I guess this could go under modifications because I was working on my blastfire, but I specifically want to focus on the check valve.
I've noticed an increasing number of "My check valve isn't working!!!" threads. This is a problem I've had before and it didn't take long before it happened again, so I thought I'd take a stab at solving this problem.
Before we begin, there are two things I'd like to make clear.
-It's much easier to replace the check valve than repair it. Find another pump and connect the vinyl tubing with larger ID tubing. The reason I wanted to keep this pump so badly is that I think the blastfire looks incredibly cool and replacing the pump would break my heart.
-The finished product did not work in this case. This was a proof of concept however because it did work prior to installation in the gun.
First off, remove the back end of the pump with the check valve.
Take out the gasket and clean out all the bits of plastic. Take the plastic shell and dremmel the hole until it's wide enough to fit one of these:
This is a simple hose connection piece. I salvaged it from my sisters nebulizer. Now she's gasping for air and I have a sweet blastfire that doesn't work yet. This part doesn't have to be exact, you could use anything that will connect to the vinyl tubing on the other side. This is just what I happened to have.
Now, the piece I used had two sides. One attached to the hose and the other was threaded. Cut off the threaded side so it's a flat plane against the back of the check valve and glue it down.
Here's how the new check valve works:
Starting at the left, the tubing that connects to the internals will go inside about a two inch piece of 3/8" vinyl tubing. Now inside this piece of vinyl tubing will be a BB. The BB will rest on top of the pneumatic connector. See how it works? Air can go past the BB when you pump the gun because the BB has wiggle room inside the 3/8" vinyl tubing. But back pressure pushes the BB against the opening of the connector making it airtight.
You should have something like this now:
However, there's a problem. The smaller ID vinyl tubing can also be blocked by the BB, sealing it on both ends. To fix this, I shoved a pin through the 3/8" tubing a short distance from the stock tubing.
Now it should work. I tested it by blowing into both ends. Sure enought, air could get in through the pump end, but not from the recieving end. This was my proof of concept.
I plumbers gooped everything together and covered the holes created by sticking in the pin. The problem happened when I put everything back in the gun. The handle on the blastfire was too thin to keep the assembly in a straight line. It instead curved up towards the trigger from the end of the pump. The BB didn't seal against the tip of the connector like it did when it was straight and thus the gun still doesn't work.
It's a little rough, but with some improvements, I believe this could be very useful to anyone who's pump doesn't work.
EDIT: I should make a note that this could work much better if the whole assembly is aligned straight, preferably vertically. I attached the 3/8" directly to the back of the pump, but if everything was moved up say, into the handle, I would expect much better results.
Going further, the little pnematic piece I attached at the back of the pump has almost the same ID of the stock vinyl tubing. The BB can rest against the end of this vinyl tubing and work just as well, although I would recommend putting another pin in to make sure the BB doesn't get stuck inside the tubing.
Edited by BlackFox, 02 September 2008 - 04:47 PM.
