed from the stock plastic housing) and a small lithium polymer battery. This gun can run autonomously all afternoon without a recharge assuming the pressure is kept reasonable. I have pushed it to 125 psi, but generally I stay around 50psi or so for most shooting. At 125 psi it will fire a nerf dart 645fps according to my Chrony. I also shoot Delrin slugs of my own design as well.

This gun has been alot of fun and problem free for many hundreds of shots.

Let me tell you, once a kid fires something like this, he will never go back to a regular Nerf gun!

Matt

Cool finally i see some body corporate a compressor on a air gun. looks great, the only parte i didn't like is the battery, but is necessary . You could put a magazine on it

Don't ever put 125 psi in that thing ever again. Keep it under 70. You used DWV parts (not pressure rated). But other than that it looks nice, clean, and fun.

It is hard to see in the pictures, however, the only DWV part is the 2 to 1-1/2 inch reducer at the end of the pressure tank. Every other part is pressure rated.

Matt

I know, but the cannon is only as strong as it's weakest part. I never said the whole thing was unsafe. The bushing doesn't go all the way in either. That is two unsafe things.

The bushing is bottomed out into the reducer. It is longer than the reducer, however.

I am not trying to argue. I get your point. If the tank ruptured, I would rather that joint go and merely launch the tank forward, than to have the tank wall rupture. Also, as I built the gun, I looked closely at that fitting. It has greater wall thickness than the tank itself. So, I was not very worried.

In any event, I agree with you wholeheartedly about the pressure.

When I built this gun, I never intended to go above 50psi. Of course, I have obviously gone beyond that. But, that was only a couple shots. For one thing, it takes a long time (3 or 4 minutes) of compressor time to see 100 psi. But, it only takes 30 seconds to see 50 psi. There is a diminishing return happening there.

Also, beyond 70 psi, the slugs (either Nerf darts or Delrin slugs) do not fly straight. That, along with the high pressurization time, keep the pressure down 95% of the time.

Actually, the vast majority of shots are at 20psi or under in our yard. It is amazing how far a Nerf dart will go on only 20psi!

Matt

Ya they flies great even with a 1/2 ball valve gun with a 15 psi 1.5 l plastic bottle my first airgun shots they to more than 80 meters

The volume of that chamber could easily be reduced without drastic performance issues, that would make the battery last longer by not forcing it to run as much. Try playing with the #s in ggdt to determine the best chamber volume.

I have considered that as well. Not a bad idea.

I want to move the chamber to directly behind the valve anyway. So, a new chamber is in order. Heck, I even have sch 80 parts here I could use.

The GGDT is no longer down-loadable.

Do you have a copy I can use?

Matt

High-PSI wrote:Let me tell you, once a kid fires something like this, he will never go back to a regular Nerf gun!

Got that right!

Now just keep the holes out of the siding......

High-PSI wrote:I have considered that as well. Not a bad idea.

I want to move the chamber to directly behind the valve anyway. So, a new chamber is in order. Heck, I even have sch 80 parts here I could use.

The GGDT is no longer down-loadable.

Do you have a copy I can use?

Matt

why is it no longer downloadable?
ill see about getting you a copy.

Since you're moving the chamber behind the valve, maybe you could make an ergonomic stock shaped chamber to give it more of a rifle look.

Lockednloaded wrote:Since you're moving the chamber behind the valve, maybe you could make an ergonomic stock shaped chamber to give it more of a rifle look.

That was an idea I had for a metal cannon. The tank would look just like a rifle stock.

Matt

Works for me.
http://thehalls-in-bfe.com/GGDT/download.html

metalmeltr wrote:

High-PSI wrote:I have considered that as well. Not a bad idea.

I want to move the chamber to directly behind the valve anyway. So, a new chamber is in order. Heck, I even have sch 80 parts here I could use.

The GGDT is no longer down-loadable.

Do you have a copy I can use?

Matt

why is it no longer downloadable?
ill see about getting you a copy.

AWESOME gun!!! Love everything about it!!!