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Schrader threads to small?

Discuss miniature cannons built from things such as pill bottles and pen caps.
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Unread postAuthor: chinnerz » Sun Apr 25, 2010 11:47 pm

so what you guys are saying is, the pump either fits on the threads and pumps beyond 70-75 psi (open the check valve). or it fits on the threads and pushes the pin inwards(opening the valve.)

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but what you are saying is there is not enough area of threading for you pump to get a grip. hmm...

i would say that your pumps fitting is at fault here (may just be worn out if it is plastic and old, and those quick release ones which are plastic don't tend to last very long before the start slipping). i agree that some further investigation with different pumps is in order.
try and see if you can find a pump with on of these, as it has the best grip
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Unread postAuthor: Mr.Sandman » Mon Apr 26, 2010 5:21 am

chinnerz wrote:so what you guys are saying is, the pump either fits on the threads and pumps beyond 70-75 psi (open the check valve). or it fits on the threads and pushes the pin inwards(opening the valve.

But what you are saying is there is not enough area of threading for you pump to get a grip. hmm


You got the gist of it. But his pump head is a quick release one made out of plastic and those usually require a sufficiently long stem, and since his schrader threads are halfway covered by epoxy, it wont fill and the pump head won't stay attached. Basically he needs to find a pump or compressor with a threaded fitting that screws onto the schrader threads.
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Unread postAuthor: theBOOM » Mon Apr 26, 2010 7:21 am

Chinnerz, yep, that's the other way I was going to go around the problem, I'll try and find a small pump that has this type of "thread" in check valve. If I can find it I'll make myself a mini shock pump to go with the cannon.

Video of pump in action -
http://www.youtube.com/watch?v=ywC04etbHVY

Edit- I'm kind of worried that these thread on check valves for schraders don't actually depress the pin on schraders. Would I be forced to pump to 75 psi?
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Unread postAuthor: Crna Legija » Mon Apr 26, 2010 8:55 am

they do you can see a a little pin in the middle
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Unread postAuthor: theBOOM » Mon Apr 26, 2010 3:08 pm

-_- wrote:they do you can see a a little pin in the middle

I don't think we're talking about the same thing here, I'm talking about the checkvalve on pumps, not on the schrader, I know that the schrader does have a pin which is depressed to allow air in.
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Unread postAuthor: Lentamentalisk » Mon Apr 26, 2010 7:24 pm

I think you may all be missing the most important part here.
From the photo, it looks as though you embedded the schrader up to the threads. ie: it looks like you sunk it into the epoxy too far. When you screw in the pump, how far does it go? Can you tighten it all the way down to the epoxy, or does it stop short? If you are able to tighten it all the way down to the epoxy, then you sunk it in too far, and need to start over. If not, then you have an entirely different problem, and I am at a loss.
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Unread postAuthor: Gun Freak » Mon Apr 26, 2010 7:33 pm

Oh yeah good catch, Lentamentalisk. That is surely the problem... the pump head cannot get on far enough. You're gonna have to rebuild this.
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Unread postAuthor: theBOOM » Mon Apr 26, 2010 9:29 pm

I guess so, the problem is that my pump has the T type thing, where you push down on the lever and this creates the seal which allows air to go in. I'm gonna see if I can get this to work with the thread-on schrader pump heads, if not I'll try to get rid of the epoxy covering the threads, somehow. :?

EDIT. Chinerrz do you have any idea where I can get those type of pump heads for the schrader? (cheap if possible)
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Unread postAuthor: chinnerz » Tue Apr 27, 2010 1:37 am

well being an aus based spudder i would just head down to bunnings (where i was yesterday) to to compressor fittings, parts, and tool isle (where i went yesterday) there was only 2 types there, the quick connect (metal, actually grips the threads with a claw offering a good fit) and this other type i have never seen before... it looks like a ball on a shaft from the side, it would seem that you simply "hold" this fill valve over the schrader when filling...

some ideas came to me while i was writing this out....\
what if you made an adapter which fit over your schrader, and offered extra thread (however the pin would not be depressed....) unless! you got one of those $2.00 bike pumps with the threaded attachment on it and used that to attach to the schrader on your gun to another schrader or something of that description.

but then i got to thinking... why dont you just buy that $2.00 pump and use the threaded attachment from it...
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Unread postAuthor: jackssmirkingrevenge » Tue Apr 27, 2010 1:47 am

Good to see some cast epoxy :)

I woulsd recommend this type of shock pump, cheap and the head allows you to independently depress the schrader valve stem.
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Unread postAuthor: Crna Legija » Tue Apr 27, 2010 2:35 am

the screw on type of connector thats on my shock pump only threads on 1/4 the way if you get a thread on one it will work they have a pin in the middle that will push the schrader valve one.
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Unread postAuthor: chinnerz » Tue Apr 27, 2010 4:02 am

quick question. when does a pump become a shock pump??
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Unread postAuthor: jackssmirkingrevenge » Tue Apr 27, 2010 4:07 am

It's called a "shock pump" because it's meant for topping up mountainbike shock absorbers, meaning it will typically have a much lower stroke volume than a pump meant for filling tyres, but will be capable of filling to much higher pressures in the 300-400 psi range.
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Unread postAuthor: chinnerz » Tue Apr 27, 2010 6:20 am

ahh i understand now!! shock pump... shock absorbers... i get it :D what about those pumps with a massive stroke which only need one stroke to fill a cannon??
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Unread postAuthor: Crna Legija » Tue Apr 27, 2010 6:28 am

they are track pumps and stirrup pump but don't fill cannons in one stroke unless it desinged for one cannon like store bought air rifle most still use more than one
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