Step 2: Net Procurement and Math

I ordered my net from the Memphis Net & Twine Company. If you have your own favorite gill net vendor, you can probably order an identical item from them. I have NO financial ties to MN&T other than being a satisfied purchaser of their retail products.

Here is the link to the product page on the MN&T website. Below is the exact info from my order information page, shipping is not included in the price. One pound of this net (minimum order) will make 7 or possibly 8, 9-1/2 foot square nets.
Sku: 263
Description: 3 in. sq. mesh, 12 ft. deep
Qty: 1lb
Price: $12.65

If you would like to try an alternate net part number please read the Alternate Net Substitution section below.

Optional Net Math Section
You may have noticed that the catalog description lists the net as 12 feet deep while I have claimed it is 9-1/2 feet square, why the difference? Let us first deal with a hypothetical net that has 3" mesh and is 3 meshes deep. You might think 3 x 3 equals a 9 inch deep net, but that would be incorrect. Visualize the meshes as diamonds stacked point to point and NOT squares stacked like bricks. Reference Fig 1 and it becomes apparent that the depth of our hypothetical net is nearly 12-3/4 inches. To extend this example to MN&T sku# 263, 27 x 4.24 equals 114.48 inches, divide by 12 and we get 9.55 feet deep. So where does MN&T get the 12 foot depth figure? They are building a certain amount of droop, when used in a fishing application the diamonds will be longer vertically than they are wide.

I have included a spreadsheet that will allow you to enter different figures to see what size net you will end up with, and how many nets you will get from a pound of that particular net. If the spreadsheet returns a zero for waste material, you may want to subtract one net from the total expected. The default numbers in the spreadsheet are for MN&T sku #272.

Alternate Net Substitution
I will use MN&T catalog and part numbers in this example, but as long as you know the correct variables, any net vendor should work. Using the spreadsheet is important, if you don't own MS excel, consider downloading OpenOffice. An excellent free MS office replacement that will allow you to view and edit the Net Math spreadsheet.

Please consult Fig 2 or have the spreadsheet open for this example. The top section of the spreadsheet contains a section called Mesh Count Estimator. This will help you calculate the mesh count you need to reach a desired net size. In this example I have entered 3.5 (3-1/2" mesh) in the Mesh size cell and 9.5 in the Desired depth cell. This should closely match the sku #263 net's overall size but with a 3-1/2" mesh instead of 3". The computed result, 23.03 appears in the mesh count cell. As fractional net meshes don't exist, just round to the closest integer, 23 in this case. Next, we will browse through the MN&T catalog for a 3-1/2" mesh net 23 meshes deep.

Go to the multifilament net section of the MN&T web catalog, then select #208 twine size and browse through the 3-1/2" mesh part numbers to find a net closest to the 23 mesh count. Part number 272 fits our specification perfectly.

Now enter all the information from the 272 page into the yellow cells on the Enter line of the net properties section of the spreadsheet. The Square depth cell tells us this net will be 9.43' square. This is also the spacing for the knots of your spreader string in step 9. The Knot cut point shows we need to count 46 knots and then cut between knot 46 and 47, the Cut length cell tells us knot 46 should fall at 161" on stretched netting. We can also assume that because the overall weight of the 272 net is slightly less than the 263 net, it should fit fine in the net holder.

I would advise waiting to build the net holder part of the launcher section if you try any radically different mesh, twine, or overall net sizes. Once you have the net constructed, fold it up and make sure you have the correct size PVC holder.

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!
The new show "The White Rabbit Project" used your design on an episode. They used it to take down drones.
Thanks for the heads up. Can't wait for the big royalty check ;)
<p>Fantastic! I didn't have this in time to catch a run away peacock, but I will next time. It made me so mad that he was 10 feet away from me and the only thing I could do was hope he don't fly up into the oak trees, which he did of course. Took three days for him to finally come back home. Not going through that again, Thank you for the design, no way I could afford $1000 for one</p>
If you caught a peacock or hen with this net gun I would definitely add the video or picture to my instructable!
<p>Hey Guys, I myself am attempting to build this to assist with rescuing geese and ducks for the rescue i volunteer at. I have the build complete but at the moment im having an issue with pressure. When attempting to fill with air, its just coming straight out and not staying in the chamber behind the valve....im almost certain i followed your instructions step by step. The only difference is I am using the model 57661 and not the 57461. If you think that will make a difference I will order one.</p>
<p>I can say that this thing is a blessing. I have finally gotten it together and fired my few test rounds and it WORKS. I will be sure to post pics/videos of the first bird rescue i do.</p>
<p>silicone spray is a great lube for this gun</p>
<p>and how bout the thing that goes over the pipe to use to fire?</p>
<p>Hey, buddy. You're a genius :D</p>
<p>We build lots of launchers for paintball, airsoft and MilSim, and are not allowed to use any with PVC air chambers, or those green orbit valves, anymore (just changed the rules on valves this year)- the had some of those shatter too. Probably was dropped, but they were quick to ban them.<br>We use CO2, argon, or oxygen tanks, they can had pretty cheap, are indestructable and rated for over 3,000+ psi burst. They need drilled and tapped, but it's all metal and really safe. With a carbon fiber valve, we can go to 150-175 PSI. Double the range and still be safe. Most compressors only go to around 110 PSI anyhow.<br>We also have push button, and other parts.</p>
Thanks for ideas FrankC19. Do you have any links to the stuff you build, and I am interested in the carbon fiber valve.<br>
<p>This was designed beautifully! Definitely something I'll have to try!</p><p>It would be even more awesome if you had an automatic wind-up of the net, so if you miss, you can just hit a button, a motor and string would pull the net back, replace the tractors, charge the tank, and you're ready to go!</p>
<p>normally this top weekly email stuff is really dumb.. this is a something i have wanted for years. i might put time into somthing like this!</p>
<p>Wow, this is splendid. Just what I need to capture neighbors' or gvt. quad-copters over my yard.</p>
<p>I can use it to catch my drone when it refuses to come home&hellip;...</p>
<p>What application did/do you use to make your cad drawings/models?</p>
<p>Something like this could be of interest to law enforcement. Thanks for the Instructable.</p>
<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>
<p>There is always fiberglass cloth impregnated with resin. That is how plastic pressure tanks are made. just saying.</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>
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>@ 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!
<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>

About This Instructable




More by crispyjones:A Timing Belt Belt Viva Pinata! (make a Sherbat) iPad nano 
Add instructable to: