Schrader threads to small?

[theBOOM]

I'm in the process of building the mini cannon for the mini challenge contest. It's actually a mini hybrid, the spark and schrader valve are epoxied to a male adapter, the problem I'm having is that the pump I have dosen't open the check valve on the schrader. I'm wondering if a different pump might solve this problem or will I have to redo the whole thing? I believe the problem is being caused by the lack of "area" for the schrader attachment to cling on?

Here are some pics to illustrate what I'm talking about. Thanks.

[Gun Freak]

It's probably the pump.

[theBOOM]

Bah, I hope it is, if not I'll go to my grandmas and see if it works with a compressor.

[qwerty]

You could try glueing a small peice of wood or something like that to the pin that pushes the schrader down.

[theBOOM]

I could do that but I would probably make a mess beacause of the small area I have to work with.

[clemsonguy1125]

Some bike pumps dont fit car tire valves, but most bells do, try taking it to a gas station and hooking it the compreser, if its not the pump this should loosin it up enough for it to work in the pump

[Mr.Sandman]

Wow boom that looks really nice. Good job with the epoxy. If it isnt opening the schrader check valve then just keep pumping at it will let in the air. If not then there is something wrong with the schrader.

[Gun Freak]

I think the opening pressure of a schrader is 70 psi without pushing the button so yeah, just keep pumping.

[clemsonguy1125]

I think vhman's schrader check valve on his hp pump cracked at 75 psi

[theBOOM]

Okok thanks guys I'll try it again tonight, im going out to eat with my family... Thanks sandman

[saefroch]

The schrader valve will not open at all if the pump is not connected, the pin must be pushed down- at least I know this happens up to about 120 psi- and a great way to extend the pin if that's what needs to be done- put a drop of solder on the top of the pin... I've never tried it, but it should work on a small-scale apparatus like this if you've got a steady hand.

[theBOOM]

Oh, I know that the pin has to be moved down for it to allow air in, the problem is that the hose dosen't reach the pin beacause of the lack of area for it to "cling" on.

What I'm going to try and do is move the "pin" up a bit with a schrader tool I bought some months ago, does anyone know if this will reduce its pressure rating or make it malfunction for some reason??

[Mr.Sandman]

Oh, I know that the pin has to be moved down for it to allow air in, the problem is that the hose dosen't reach the pin beacause of the lack of area for it to "cling" on.

What I'm going to try and do is move the "pin" up a bit with a schrader tool I bought some months ago, does anyone know if this will reduce its pressure rating or make it malfunction for some reason??

First of all what pump are you using? If it threads onto the schrader then you are fine. But if its a quick release then you have a problem. Try oiling the valve stem and if that doesnt work then just use the valve tool.

[theBOOM]

It's the stupid quick release type, and it's kind of old, so I think that might be the problem also the "rod" that presses on the schrader pin is too far back for it to reach the schrader. I actually lost the valve tool, I'll try and find it tonight before going to sleep.

The compressor in my house has some weird fitting on it, so tommorow I'll go out and buy an adapter so I can use it on the schrader valve.

[Mr.Sandman]

It's the stupid quick release type, and it's kind of old, so I think that might be the problem also the "rod" that presses on the schrader pin is too far back for it to reach the schrader. I actually lost the valve tool, I'll try and find it tonight before going to sleep.

The compressor in my house has some weird fitting on it, so tommorow I'll go out and buy an adapter so I can use it on the schrader valve.

What you could do is take some thick walled metal tubing and tap it with some 7mm threads and you will have a quick functional adapter. If not, then loo around at hardware stores in the bins of random parts and see if you can fund something threaded that will fit the schrader.