Step 3: Build The Pressure Chamber

The pressure chamber is assembled first. It should be allowed to cure a full 24 hours before applying pressure. PVC pipe assembly is simple and is covered in other instructables as well as on youtube. A brief refresher on solvent welding PVC pipe. Use in a well ventilated area, make sure both pieces to be assembled are clean and free of burs, prime both pieces, put glue on both pieces, assemble with a twisting motion and hold for 15 seconds. For brevity's sake, solvent welding will be referred to as "gluing" PVC. The video shows how all the parts are assembled, make sure you have youtube annotation turned on.

Pressure chamber supplies
1 1" MPT (Male Pipe Thread) to 1" slip street elbow
1 1" elbow
1 2" to 1" reducer bushing
1 2" cap
1 2" coupler
1 foot of 1" pipe
Minimum 9" length of 2" pipe
1 valve stem
PVC primer and cement
Drill and 7/16" bit (or 5/8" if you purchased the larger base valve stem)
optional 1 pressure gauge

  • Drill the correct size hole in the center of the 2" cap. 7/16" for the smaller (.453" base) valve stem, or 5/8" for the larger (.625" base) valve stem. Pull the valve stem through this hole.
  • Cut a length of 2" pipe at least 9" long. Keep in mind that the longer it is the more time it will take to fill up if you are using a manual air pump.
  • Glue the 2" to 1" reducing bushing into the 2" coupler
  • Glue the 2" cap with tire valve to one end of 2" pipe. Glue the coupler to the other end.
  • Glue a short piece of 1" pipe into the bushing, glue the 1" slip elbow onto that.
  • Cut a piece of 1" pipe for the pistol grip, something between 3" and 6" should work. Glue the 1" MPT street elbow to one end of pistol grip pipe.
  • Glue assembled pistol grip pipe into 1" slip elbow on pressure chamber. Ensure that the threaded fitting aligns with the axis of the pressure chamber and doesn't point off to the right or left.
  • Optional: Drill a hole of slightly smaller diameter than the fitting of the air valve, locate the hole 3/4" into the pipe side (NOT the bushing side) of the 2" coupler. Use the air valve to cut threads into the hole, then thread back in using thread locker on the fitting.

NPT........not NPR.......typo, my bad.
Thanks for sharing, this is what makes Instructables work.
The red handle is just a 1/4 in. ball valve that was added to act as a safety (don't want any accidental discharges!!) It's in the open position in the photo. The hole to the left is where the solenoid was located. Epoxy the entire bottom of it. take out all the screws, pop off the lid gently with a screw driver, (use notch provided next to where solenoid was). Drill you hole for the 1/4 in. NPT nipple that mounts your blow gun (or a 1/4" ball valve, then blow gun- if desired). When you have the diaphram valve cover off, epoxy your threads from the nipple you inserted into the cover (without getting epoxy into the fitting) and epoxy the little bleed hole as well (small rectangular opening that leads into where the solenoid was located....not totally necessary, but why not since you have the cover off. Let sit for at least 20 min. before charging your gun with pressure. The Orbit valve model #57461 is the one in the photo. Enjoy. Thanks Crispy for the info!
Just the thing. I posted these instructions to a dog rescue site. Hoping that it might be useful in catching skittish strays
<p>I have made a version of this gun with a slightly larger pressure chamber, which runs 15mm copper pipe from the trigger mechanism. It pressurises to 100psi very easily, has no leaks, but when I fire it the tractors have a poor range. Any ideas?</p>
Cool, I'd love to see a picture. Couple basic things to check. <br><br>What kind of range are you getting? I worry less about range and focus more on how the net snaps open, there is only so far a 10' square net pulled by some PVC pipes will go. If it snaps open quickly and evenly then everything is probably good. If the net never really opens fully then you might have an issue.<br><br>With just the valve attached (unscrew the launcher section) do you get a loud bang and a bit of recoil when you pull the trigger? If not than your sprinkler valve isn't releasing air fast enough, could be on backwards, could be something jamming the diaphragm, could be a restricted trigger valve, to name a few possibilities.<br><br>If your valve is good, check your tractors. Do they slide smoothly off the launcher arms?<br><br>Good luck.<br><br>
<p>Thanks. I will post a photo &hellip; I'm getting about a 5 foot range at the moment. I'll check the things you mentioned, but do you think it could be that there isn't any pipe diameter reduction from the trigger on my version? It's 15mm all the way from the trigger. Thanks again...</p>
<p>If it is 15mm between the output of the pressure chamber to the input of the sprinkler valve, then yes, that's likely too small and the cause of the poor range. If you are just talking about 15mm launcher arms, then I am not sure that would be too small. I've only built my netgun using US spec PVC so I honestly don't know how things will behave with different materials and sizes.</p>
<p>WOWOWOWOWOWOWOW this is 1 <strong>BIG </strong>Instructable. it mustiv taken u ages!!!! by the way very cool idea </p>
<p>Would you be able to get springs strong enough to build a spring-loaded version of this - for portability?</p><p>I would be able to use a cast net in the ocean without spraining my elbow.</p><p>It can also (maybe) used to take down drones in a less police involving way than this:</p><p><a href="http://www.wdrb.com/story/29650818/hillview-man-arrested-for-shooting-down-drone-cites-right-to-privacy" rel="nofollow">http://www.wdrb.com/story/29650818/hillview-man-ar...</a></p>
Clicky link&nbsp;<a href="https://www.youtube.com/watch?v=IVO4_hUvFsc" rel="nofollow">https://www.youtube.com/watch?v=IVO4_hUvFsc</a>
<p>Here's a thought/question: Couldn't one reduce the risk of PVC shards by wrapping all of the appropriate parts with athletic tape or perhaps some other type of tape?</p><p> (e.g., http://www.amazon.com/McDavid-Oxide-10-Yard-Rolls-Athletic/dp/B003E3ZSUC)</p><p>If an impact or other event were to occur that would normally cause the pressurized PVC to shatter, I'm not sure if any reasonable number of layers of tape could actually bolster the PVC enough to help prevent that from happening...or could it? Regardless, assuming that the PVC would indeed shatter, it seems to me that even a few layers of athletic tape would help to reduce the velocity of any shrapnel, and a few more layers might even contain the shards enough to *prevent* them from becoming shrapnel entirely, much in the spirit of laminated safety glass but with the binding layer on the outside.</p><p>I like the idea of athletic tape because I have seen projects wrapped carefully in it, and it provides a sleek look and good grip. With safety as the issue at hand, though, I would rather use an ugly tape that would work better than one that is cosmetically superior but functionally inferior.</p><p>I have no specific knowledge regarding the engineering involved or the behavior of the materials in question, so all that I can do is to speculate. I would appreciate any thoughts on these questions from anyone who actually knows enough to offer more than my guesswork: (1) Is this idea feasible? (2) Is there another kind of tape (duct tape?) that might work even better than athletic tape? (3) How many layers might it take to reduce significantly the velocity of shrapnel, to prevent flying shrapnel altogether, or (if even possible) to actually strengthen the PVC enough to make it more shatter-resistant?</p><p>Great instructable, by the way! I am sorely tempted to set aside the time to make one of these.</p>
If I was going to pick a tape I would probably choose duct tape, this is based on instinct and utterly non-scientific. That being said, I've built a few iterations of these things and never used tape. The only hardening I tried was to build an all-coupler version (pictured) of the pressure chamber. Not sure if it is any safer, but it's definitely heavier. I have actually broken one unit (not the all-coupler version) under pressure, it took a 5' fall from my deck railing and hit the ground. It snapped in two at the thin handle part of the pressure chamber, no large explosion of shards. I've fixed the video link in the 1st step but here it is directly https://www.youtube.com/watch?v=IVO4_hUvFsc.<br><br>I don't really have a good answer because there isn't one. We're using a piping system not designed for gas pressure to hold a pressurized gas. Out of the gate we've violated the design specs and therefore we are on our own. If you do some experiments let us know how it turns out.<br><br>
<p>@ RDmaniac on the end of compressed air tank there is a tire stem -like on a car or bicycle tire .Use a compressor with a tire fitting to fill the tank with compressed air </p>
<p>Errrr, there is a reason PVC or CPVC (sch 40 or 60) is not used for air systems and is banned by OSHA. It can SHATTER into small shards, like a hand grenade, with no warning. The psi ratings are for LIQUID. Hate to see it do that next to someones face. Just sayin'...........</p>
<p>well now I have to build a new barrel for my air cannon to shoot a net. This is just too cool, Batman would be proud. Very impressed with the size of the net that can be fired.</p>
Which of the MANY comments and corrections of these instructions, which ones do I need to pay most attention to? I am going to make about 40 of these so I really need to know. Thanks for helping.
<p>Are you selling them? </p>
<p>Hello exex.</p><p>I plan to use them. I live in the highlands of</p><p>central Mexico. I have talked to many witnesses</p><p>who have seen pterosaurs (pterodactyls). I plan to use</p><p>the net guns to catch one(s). Seriously. John</p>
<p>Epic!!! Btw, 3/4 in cpvc (not a typo - it also hapens to be stronger) fits paintballs well. have fun!!</p>
<p>Fun to make! Going to modify to take out a pinata this May.</p>
<p>Hi, has anyone tried to make one of these using the potato gun hair spray ignition instead of compressed air? It seems like it would work. </p>
<p>I'm a bit late to the party but would like to take a few moments to heartily commend your efforts on this instructable. Your work in detailing the plans is &quot; top notch&quot; and I'm quite sure consumed a considerable amount of time, gathering data and drawing all the steps. THANK YOU. As a bird wildlife rescue and rehab volunteer, I have spent a inordinate amount of time trying to capture birds that have been compromised by fishing line and even lures embedded in them. They are injured and need help but are not diminished enough (yet) to easily catch. This net gun will be a real time saver for all that do this kind of work. Our goal is to catch 'em, fix 'em and release 'em as quickly and humanely as can be accomplished. Prolonged attempts to capture are quite stressful for them. This will help a great deal. My construction will begin today and I will be wrestling with a way to &quot;modify&quot; the net gun to utilize a tank of air that will be more suitable in the field as the refill in the field would be tough! Thanks again for your efforts</p>
<p>Hi Caddyb</p><p>i need to build this for a similar purpose - for street dog catching in India. We have literally millions in our cities and road accidents occur on an everyday basis. Catching injured dogs is very challenging as they are already very scared. </p><p>how did your build go? I will be building it from here in India, but i would like to source all the parts (except the pipes) from USA (i will be traveling for a week next week). </p><p>could you share the list of non-pipe parts you purchased and from where?</p><p>Can you be my mentor while i go through the build?</p><p>Thanks in advance!</p><p>Sandeep</p>
<p>Hi, i couldnt quite figure out the source of compressed air... can someone please explain what powers this launcher?</p>
<p>This is what i ended up with. And I'm very pleased with the outcome and the spread of the net!!!</p>
That's great, thanks for posting the pic!
This is awesome
This is awesome.
<p>Hi,</p><p>What can be used for an air source? A bike pump?</p><p>Thanks</p>
<p>Hi,</p><p>What can be used for an air source? A bike pump?</p><p>Thanks</p>
<p>I was wondering if there was a way to increase the safeness of this gun in terms of the pipes bursting from air pressure. Are there any fail-safe methods I can use to stop the pipes from bursting from the pressure, or to stop shrapnel from being sent everywhere in the event of an explosion? <br>Thanks. </p>
<p>There should be a video on how to make the net.</p>
<p>You do know that drilling a hole through a nickle is illegal. Unfortunately, I found out after I did it.</p>
<p>um... uhhh....lets see...ehhhhhh......no... can you please repeat the question?</p>
<p>i have to try this.</p>

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