Build A Net Gun

Step 4 Build The Trigger Valve Assembly

In this step we will modify an Orbit Model 57461 1" jar top sprinkler valve, making it a pneumatically actuated trigger valve. I found this particular model to have a number of advantages. It is the cheapest 1" valve I've found. The air valve is installed in the center of the cap allowing easy orientation of the trigger. Finally, the "jar top" construction makes it extremely easy to work on. Here is a link to a page devoted to modifying this exact valve, I left out the safety ball valve in this design. Here is a link to a visual explanation of how the sprinkler valve works.

Trigger Valve Supplies
1 Orbit Model 57461 1" sprinkler valve
1 Blow gun or similar
1 1/4" NPT pipe/hex nipple, like this
Epoxy
Teflon tape
Wrenches
Dremel or drill
Threadlocker

Assembly

• Remove solenoid and bleed screw, they will not be needed Fig 1. Save the solenoid for future diabolical inventions.
• Disassemble valve by unscrewing the "jar" ring. Be careful, as under the top is a spring under tension.
• Cut, grind, or drill out the center of the top, make sure to leave enough plastic to thread the 1/4" NPT fitting into Fig 2. Grind or cut down the lip of material around the center hole to the level of the ribs Figs 3 & 4. This will allow you to get the fitting deep and tight.
• Use the 1/4" NPT fitting as a tap for cutting threads into the hole you just made, try to keep it as perpendicular as possible Fig 5.
• Once you have the threads cut, put Teflon tape on one end of the fitting and thread that into the blow gun Fig 6. Apply some thread locker to the other end of the fitting and tighten the whole assembly into the valve top.
• You are now ready to epoxy three places. A little dab in the bleed screw hole in the top, a little dab in the bleed hole at the valve outlet, and a good bit of epoxy around bottom and top of the brass fitting Figs 7 & 8. Try and leave the wrench flats of the fitting exposed and epoxy free in case you need to remove the blow gun at some point.
• Let the epoxy dry and then reassemble valve. The lever side of the valve should be underneath the outlet of the valve. Make the securing ring is as tight as possible.

Comments

[dremeldude]

if you wanted the trigger to be more accessible you could substitute the nipple for two barbs and hose.

[Iwanna b]

Your link to a blowgun sent me to a website, but there are many choices there, which one is the one I should buy?

[crispyjones]

I changed the link to go where it used to, thanks for catching that.  Unfortunately, it looks like that model isn't available mail order from Harbor Freight.  It is a very common style of blow gun, I've seen it at auto parts stores, hardware stores, even Walmart.

[baughmanmark]

I did everything you said to do with the Trigger Valve System but when I put air inside the chamber is leaks out of from that hooks to the tennis ball attachment and also when I press the blow gun it does nothing. What am I doing wrong?

[baughmanmark]

Never mind about my question. I put the wrong end towards the pressure chamber (the arrows were pointing toword the pressure chamber).

[crispyjones]

First make sure the flow arrow on the valve is pointing in the direction of the air flow, back of the arrow towards tank, pointy end towards outlet. Next, put some air in the pressure chamber and see exactly where it is leaking from. If it is leaking out of the small "nipple" in the center of the outlet (step 4, fig 7) than you need to seal that off with some more epoxy. If it is leaking out of the outlet (and not the nipple) than it is likely the diaphragm is not seating. This can happen if PVC chips get stuck in there, just disassemble the valve and make sure the seating surface is clean.

I went through some similar issues earlier this link *might* (direct link to comments seems flakey) take you there. If not, go back to the May 31, 2009 comment string in Step 5.

If none of this helps, post the things you tried and I will see what I can do.  Good luck.

[Kantor]

would heavy duty liquid nails be a good epoxy??

[crispyjones]

I doubt it. I know they sell some different versions of the product, but the ones I've seen don't look suitable.

[Kantor]

so what would work?

[crispyjones]

Use the two part epoxy that comes in the double syringe type applicator. It is sold by many manufacturers, I have used different brands with similar results. I think I used Loctite brand last time, but I am not 100% sure.

[Kantor]

i just so happen to have about half a syringe of that stuff laying around,thanks for the help

[ducktapeman55]

in figure 7 on the left, do i need to epoxy the gap below the hole? i epoxied the hole and tested it out but it seemed to leak

[crispyjones]

The gap below that hole doesn't lead anywhere.  That hole is connected to the thin metal pipe that serves as the guide rod for the diaphragm.  I would pressurized the valve and put it underwater, bubbles will make it obvious where the leak is coming from.  If the water test confirms you have a leak there, just fill the metal pipe with epoxy and you will be sealing the same passageway.

[iTinkers]

Is there any reason you could not use a solenoid valve for the trigger rather than the sprinkler valve? I'm interested in making this, but it seems it'd be much simpler to use a NC solenoid valve. Is there a practical reason not to? I'm looking at a few online that are 1/4 NPT, 12V. 0-150PSI. Says they are "fast acting" even though the exact times are unknown. Seems they'd be perfect for this project and much simpler to use. Am I missing something though?

[crispyjones]

I am pretty sure you won't get the necessary air flow through a 1/4" NPT orifice. You could skip step 4 and leave the sprinkler valve unmodified with solenoid in place. Check step 7 in this instructable for some more detail on a trigger circuit. The valve probably won't open as fast as one modified with a blow gun, but it might be acceptable.

[GianniMora]

can i use j.b. weld

[crispyjones]

I used a two part epoxy so it would flow into the holes in the valve, and around the threads of the coupler. J-B weld doesn't flow, so you will have to force it somehow, possibly leaving voids were air can escape.

[GianniMora]

ok thx

[mazingbrainiac]

http://www.homedepot.com/h_d1/N-5yc1vZ1xr5/R-100051587/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053, and the http://www.lowes.com/lowes/lkn?action=productDetail&productId=23026-147-CP-100&lpage=none are the only 1 sprinkler valves i could find, which would wok better? thnx

[crispyjones]

I don't have personal experience with either one, but spudfiles has a writeup on the cp-100. It looks like the net gun that jm838 built uses a cp-100.

[ome33]

I was going to use a ball valve instead of a sprinkler valve thus eliminating the need for a blow gun.............how would i install this

[crispyjones]

If you buy a 1" threaded ball valve, just substitute it in place of the sprinkler valve in Step 5. Install so that it is easy for you to open it quickly.

[gjjones125]

I don't understand step 4 are you actually cutting threads, as in making your own? How do you do that? Sorry I am building it but I'm kind of a noob (although I have tons of experience with PVC).

[crispyjones]

Yes, you use the metal fitting to cut threads in the plastic. The hardest part is getting the first turn into the plastic. As you tighten the fitting (with a wrench or socket) it will cut its own threads into the plastic.

[gjjones125]

Ok thanks

[tk4717]

The only Sprinkler valve I could find at home depot was Orbit model 57101. It's still 1" but is slightly different. Can this valve still be used, if so, what mods do I have to make to these instructions?

[tk4717]

never mind... I monkeyd it into working - if anyone else has the same issue, let me know and I'll give you some hints.

[bricez28]

i have the 57101 as well, howd you get it to work?

[crispyjones]

Check to forums over at spudfiles. They have tons of info.

[qwertyboy]

no! don't throw away that perfectly good solenoid! put it in your junk box that way if you need a solenoid, you have one.

[crispyjones]

You are right, updated step 4.

[treinengek]

why don't you use the solenoid as trigger its powerful enough for the pressure and a circuit can be made

[cowboy93]

i have access to a welder so would it be better to make the pressure chamber out of metal pipe then out of pvc

[crispyjones]

The weight increase would depend on the type of pipe you used. If you just used off the shelf black pipe, it would be pretty heavy, other types might weigh less. You will still need to end up with 1" thread to go into the sprinkler valve, as well as have a hole for the tire valve.

[cowboy93]

alright thank you

[phamthephong100]

Where did you get the pressed air to fill the chamber?

[Lance Mt.]

A compresspor

[efrenba]

Hi, What's the function of the sprinkler valve, it lets the air to pass completely or only a fraction through it?

[crispyjones]

The function of the sprinkler valve is to release as much of the air as quickly as possible into the launcher arms. Here is a good visual description of how they work, just replace the solenoid valve with a blow gun, vent.

[Didrtan]

does the blow gun need the rubber tip?