Instructables.com - Build A Net Gun

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.
Image Notes
1. 3" mesh with hypotenuse X.
2. Pythagorean theorem, solving for length of hypotenuse X.
3. Hypotenuse multiplied by number of meshes deep.
4. Result is depth if all meshes are square. In the netgun application they are, as
the net tractors pull equally at all four corners.
File Downloads
Net Math.xls (76 KB)
[NOTE: When saving, if you see .tmp as the file ext, rename it to 'Net Math.xls']
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
Assembly
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.
http://www.instructables.com/id/Build-A-Net-Gun/