APH Concept

[cantab]

Any bike pump will have an intake port, an intake check valve, and the output. I don't think they need an outlet check valve because that's in the bike tyre.

If you can find and block the air intake then it might work - though long term I'd be worried about rusting.

[SEAL]

Yeah alright. I'll have to buy some more parts though.

I haven't been doing anymore construction because of the all-star game yesterday. Today I'm going to do a lot more.

[JuchTurtles]

A bike pump won't work in a pressurized chamber design, only in a pressurized reservoir because in that instance, in a gun like SC2, air and water are seperated. You need a pump with a better seal and an air pump will just push out water and you won't build pressure (except for maybe in your onboard reservoir - NOT a good idea).

You're going to need a new pump, that's all I've got to say. Besides that, not bad design, though an onboard isn't always desirable due to weight and unsteadiness.

[SEAL]

UPDATE: I did some more work on it today. I didn't glue anything because it's raining out. I will do the gluing tomorrow.

I took a whole bunch of pictures, here they are:
I found out something. I took apart the pump, and found an O-ring in there instead of a normal plunger thing. In this case, can I actually use this pump?
Here is a pic.


And here is a close-up of the O-ring.


Here we have a pic of the front of the blaster, with the PC's on top. (The PC's aren't glued. That's why they look so tall.)


And now, these pictures show how the tee on the top of the handle slips on.

Here is what it would look like underneath the tee.


This is the tee. It's 1" across, and 3/4" down. So the handle itself is going to be 3/4".


This pic shows the tee sliding over the pipe.


And here is the tee in place. It fits quite snugly over the 3/4 inch tee.


Here is the handle in place. This also shows the other tee on the bottom of the handle, it slides over the bike pump.


Here is a layout of all the parts.(Except the ones I'm missing.)
The front part.


The middle part.


The end part with the reservoir. I'm not sure if I'm going to use it yet though.


There you have it. I am missing a couple of parts, so I will be going to Lowes in a few minutes.
Bye for now.

[cantab]

Is the plastic around the o-ring fully hollow, opening into the inside of the metal tube? If so, block it up with epoxy. Then your pump should work.

If it works, and works well, you'd be to my knowledge the first person to use a modified bike pump for an APH. And if it works well it could become the new de-facto standard. APH pumps have always been a nightmare.

[Silence]

Yes, your initial check valve configuration was fine (remember to point the valves in the correct direction ). To go into more detail, when pumping air, a problem appears at higher pressures: the air compresses and just sits in the space before the check valve. Water does not compress and must go to some place with volume to spare (the pressure chamber).

cantab's right, it should be fairly easy to fix the pump, now that you have it open. If you're interested in how it works (originally), Scavenger posted some useful photos in this thread from WaterWarfare.com. In particular, check out the top right of this diagram. When you pull the pump out, the O-ring slides and allows air from outside to bypass it and fill up the pump tube. Those grooves are visible in the second photo from the post just above - fill them with epoxy and you'll be able to use the pump like normal.

Like cantab, I'm eager to see how well your water gun works, because bike pumps have much better seals than homemade ones and they have lots of potential. Good luck!

[zeda.beta]

Also, if the center of the pump is open, fill that in too.

[SEAL]

Hi guys. Sorry for a lack of updates, but I was busy yesterday. I did manage to fit everything together though. It just hasn't been glued.

@cantab: The plastic around the o-ring is not hollow.

@Silence: What I thought of doing, is to get a fatter o-ring and put in in place of the old one, that way it won't slide around. Or I could get a smaller o-ring, and put it next to the original. I actually tried that with a rubber band, but for some reason, it wouldn't compress air. Does that mean it could have pumped water while the rubber band was on there?

@zeda.beta: What do you mean by the center of the pump? Are you talking about the same thing that cantab was talking about? Or do you mean the front of the pump with the handle? Because that actually might be hollow. I'll check.

I'm going to resume work today. Stay tuned!

[zeda.beta]

Okay, in picture 2 of your previous post, you showed the pump.
Look at the end that has the plastic holding the o-ring.
In the middle of the plastic, there might be a hole.
If there is, fill it in with epoxy, because that is letting excess pressure out.

The attatched photo shows which end I mean, and where to look

Edit: Not sure what cantab was talking about exactly.

[cantab]

Yes, that is where I though there might be a hole.

[mysterio]

This looks to be pretty beast when its finished. i cant wait for the stats.

[SEAL]

Alright then! The blaster is almost complete. I've glued everything except the PC's. I would have glued them, but it started to rain so I couldn't. And of course the pump and reservoir aren't on yet ether. Unfortunately, my camera ran low on batteries, so I didn't get any pictures.

And no, there is no hole in there.

I'll hopefully finish it tomorrow.

[Silence]

I wouldn't trust a fat O-ring to fix the problem, not alone. If it's loose enough to slide around the lip and into position, then it's loose enough to slide once you're pumping with 15 pounds of force. Multiple O-rings may work, though. If you have multiple, then one of them may always block the route for air to get to the inlets. And finally, the rubber-band may indeed have allowed you to pump water, but it probably would be a little leaky, so you'd want something more permanent once your water gun is complete.

Anyway, there's no rush because fixing the pump should be simple and can be done later. Good luck finishing construction!

[SEAL]

Hey everyone. The entire blaster is now glued, and the only thing that needs to be done before I can fire it, is the pump. Tomorrow, I'm gonna get a bunch of o-rings and try them out.
I also added a cap onto the reservoir.

Pictures will be coming soon.

[SEAL]

I fixed the pump. It now works like a syringe blaster. I tried it with a bucket of water and it could shoot water out to about 30 feet or so. I just replaced the old o-ring with a smaller and fatter one. I am currently working on modifying the pump handle so it won't slide off. The handle originally would slide off because of the increase in resistance when I put the fat o-ring on.
(Okay, okay, I didn't explain that to well. What I meant was, since the new o-ring was put on, the pump became harder to pull. So when I tried to pull it out, the handle would slip off because of my pulling harder then the pump company intended.)

Tonight I hope to be firing it. I will take a bunch of pictures of the complete blaster and post them here. See you then!