CPH help please

Guides and discussions about building water blasters and other water warfare devices such as water balloon launchers.
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the oncoming storm
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Re: CPH help please

Post by the oncoming storm » Thu Apr 05, 2012 9:07 pm

Almost ready to build the gun just need to figure out pumps. My 1/2 dowel won't hug the wall of my 1/2 pvc any ideas.
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Re: CPH help please

Post by mr. dude » Fri Apr 06, 2012 3:20 pm

It doesn't need to, as long as the o-ring(s) does/do.

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Re: CPH help please

Post by the oncoming storm » Tue Apr 10, 2012 9:27 pm

My hornet broke and i want use the trigger on the "devastator" any ideas on how to attach the trigger to the gun ?


also how do I add/make a sling
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Re: CPH help please

Post by atvan » Wed Apr 11, 2012 5:00 pm

I doubt the hornet's trigger has enough flow for a CPH.

A sling should be easy. Just pu zip ties around some horizontal piping, and then attach a strap to that.
DX wrote:In the neanderthal days of K-modding, people would lop off the whole PRV
Well, not that much soakage.
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Re: CPH help please

Post by the oncoming storm » Thu Apr 12, 2012 4:57 pm

I can't get my o ring to stay on the dowel any ideas? All so avian I will use the trader not the ball valve
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Re: CPH help please

Post by atvan » Thu Apr 12, 2012 5:52 pm

I don't thonk that would work. There have been many trigger attempts in the past. 1 worked well.

Did you cut a groove in the dowel?
DX wrote:In the neanderthal days of K-modding, people would lop off the whole PRV
Well, not that much soakage.
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Re: CPH help please

Post by the oncoming storm » Fri Apr 13, 2012 5:05 pm

Yes and it still didn't stay in place

Oh my jontes to the resivware keep leaking air when i blow into it
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Re: CPH help please

Post by mr. dude » Mon Apr 16, 2012 10:47 am

If the o-ring won't go on despite your best efforts, it's probably too big. You can stretch a small o-ring to bigger size, it's a lot tougher to shrink an o-ring though.

Also, CA_99 has a problem with wooden dowel+o ring pumps, but I'll let him cover that.


As for leaky reservoir, just wrap some electrical tape around the joints, should hold well enough.

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Re: CPH help please

Post by Andrew » Tue May 01, 2012 12:59 pm

There are a few ways to make a strap/sling. Some are outlined on this thread from sscentral, and on this page from the wiki. As mentioned in the wiki article, you can use cable ties instead of the packaging strap things.

As for the pump, go with a smaller diameter (but obviously thicker) o-ring, or (if you're still having problems) add some form of retainer to the pump either side of the o-ring (plastic pipe or electrical PVC tape will do). Even better, use a smaller o-ring and add retainers. The retainer will guide the pump and should help the seal aswell. Take a look at Drenchenator's pump guide to get an idea.

If you want to try and make a trigger feel free, but you'll have to find some way of effectively closing the valve after every shot, and getting the wire to open the valve fully will be hard aswell. For help on triggers look to JLspacemarine's CAR homemade (also an example of o-ring retainers made from electrical tape).

As for the leak, it depends on what you used to connect the reservoir in the first place.

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Re: CPH help please

Post by the oncoming storm » Fri May 04, 2012 3:12 pm

Need to get the last 1/2" of dowel out but it won't move any ideas?
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Re: CPH help please

Post by Andrew » Fri May 04, 2012 4:32 pm

I'm, guessing you mean that the o-ring has jammed the pump rod dowel into the pump housing. If you can get some sort of lubricant into the pump housing by the jammed area that should make it easier to pull out (don't use Vaseline or anything else petroleum based, unless you completely clean out the pump area afterwards. It weakens latex rubber, i.e your PC!). If all else fails, you could just lop off the last 1/2" of PVC pipe, it's not that much extra pump length really.

It may (stress the MAY) be possible, if it's stuck because the o-ring has come out of the groove, to remove the dowel by pushing it further into the pump housing. It may sound counter intuitive, but if your REAALLY careful and take it slowly, you should be able to get the o-ring back into it's groove. You should then be able to slowly pull the pump rod out again. This method will still need lubrication to work, otherwise it will get stuck in exactly the same way as before.

Only do this if all else fails, and if you really don't want to cut the pump shorter. You can probably tell if you make even the slightest error, you could find the pump rod stuck even further into the pump housing.

EDIT: spelling errors (not counting REAALLY). Which is odd given I have a browser spell checker. :oo:
Last edited by Andrew on Fri May 11, 2012 7:24 am, edited 1 time in total.

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Re: CPH help please

Post by the oncoming storm » Thu May 10, 2012 9:16 pm

I learned that the hard way it is 3" inside
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Re: CPH help please

Post by Andrew » Fri May 11, 2012 7:34 am

:oo: I'm guessing you cut the pump shorter then. If 3" is still inside the pump housing, I'd be less inclined to cut the pump shorter. 1/2" less pump won't make much difference, but 3" less means a fair bit of pump volume less as well. This does all depend on how long your pump is anyway, and how short a pump you are happy to live with (I personally like a homemade pump stroke which is just a bit longer than I can reach, so I don't pull the pump rod out if I get a bit carried away :goofy: ). It also depends on whether you've made the pump removable so you can put a new pump housing on the blaster after you've retrieved the pump rod. Although it's probably too late, I prefer to test the pump rod in a spare piece of pipe first, just in case it doesn't fit/work/jam properly.

Have you tried the other methods?

If you can even just get the pump rod out, you should be able to get to the o-ring with a bent coat hanger or something (just don't scratch the inside surface of the pump housing!!!).

Anyway, good luck! and hopefully you'll get it to work. :)

EDIT: I'm assuming you already know, but just in case, and for the benefit of those searching the net for guides homemade blasters (it's how I found SSC), remember you'll need some form of check valve in the reservoir so it doesn't implode when you start pumping! (unless you're just going to put one or more holes in the cap, in which case don't turn it upside down if the holes are any larger than 1mm!) :cool:

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Re: CPH help please

Post by the oncoming storm » Thu May 31, 2012 12:42 pm

I need to mount a 2L bottle for the resivware and the pump is still stuck.
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Re: CPH help please

Post by atvan » Thu May 31, 2012 1:36 pm

A 2L is likely much too small to male a decent res.
DX wrote:In the neanderthal days of K-modding, people would lop off the whole PRV
Well, not that much soakage.
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Re: CPH help please

Post by Andrew » Thu May 31, 2012 3:03 pm

atvan wrote:A 2L is likely much too small to make a decent res.
Depends how big your PC is, but (generally speaking) yes, 2l is small for a reservoir, especially in a homemade (some PC's are 2l!). It's not the worst thing to use though, especially if you plan to have more 2l bottles in reserve, and screw them on when you're res is empty (probably after every full PC shot :goofy: ). It's not a bad starting place for a res though, as long as you're not too trigger happy!

If you do use a 2l bottle, you are going to have to find some way of letting air into the reservoir as you pump (or it will implode). Nothing dangerous, it just sucks, and makes it harder to pump (you're basically trying to make a vacuum in the bottle, so it just crushes itself under the air pressure around it, but at the same time is trying to suck air in through the pump. The check valve stops this from happening but it still makes it harder to pump.). There are many ways to do this:
  • Make a few holes in the bottle - it leaks.
  • Put a check valve in the bottle - in the cap maybe? The plastic body of the bottle isn't really rigid enough to support it.
  • Put a check valve on a separate piece of pipe which also leads into the bottle - may let air into the pump and therefore PC (not good) or it turns you're CPH into an Orca (not good [again]).
As for mounting the bottle, that really depends on how you want to mount it. Do you want to put a hole in the bottom of the bottle, and stick a pipe in there (lets you use the screw cap for filling) or do you want the bottle to screw onto the blaster (at which point you'd have to make a hole in the bottom of the bottle anyway to let air in). Or maybe even a hole in the side of the bottle so the reservoir is more linear (like an XP 75 or SS 50)?

As for the pump, if you've tried my suggestions, then post some pics up (aim the camera inside the pump rod to get as clear a look at the problem as possible).

I can't really see any reason for the pump to be stuck other than the o-ring coming out of it's groove. Can you take the pump off your CPH, or is it solvent welded onto the blaster already? If you can take it off, it should make getting the pump rod out much easier, and prevent any damage to the blaster when carefully applying brute force. The pump in my homemade got stuck a few times when I first tried putting the pump together. I had to pull quite hard on the pump rod to get it out (copper can take a bit more abuse than PVC though so be careful!!!). Lubrication is key. Nothing petroleum based obviously.

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Re: CPH help please

Post by the oncoming storm » Tue Jun 05, 2012 4:40 pm

First of all the size this is a Asaught Rifle

I want to screw it on but my 2L's are threaded backwards

My dad says I should cut off the PVC for pump and just put on more
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Re: CPH help please

Post by Andrew » Wed Jun 06, 2012 5:38 am

You could use the cap that came with the 2l bottle (put a hole in the cap and use a male threaded connector with a nut and washer to secure it in the cap, or just glue it in). You would still need some way to let air into the bottle as you pump, without drawing this air into the pump system itself. Perhaps you could cut a hole in the bottom of the bottle and glue in a small check valve.

You could also (to avoid cutting into the bottle) have something like this:
Image

The yellow intake (a straw or some small vinyl hose?) lets air into the bottle, without letting air into the pump or PC. The PVC tee connects to the bottle's cap (you can unscrew the bottle itself) and the check valve is just one of those small ones that people use in aquariums.

If you do just cut off the pump pipe, you can't let your new pump's o-ring go that far into the blaster. It will wear the o-ring out much quicker if it has to keep passing over a rough surface, or sudden change in pipe. Not a big problem, just put a handle on the end of the pump rod, and make sure the handle hits the PVC pipe before the o-ring hits the join. You will need to sleeve the pipe though (you probably know that). If you can't get the current pump rod out, and you don't mind doing this, there is nothing wrong with it. It's just one extra place for potential leaks.

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Re: CPH help please

Post by atvan » Wed Jun 06, 2012 6:07 pm

Uh, Andrew, the end of your post is in the wrong discussion. That would be the next topic down. :goofy:
DX wrote:In the neanderthal days of K-modding, people would lop off the whole PRV
Well, not that much soakage.
Beware the Purple

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Re: CPH help please

Post by Andrew » Thu Jun 07, 2012 6:40 am

atvan wrote:Uh, Andrew, the end of your post is in the wrong discussion. That would be the next topic down. :goofy:
If you mean about the bottle, something similar could be used for the drink maker thread, but I did mean to post it here. This doesn't need to hold pressure (other than hydrostatic head) so the straw doesn't have to be as secure as for the drink maker.

I will admit these two topics are getting very similar. :|

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