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Pnematic Mod for Rainbird CP-100 sprinkler valve

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Pnematic Mod for Rainbird CP-100 sprinkler valve

Unread postAuthor: williamfeldmann » Mon Sep 10, 2007 10:27 am

I managed to come into around a dozen of the 1 inch Rain Bird valves at an auction and since they were cheap, and frankly the only 1 inch inline valves I can find that I don't have to pay shipping and handling on where I am from, I decided to do a mod program on this particular valve.

This is the Rain Bird CP-100 valve that I will be modding. It is commonly available at most Menards. You might find it other places as well.
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Supplies I used include the valve:
#15 O-ring (can be found in the faucet repair section of any hardware store) and a 3/4 inch PVC plug for the solenoid chamber,
a 1/4 hose barb to 1/8 NPT (note the size is not what is pictured), 1/4 inch hose, blow gun and hose clamps, and 1/4 hose barb to 1/4 NPT for the blow gun.
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This pic shows the solenoid chamber and the manual bleed port opened to show where the work will be happening.
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After taking off the lid, there is a spring in-between the lid and the diaphram that is kind of small and fits in a small recess under the manual bleed port. It is this spring that limits the size of brass fitting that can be used. The following picture shows the 1/8 NPT to 1/4 hose barb sitting in the spring to show that it will fit inside. This particular fitting is somewhat difficult to find in stock. I found them in stock at Menards. Note: I used to work at Lowes while going to college, and it is a stock item for them even though they do not usually stock it. You can order a whole box of them if you plan on doing very many mods and this particular fitting will work on an ORBIT Watermaster as well. The box could have 10 to 20ish of these in it depending on the distributor for your particular Lowes store. You can also find them at http://www.mcmaster.com/.
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Using a 3/8 drill bit and drilling from the inside of the lid, drill through the manual bleed port. You want to drill from the inside of the top chamber because the little hole from the bleed port and the natural cross hairs will get you a perfectly centered hole through the manual port. Drilling from the top will be somewhat difficult to get a centered hole because the manual bleed screw/plug has a decent diameter to it and the drill bit needs something to guide it straight. turn in the fitting to thread the plastic and then thread it back in with teflon tape on it. This valve works well for this because ALL of the threads on the fitting or held in the plastic. This is much stronger than having only 1/3 or 1/2 of the threads holding.
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The above picture shows the pvc plug in place. Taking off the solenoid and looking into the chamber you will see the port leading to the top chamber of the valve is down in the corner (you can see this in the pic earlier showing the ports opened up from the top). Sticking one #15 O-ring into the solenoid chamber will cover this hole. Screwing the pcv plug in will squish this O-ring and form a air tight seal on that one port. This is nice if you reuse your valves from time to time (which I do) and would like to option of ever returning the valve to electric operation. DO NOT glue the plug in, use teflon tape. It is a zero pressure chamber it will not leak.

This picture shows the inside of the lid after the fitting has been put in. Note that the hole drilled is smaller than the recess that the spring sat in so the spring still has a good seat all around the fitting. This is why drilling from the inside of the lid is important.
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Once you have gotten the fitting in place, you can reattach the lid onto the body of the valve. Put the spring in and screw the lid back down. Rig up the blow gun as usual, using the 1/4 hose barb by 1/4 NPT fitting and teflon tape and use a hose clamp to clamp it down. The other end of the hose fits on the barb sticking out of the top of the valve, clamp this on and you have modded a very common and easy to find 1 inch sprinkler valve.
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This last picture is of my first cannon using the first valve I converted. It is a 4 inch chamber and 2 1/2 inch tennis ball barrel. GGDT says this gun is capable of 300+yards with a heavy tennis ball although all I have shot so far is normal weight balls with lower pressure. To give a point of reference, I am 6 foot 2 and the end of the barrel is difficult to see but it is in the trees behind me. I fire it over the shoulder, bazooka style, the 3 inch wye that is part of the tank sits in front of my shoulder in firing position.
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All of these pictures are available on this idex page as well here,
http://www.public.iastate.edu/~lnieman/
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Unread postAuthor: jackssmirkingrevenge » Mon Sep 10, 2007 11:43 am

Very well written and idiot proof tutorial which the newbies will appreciate :) If that's your first pneumatic then clearly don't fall into the latter category, I'm sure it will look good in the showcase.
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Unread postAuthor: silverdooty » Mon Sep 10, 2007 12:09 pm

i found that the spring would close the diaphragm prematurely leaving the chamber still pressurized. i removed it and now the chamber expels all air.
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Unread postAuthor: williamfeldmann » Mon Sep 10, 2007 12:46 pm

Jacksrevenge

Not quite new to the game, I have built more than a few smaller ball valve guns in the past but this was my first sprinkler valve gun. Boy that valve makes a big difference.

silverdooty and all

I have noticed that my valve shuts a bit early as well. However, I have not had any shut-offs prior to the ball exiting the barrel. I did not open up the tiny equalization hole in the diaphram since I charge with a bike pump. My highest pressure shot has been a 75psi shot (boy were my arms tired). I hold the trigger on the air gun till the ball fires then close it. I have had as much as 20 psi left over in the tank after these shots. I know my barrel is shorter than optimum (should be a little short of 8 feet) at 5 feet 5, but size was kicking my ass while building so using GGDT acceleration curve I went with 5-5 to get the most accel in a managable frame.

I wonder if I will need to open the equalization hole a bit to use an air tank to charge the gun (what i want to do eventually)? Any thoughts?

Also check this post for other questions on design for this gun and my next gun in planning phases right now. http://www.spudfiles.com/forums/viewtopic.php?p=117375&sid=2e3490a73c03c307b597b42215c60cbf#117375
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Unread postAuthor: singularity » Mon Sep 10, 2007 2:02 pm

you should watch out that cannon has dwv fittings on it, i wouldn't suggest going above 60psi.
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be sure to check out my <a href="http://www.spudfiles.com/forums/ak-style-airsoft-vortex-gun-t10959.html">AK Styled Vortex Gun</a> and my <a href="http://www.spudfiles.com/forums/at-4-t9627.html">AT-4 Rocket</a>

upcoming projects... finalized clip fed BBMG and ball point pen sniper
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Unread postAuthor: MrCrowley » Mon Sep 10, 2007 4:13 pm

I'll just copy my other post into here as well, but great tutorial, should help some people out.

Looks like you have a tee and a wye in there, both aren't pressure rated.

Sch.40 is referred to as the thickness of the pipe but what you need to look out for is NSF-PW XXXPSI @73F. If it has that on the pipe it's all good to use.

Not sure about you but pressure rated pipe doesn't fit DWV fittings here, so your pipe may not be rated as well.

Very kick ass gun though, I like it alot.
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Unread postAuthor: Hubb » Wed Sep 12, 2007 4:56 pm

You have remaining air in your chamber because of the size of the chamber. The thing is massive. First, try holding the trigger for a while longer (similar to a follow-up shot when shooting a firearm). This may exhaust all the gases from the chamber. If not, try making your pilot hole bigger and shortening the pilot hose. If that doesn't work, you may need a bigger valve.
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Unread postAuthor: dongfang » Thu Sep 13, 2007 3:06 pm

Hi,

Very good quality instruction and result!

I´d consider just to leave the spring in, since the remaining air probably would not contribute (assumption; should be verified) very much to performance, and replacing it requires boring pumping. But if you have a compressor...

Regards
Soren
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Unread postAuthor: williamfeldmann » Thu Sep 13, 2007 3:24 pm

I am not sure what you mean about the spring. I left the spring in.

Hubb,

I know that the chamber is huge but that is for a reason. I built this cannon as a prototype that I can play with to try future things out on. Currently I am looking at adding a breech loader to the barrel for instance. I am also turning the barrel around for an over-under tripod gun. I did originally want the gun to reach 150 psi but the dwv fittings I used negate that, but even at 75 it works for what I wanted it to do.

The extra or leftover pressure in the chamber is no big deal in fact it is nice, less pumping for the second and consecutive shots :). The valve has no problem with air flow. I am interested to see just how fast the valve is against the 1 inch Watermaster I just ordered.

See Existing Cannon Questions thread for other info on this cannon as well as the over-under tripod job I am currently working on.

http://www.spudfiles.com/forums/viewtopic,p,117374.html#117374
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Unread postAuthor: dongfang » Thu Sep 13, 2007 6:21 pm

Hi,

OK, I mean: With the spring, maybe your valve re-seals when the projectile is already near or beyond the end of the barrel. If that is the case, and if it were my gun, I would just be happy about that. It would save me from having to pump the first few bars of pressure for the next shot.

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Unread postAuthor: MrCrowley » Thu Sep 13, 2007 6:47 pm

I took the spring out my valve, no difference whats so ever. It still left some air in the chamber with and without a spring and power was similar.(I can't say the same without proof can I :P )
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Unread postAuthor: clide » Thu Sep 13, 2007 9:13 pm

MrCrowley wrote:I took the spring out my valve, no difference whats so ever. It still left some air in the chamber with and without a spring and power was similar.(I can't say the same without proof can I :P )


Somebody has measured it before. IIRC it was boogieman and it resulted in zero performance difference. I think with the spring actually had slightly higher performance, but it was within the range of error of the experiment.
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Unread postAuthor: williamfeldmann » Sat Sep 22, 2007 3:53 pm

With this program it is just as easy to leave the spring in. It isn't in the way or anything with the 1/8" fitting.

If there is no performance difference I would say leave it in, maybe it will close the valve faster and allow for faster repeat shots, well maybe not with the monster of a tank like this but you get the picture. :)
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Unread postAuthor: HaiThar » Sun Sep 23, 2007 11:52 am

Hmmm...You posted on my thread about the Jartop rainbird...Modding it would obviously be different... If the manual bleed screw or whatever is is someplace else, do you know if you still use the center and just fill in the hole for the screw or what?
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Unread postAuthor: williamfeldmann » Sun Sep 23, 2007 2:32 pm

If you are modding the Jar top valve by Rainbird that looks similar to this valve, you will notice a few subtle changes.

There is a manual bleed off port but it is off centered near the edge of the lid. The port is not a circle, but a sort of circle with a tail. This is where you will drill and tap in the brass fitting. The manual bleed port is the same size and everything as the valve pictured. Use the same 3/8" drill bit and 1/8" NPT fitting of your choice. You could choose to go straight to a blow gun if you wanted or a hose barb.

Your new fitting will not be in the center of the valve but you will see no difference in functionality or performance. Just location.

As for how I blocked off the solenoid, all 1" Rainbirds have the same size solenoid port so you will be able to stick a #15 Oring in and use a PVC plug to seal that port up. If you do this you will be able to reverse the moddification to operate electronically someday if you so choose. I am not sure if 3/4" valves have the same solenoid. It appears that the solenoids look larger on a 3/4" and might be the same part in which case this would work for smaller valves as well. I know the bleed off ports are the same size. Of course for a dollar more you can the increased flow of the 1" so just spend the buck for a lot better performance.

EDIT: spelling
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