Before you begin be aware that this project uses PVC pipe in an application it is explicitly not intended for. PVC is meant for water, not pressurized air or other gases. The problem is not the pressure, this project uses pressures less than half the working pressure of any PVC component, but the failure mode when pressurized by gas. If the PVC is compromised, by dropping, impact, or other means, it shatters into sharp pieces that are ejected by the pressurized gas. An excellent discussion and demonstration here, make sure to watch the video through to the end.

Nearly all of these items can be picked up at your local home improvement retailer. It is probably worth buying a full 10' length of 1/2" pipe, for all the other sizes see if you can buy shorter lengths or scrap. Alternatively, get some friends together, share the costs of the full length pipes, and build a lot of net guns. The tire valves are available at auto parts stores. The net is addressed in detail in the next step.

SUPPLIES

All PVC fittings are slip fit unless otherwise noted

All PVC pipe and fittings must be SCH-40 (SCHedule 40) unless otherwise noted

All PVC pipe should have a PSI rating of 200 or greater, absolutely no cell core ABS DWV pipe

Pressure chamber partsFig 1

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, prefer a .453" as it corresponds to the readily available 7/16" drill bit

optional 1 pressure gauge

**There are two standard size automotive valve stems, one for a rim hole sized .453" the other .625". These two sizes correspond to fractional drill bit sizes of 29/64" and 5/8" respectively, the much more common 7/16" bit can be substituted in place of the less common 29/64". Additionally, most common drill indexes stop at 7/16" or 1/2" and do not contain the larger 5/8" bit.

Trigger valve partsFig 2

1 Orbit Model 57461 1" sprinkler valve

1 Blow gun similar to this

1 1/4" NPT hex nipple, like this

Bending jig

3 2"(ish) wood screws

Wood scrap for base, a 16" length of 2x4 should work fine

Launcher sectionFig 3

4 13" lengths of 1/2" pipe

1 1/2" cross

2 1/2" tee

4 1/2" street elbows

4 1-1/2" pieces of 1/2" pipe (coupler joiners)

1 1-1/2" pipe 9" long

1 1-1/2" coupler

**1 1-1/2" to 1/2" reducing bushings

** 1 1" MPT to 1/2" slip

1 nickel

** these transitions usually can't be made with one adapter, just make sure the starting and ending dimensions are correct.

Net

Memphis Net and Twine sku# 263 1lb minimum order is enough to make 7-8 nets

OR a substitute net computed using the net math spreadsheet and instructions in step 2

Nylon mason's twine (#15 or smaller), kite string, or some other thin durable rope

4 per net 16-20oz carbonated soda bottles

4 per net zip ties > 4" long

Hot glue/silicone/wax to pour in bottles to add weight

Optional additional items needed for high performance net tractors

4 per net 3/4" couplers

4 per net 3/4" caps

4 per net 8" lengths of SDR-21(Class 200) 3/4" thinwall PVC note: regular 3/4" SCH40 will NOT work!

4 per net 12" lengths of non-adhesive 1" ID foam pipe insulation. Pipe insulation is generally sold in 6' lengths.

Consumables

PVC pipe cement and primer

PVC safe pipe joint compound (pipe dope) such as this

Teflon tape

Sand, at least two cups worth (for bending the launcher arms)

2 1/2" pvc caps (for bending launcher arms, not part of gun)

Epoxy for modifying sprinkler valve

Thread locker (Loctite)

Tools & Safety

Saw, for cutting PVC pipe

Heat gun, propane torch, or candle for bending PVC

Drill

3/16" and 7/16" (or 5/8" see the **note in the pressure chamber section) drill bits

Tape measure

Utility knife

Dremel tool, or similar, with a sanding drum

Wrench for 1/4" npt hex nipple

Large adjustable wrench or channel-lock pliers, for tightening the trigger valve

A compressor or pump capable of attaching to a Schrader tire valve and attaining at least 80 psi

Safety glasses

Leather gloves