10 replies to this topic

[Flaming Hilt]

I'm going to skip the fancy introduction, partly because I'm not bored, partly to piss off the bored people, mostly because it's midnight.

Homemade pump guns (not springers):

Pump, one-way valve, maybe an air tank, and then a trigger. Right?

I have never had any success. It's not because they don't seal right, or because it takes me 500 pumps to shoot 5 feet, or because my dog eats them as soon as they're finished. I can just never get them to hold pressure. I pump them once or twice... no pressure. I can pump them 10 or 100 times, and no pressure builds up.

There is NOT a leak. I can hear leaks. I can underwater trick leaks. The problem isn't leaks.

I thought the problem might be my one-way valve, but my latest attempt uses a high-end bike pump going into a tire valve, which was previously used to pump the tire up to at least 70 psi... but it can't pressurize my latest contraption.

I really see no other problems. So, I'm asking for help. And, as much as I hate to beg for quick responses, NO SPAM is in less than a week. Thus: The sooner, the better.

[quiet asian man]

You say that you get no pressure and that you hear no leaks, and for sure the pump is working.

Then where is the air going?

[Foam Shooter]

Is the one way valve facing the wrong way? You may be pressurising the area between the pump and one way valve if it is facing the wrong way. I know it sounds obvious but I would double check.

[Ryan201821]

How big is your airtank in relation to your pump?

The airtank itself doesn't need to be big at all. I mean look at the airtank of a 2k. It's tiny.

My suggestion is decreasing the size of the tank and/or increasing the size of your pump.

[PointBlank]

I would guess that the problem probably lies either with the barrel or the trigger mechanism. Make sure that the air cannot escape around the dart and that the trigger releases the air quick enough to move the dart down the barrel.

Pictures would be nice also.

[Flaming Hilt]

Quiet Asian Man: I believe the air comes out when I pull the pump back out,

which leads me to...

Foam Shooter: Yes, as I said, the bike pump/tire valve combo worked when the tire valve was part of the tire, so the one-way valve works -- or at least it worked when pumping the tire; but, I don't see when it could have broken or what could have gone wrong.

Ryan: Probably about 1/3 the size of the pump shaft. I realize that air tanks don't have to be very big (the 2k is always my example as well). However, I don't think volume is the problem here -- I did try pumping it 50 times, to no avail, and that many pumps should compensate for the large volume, shouldn't it?

In a previous gun, I could get a little pressure -- one or two psi worth -- but that was it. I could still pump the gun, so it's not that the pump couldn't handle it. I was thinking it might be a problem with the one-way valve, but one-way valve don't exactly have maximum psi, do they? Plus, as I said, this setup had no problem getting a bike tire to >70 psi.

PointBlank: No, what I'm saying isn't that there isn't enough air to move the dart, what I'm saying is that there just isn't air AT ALL.

[Ryan201821]

Then I'm guessing it has to be the valve. It must be damaged in some way.

Replace the valve and see if that works. If not, I really don't see how you could have a problem.

[zaphodB]

My guess is the problem is with the connection between the valve and the tank, and not the valve itself.

[Quilan Fett]

Likely the pump seal- add some e-tape under the o-ring.

[Ryan201821]

Likely the pump seal- add some e-tape under the o-ring.

He said the pump works perfectly fine up to 70 psi on a bike tire, so that's not the problem.

Hilt if you cannot figure it out, bring it up to NO SPAM and I will gladly take a look at it.