19 replies to this topic

[CaptainSlug]

This is because of Prometheus who got me thinking about how to alter the original valve design to allow for a traditional trigger configuration. Took only a little while to figure out which size of O-Ring I would need to use to make this possible.

Since the pump will be connected using tubing I have the option of using a dollar store pump or a leftover stock Nerf Pump. I happen to have an RF20 pump handy that I can use.
Now I just need to wait for the parts to arrive.

Edited by CaptainSlug, 07 June 2007 - 08:46 PM.

[El-Cheapo]

Looks, simple, yet clean. Better looks than the Dchap-1. Sweet, I just may have to make one for myself.

[Athune]

Given that the trigger now sticks out of the air reservoir instead of the barrel assembly, wouldn't air leak out of the slot that the trigger sticks out of? What if instead you moved the trigger to in front of the valve? You would still loose some pressure when firing, but at least your air reservoir would be air-tight.

Edited by Athune, 07 June 2007 - 10:10 PM.

[CaptainSlug]

No, that's what the other O-Ring is for.

Edited by CaptainSlug, 07 June 2007 - 10:25 PM.

[Athune]

How does that second o-ring work exactly?

[CaptainSlug]

The rear o-ring seals against the outer diameter of the 1/2" rod while still allowing the rod to slide and open the trigger valve.
The tank ends at the rear o-ring. The rest of the pipe parts from that point on are simply acting as a grip with tubing running through it.

Drawing flexible tubing in CAD is a pain so I just drew it onto the diagram.

Edited by CaptainSlug, 07 June 2007 - 10:57 PM.

[Athune]

CaptainSlug, on Jun 7 2007, 11:26 PM, said:

The rear o-ring seals against the outer diameter of the 1/2" rod while still allowing the rod to slide and open the trigger valve.
The tank ends at the rear o-ring. The rest of the pipe parts from that point on are simply acting as a grip with tubing running through it.

Ahhhh! I missed the pink tubing when I was looking at the design. Very nice!

[Prometheus]

Very nice. A little more complex than the dchap-1, but probably more reliable in the long run. Glad I could have been of assistance.

[zaphodB]

How viable would it be to use the Dchap2 as a secondary resevoir for the Dchap 1 as a main resivior, enabling a semi-auto gun? Or at least one that can have a few shots per pump cycle. I guess you'd have to have an O-right on the push-button trigger, but would that be enough to hold the pressure?

[Cennipe]

Zaphod, are you saying that you could push down the "triger" form the Dchap1 and fill the Dchap2 tank, load a dart, and then pull the triger, repeat? More like a NF, where you cock, load, shoot, repeat; so you don't have to pump up each time.

Edited by Cennipe, 08 June 2007 - 03:34 PM.

[CaptainSlug]

zaphodB, on Jun 8 2007, 03:19 PM, said:

How viable would it be to use the Dchap2 as a secondary resevoir for the Dchap 1 as a main resivior, enabling a semi-auto gun? Or at least one that can have a few shots per pump cycle. I guess you'd have to have an O-right on the push-button trigger, but would that be enough to hold the pressure?

The DCHAP-1 leaks around the trigger rod so it wouldn't be very useful as an inbetween valve unless you could fix that leak. Two DCHAP-2 valves in sequence however would work fine. You would simply add one inbetween the main tank and the blast tank that outputs into the barrel.
Kind of like this with the pump or large air reservoir hooked up to the first valve. Then link the output of the first valve to in inside of the second valve.

Or even like this



You can use the DCHAP-2 valve in any configuration you want. It's just a matter of deciding where you want it. The DCHAP-1 valve on the other hand is really only meant to exhaust into a barrel.

Edited by CaptainSlug, 08 June 2007 - 04:05 PM.

[zaphodB]

The reason i ask is because it looks as if the Dchap-1 valve allows for a larger tank than the Dchap-2 does, because the valve mechanism is sort of inside the pressure tank. Also, as of now the projectile I want to launch out of my version would be rather large (2.5" diameter, at least) and weigh maybe .25 to .5 of a pound. It'll be covered in foam, and won't be intended to hit a person, but my issue is, will i be able to even fire it?

[CaptainSlug]

DCHAP-1 and DCHAP-2 can both be made with either a coupler or a tee so the size of the blast chamber is entirely up to you. DCHAP-2 should have a lighter trigger pull than DCHAP-1, but that problem is just an issue of leverage.

Edited by CaptainSlug, 08 June 2007 - 05:41 PM.

[Z-man12]

This is even more adaptapable then the original verson. I love this one even more then the first one.

[monkey with a nf]

Bringing this back, because I have something that seems like a problem.


I'm (finally- things kept getting in the way) building a DCHAP-2-based homemade. However, I'm wondering about one part of the design. Is the outside of the 3/4" endcap supposed to seal with the 11/4" PVC? With the one I'm using, there's a slight (something like 1/132") gap. Should I PVC cement it? Get a different cap?

[CaptainSlug]

I haven't tried to make this yet so I'm not sure. You'll need a mechanical hold as well as a pressure hold to keep any pieces in place.

[monkey with a nf]

I think I might just use another 11/4" to 1/2" reducing bushing in the back (where the endcap/SCH 80 contraption is), with a 1/2" stub stuck in it to hold the o-ring in place. Should work better than the current design (and I don't have to drill any 1/2" holes in endcaps, which is a pain if you don't have a drillpress).

Of course, then I have to order more bushings (but I had to do that anyway).

[ice]

Are you still trying to make it? Because it looks very intresting.

[CaptainSlug]

No, I never got around to trying to make one.