15 replies to this topic

[quertyman]

So I am almost done with my mad ghost and I am having problems. When i pump it up the trigger pull to open the 1/2 check valve is EXTREMELY hard to pull. I got the check valves at lowes. Also I did cut off the tip of the pump like 3dbbq said but it leaked air so i had to hot glue/epoxy it back on. Last I had to dremel out the 1 inch check valve so that the pump could fit and then seal the outside edge but its still leaking a tiny bit. (also this is my first post)

[Daniel Beaver]

You're probably either pumping it up too much, or there is some sort of physical obstruction. You can rule out the latter by just making sure making sure the trigger pull is easy while it's empty. I can't really think of anything else that might be wrong, it's such a simple mechanism. The force that counteracts the trigger pull comes from the air pressure pushing against the back of the valve seal, and it will be equal to (the pressure in PSI)*pi*( the radius of the valve seal)^2. If you have a way of measuring the pressure, it should be around 25-35 psi or so (don't go over 35 psi, it's overkill). 1/2" PVC has an inner diameter of 0.622, so I would imagine the valve is close to that size or smaller. Given those assumptions, the trigger pull should be, at the very most, about 10 pounds. That's pretty heavy, maybe even "extreme".

I'm winging some of the numbers here, so feel free to correct me. The 35psi figure is from... somewhere, and I can't quite remember the rational behind it.

Edited by Daniel Beaver, 07 August 2012 - 01:25 PM.

[quertyman]

That is exactly what is happening but I am only pumping it 2-3 times like 3dbbq said and this is a standard ball pump from sports authority. Also the valve kind of tapers to a bigger size it is the lowes check valve so I would say it is about an inch radius. I have to use my whole hand and push down on the nail to get it to release the air.

[Draconis]

You state both 1/2" check valve and 1" check valve. Which is it? 1" would fit the pump, but be horribly difficult to open at pressure.

[quertyman]

I followed 3dbbq instructions and have the pump connected to the 1 in valve and the trigger connected to the 1/2 check valve just like a normal mad ghost. But if you ever have seen the 1/2 check valve the outside radius is probably about the size of 1.25 PVC. Also the 1 in check valve had to be sanded out a tiny bit to fit the pump.

[Draconis]

Ohhhhhh, okay. I misunderstood. This is one reason that I always install a pressure gauge on my air blasters.

Edited by Draconis, 07 August 2012 - 02:28 PM.

[Ivan S]

If you put some sort of faceplate over the trigger bolt that allows you to pull with more than one finger it helps a lot. I use a ~2" long piece of 2" pvc pipe that's been cut to fit over the bolt and around the trigger tee. I'll post a picture once I'm back from vacation.
Just bracing the butt of your gun against you shoulder helps a ton too.

[quertyman]

I Am trying to do the 1/2 ring trigger but I am not sure how to attach it, maybe epoxy putty. And does anyone else have the same problem as me with the trigger pull?

Edited by quertyman, 07 August 2012 - 03:06 PM.

[BK201]

I've had a similar problem with the jspb style blaster I built. 30psi or higher made the trigger pull a little unmanageable, especially if you are trying to have a quick trigger pull to use the semi auto function of any of the newer jspb models. I've been trying to think of a lever style trigger that could be used for this to allow for an easier and faster trigger pull. I've been using mine spun 90 degrees so I can pull the trigger with my thumb, which kind of works.

[thebob13666]

I also had a similar problem on both the JSPB blasters I built. After I destroyed the check valve on my first when someone overpressurized it, I built the second. It still had a very stiff pull on the trigger, which was just a long bolt. I fixed this by taking a door hinge, one of the long triangular ones, and using it as a lever. I cut down one side so it was only about 3/4" long, drilled 2 holes, and screwed it in right above the trigger bolt. The other part of the hinge would lay down over the bolt, and give you about 1.5" of metal to hold on to, plus a good amount of leverage to push in the trigger. If you want pics just let me know, as I don't have any right now of it.

[quertyman]

Ya pics would be awesome and my main question is how did 3ddbbq do it?

[thebob13666]

I believe that 3DBBQ may have some slightly more efficient valves to use. I find the lever works perfectly fine. Here are the links to some pics, as I can't figure out how to directly post them...

Trigger lever resting position

Cut down edge and attaching screws

[quertyman]

That's a great idea I think I will try that next time I go to ace.

[thebob13666]

Just make sure you get some fairly heavy duty hinges. None of that brass crap or anything, there is a lot of stress where it contacts the bolt, and over time can bend slightly in the middle.

[quertyman]

where did you get your lever?

[Zorns Lemma]

where did you get your lever?

Its a regular door hinge. You can find them in any hardware store.