6 replies to this topic

[MAC]

What do you think of my first homade?
I tried the two valve system, but it suked so i just use one of the valves now.
I put a checkvalve in the pvc and use a sm1500 pump. It takes about 40 pumps to make it shoot real far. Should i make the air tank smaller so that it has more pressure?

http://img.photobuck...33/2fc3d4bc.jpg

Edited by MAC, 31 December 2004 - 01:39 PM.

[Ironman]

You could do that or get a bigger and better o-ring for the pump.

[Doom]

Before we go anywhere, take note of the proper spelling of "homemade." Some hooker didn't make this gun for you (hence ho-made).

If you make a pump in that way, you'll need to use two check valves. One check valve prevents air from going back out into the open air and the second keeps it pumped into your pressure chamber. I'm surprised a design like that pumps air at all. I'd suggest buying real check valves as homemade ones tend to not work as well (believe me, I've made my share). Save up another $12 depending on the cost of two 1/2" check valves in your local area.

I'd also slap a real barrel on this gun (cut off between the two check valves and add a coupler). You'll need a pretty long barrel to work correctly on a ball valve. That might mean you should make your air chamber bigger. If you intend on keeping the ball valve trigger, I'd try some way to grease it or otherwise make it open faster.

Good for a first homemade I suppose.

[Techno-Dann]

A word of advice on the barrel: start long. Very long. My homemade has a tank made of a 19-inch section of 3/4 in. PVC, and it shoots quite well through a 30-inch barrel. For a homemade as big as yours, I'd suggest that you start with three feet or more.

[MAC]

If you make a pump in that way, you'll need to use two check valves. One check valve prevents air from going back out into the open air and the second keeps it pumped into your pressure chamber. I'm surprised a design like that pumps air at all. I'd suggest buying real check valves

I'd also slap a real barrel on this gun (cut off between the two check valves and add a coupler). You'll need a pretty long barrel to work correctly on a ball valve. That might mean you should make your air chamber bigger. If you intend on keeping the ball valve trigger, I'd try some way to grease it or otherwise make it open faster.

Good for a first homemade I suppose.

I am using a "real check valve"
Its a fishtank one that fits perfectly inside of 1/2 pvc and makes an airtight seal. I don't need two.
I do have a barrel but i just removed it. It fits inside of the valve because the end of the valve acts as a coupler.

[Langley]

If you make a pump in that way, you'll need to use two check valves.

I am using a "real check valve"
Its a fishtank one that fits perfectly inside of 1/2 pvc and makes an airtight seal. I don't need two.
I do have a barrel but i just removed it. It fits inside of the valve because the end of the valve acts as a coupler.

You would need a second check valve to allow air to come into the pump tube, but the pump handle you are using is set up so that it leaks on the out-stroke.

Edit: is that sched 80 you're using?

Edited by Langley, 02 January 2005 - 08:51 PM.

[Oddball]

You know why it sucked with two valves? Two reasons:

1) The pressure needs to be BEHIND the dart if it's going to push it out. You open the valve closer to the tank first, to let the pressure in, right? Well then what's going to happen is that you open the valve at the end of the gun, most of the pressure comes out, and the small amount of air that was behind the dart doesn't do much. A simple way to remedy this would be to tilt the gun forward, but then accuracy goes out the window, and eliminates the main purpose of a non-rapid fire gun.

2) I assume you used valves so that you don't have to pump as much, right? Well, it's not going to work so well since Your PSI is going to go down every shot, (That is, of course, if that tiny tank can hold enough air for a few shots) because when you let air into the barrel, your air has more space, right? so it expands, you close the barrel, and now the pressure in the tank is lower. Repeat, and your ranges go "Ploop".