My CPH concept

[Drenchenator]

CPVC is usually smaller than PVC at the same size. I used 1/2" rings of CPVC in a 1/2" schedule 40 PVC pump. 1/2" CPVC can almost fit within 1/2" schedule 40 PVC; you only gotta sand it a bit to get it to fit.

CPVC can take heat better than regular PVC from what I know. That's why they make it. I don't know why they make it smaller though.

[Silence]

Yep, your pump is what I was thinking of.

To some extent it may be easier to justify sticking to the advertised size than sticking to tradition. It's really PVC that makes no sense in terms of size. Maybe that's due to the early manufacturing processes, or matching 12 gauge or another pre-existing size, or something...I'm not sure. For example, paintball barrels are 12 gauge because when the hobby started, it was easier and more convenient to procure 12 gauge barrels than custom ones.

[JLspacemarine]

Okay, thanks for the clarifications!

Actually, my only worry about using 1/2 inch CPVC is the result on the pump volume. I plan to have a PC capacity of at least 1000mL, which involves an increased amount of pumps compared to stock water guns. Am I going to have an astronomical number of pumps with 1/2 CPVC beeing the pump shaft?

[Silence]

It's not going to drastically increase the number of pumps over, say, 1/2" PVC. The diameters are already rather close. If need be you could use 3/4" CPVC, but that would probably be an even nastier change.

You may have more trouble with discovering a new material combination for a seal than with the number of pumps. I don't know of any CPVC pumps that have been made, so you'll have to experiment with sizes on your own. That's not too difficult in practice, though.

Good luck with the build!

[Ben]

Finding the right sized O-ring might be a problem as SilentGuy said, but remember that O-rings stretch so if you have one that's close you can usually get it to seal perfectly with a little work cutting a knotch in wood or metal.

One thing to remember when pumping is that with a CPS and a large pressure chamber, you should have rather long shot time. So pumping should be less urgent than it would be with smaller pressure chambers. You can keep the pressure chamber full until it needs to be used again, and even if you're ambushed or something, you'll still probably have more water in your pressure chamber than they will.

Another thing to consider is that regardless of how many pumps you have to do, the amount of energy expended will be approximately the same, so the number of pumps doesn't matter unless it's so much as to take an excessive amount of time to pump because you're moving as fast as you can. So even if the diameters are very different (and they're within 0.03 inches) there won't be a real difference in energy expended.

[Drenchenator]

One thing to remember when pumping is that with a CPS and a large pressure chamber, you should have rather long shot time.

This is exactly what I thought when I build my CPS gun. I used a 1/16" nozzle to get 40 seconds of about 1 oz/s flow. I only pumped it 30 times.

As long as you keep the pump long, you shouldn't have to pump it as much. My pump pumped 60 mL, so 30 pumps put 1800 mL in the chamber. I didn't consider that much of a problem. If you go by a similar philosophy, 1000 mL really isn't that much.

[JLspacemarine]

*Building in progress*

I've finished building the pump out of CPVC. With the correct o-rings and some duct tape I managed to make it work with a wooden stick. Unfortunately, even if the pump shaft is more than one feet long, it has a volume between 30mL and 40mL, which isn't much for a homemade. At least it's on par with regular CPS super soakers...

And most of all, it works!

[Silence]

Sounds good. How much trial and error did you have to do? Were the O-ring sizes similar to what you guess regular PVC would use?

Thanks for the update.

[Drenchenator]

At worst you'll have to pump the gun a lot, which isn't too bad. The gun's power should make up for any problems with pumping, I suppose.

I'm also interested in the O-ring sizes. Do you have any pictures of the build so far or are you waiting until it's done?

[JLspacemarine]

Originally Posted by SilentGuy

How much trial and error did you have to do? Were the O-ring sizes similar to what you guess regular PVC would use?

It haven't been too hard build. I bought two O-rings of different sizes that I thought they would fit the best(having a piece of CPVC at the store to compare) and fortunately one of the two rings was the right size to use. Actually, I don't remember the size....


^ The handle comes from a fake cps1000, at least cheap copies can be usefull for something.




^The O-rings are pretty thin so I've used two for the best seal possible. The duct tape improves stability and act as a stopper.

More updates to come.

[Silence]

Ooh, pretty pictures . If you don't mind me asking, where did you take them? I've only seen tile like that in stores, schools, and public places, never in houses or apartments. Weird.

It seems like trial and error is still the best option. That looks more like electrical tape than duct tape to me (no sarcasm), but I guess that's another vote for duct tape. I've been meaning to follow Duxburian's suggestion on that, as electrical tape can slide off if the wood is wet and there's a lot of pressure.

[JLspacemarine]

After assembling some sections to preview the overall design and the building process, I've made some changes to the current design :

- The PC casing will fit over the tee fitting for a cleaner and stronger result.

- The first check valve will be placed vertically in place of the current pipe handle. Now the handle is a check valve.

- I have bought all the parts needed to do the trigger mechanism (as well as taking some pictures(coming soon)). Actually, the wire will be attached directly from the trigger to the valve and it will be placed the other side of the trigger part, between the pump rod and the second check valve. Instead of bending the wire to navigate the corner of the PC case, I'll just drill holes in the casing itself to make it reach the valve in a more straight way. That's possible without disturbing the area where the bladder will expand.

- The original gun for my SC Powerpak has been useless since its replacement for a homemade equivalent. So I think it is possible to reuse it's rotating nozzle selector on my CPH. I've thought about how it would be attached and it would work wonderfully. Actually, I'm still debating whether or not to do this. What do you guys think about it?

Originally Posted by SilentGuy

Ooh, pretty pictures . If you don't mind me asking, where did you take them? I've only seen tile like that in stores, schools, and public places, never in houses or apartments. Weird.

There's a part of my house's basement which is covered with these tiles. It's true that they aren't very common in houses. At least their neutral color is good for pictures.

[Drenchenator]

Nice use of parts with that handle! Certainly beats a PVC pipe like on mine!

A rotating nozzle selector is definitely worth the effort. No futzing around with end caps, which is a big plus. The only problem would be aligning it all correctly and holding everything together, which isn't too hard I must say. I'd do it.

[Silence]

If you've done the new layout and a check valve grip works, good for you. The check valve on my APH was way too long in the end.

Reusing a commercial nozzle selector should work well.

[Ben]

I was considering reusing the nozzle selector from my CPS 2700 actually. Ever since I "repaired" it by replacing the nozzle valve with a ball valve I stopped using the nozzle selector. You just reminded me. I don't suppose it would be hard to attach it permanently to PVC pipe.