Build A Net Gun

Step 6 Bend Launcher Arms

In this step we will build a bending jig, and use it to bend four launcher arms to a specific angle. Make sure annotations are turned on when viewing the video.

• Launcher arm supplies

4 13" lengths of 1/2" pipe
2 1/2" PVC caps DO NOT PRIME OR GLUE THEM
Sand, at least two cups worth
Heat gun, propane torch or candle
Wood scrap and 3 2" screws to make bending jig
Leather gloves

Assembly

• Choose a launcher tube angle. A 17 or 19 degree angle will give you longer range but you may need the high performance tractors. A 21 or 23 degree angle will give you quicker opening shorter range netting, a safer bet if you are going to use soda bottle tractors. Choose and print out one of the PDF templates below. They should be printed in landscape mode on 8 1/2" by 11" paper at 100% scale.
• Build bending jig. My example bending jig is built on a scrap of 2x4 wood. Hold the template to the surface and put a screw in the pivot position Fig 1. Hold one of the arms against the pivot screw and sink screw #2 using the edge of the pipe as a guide Fig 2. Again, with the pipe held against the pivot screw, sink screw #3 using the pipe edge as a guide Fig 3.
• Cut four 13" lengths of 1/2" pipe, these are the launcher arms. Measure and mark, with permanent marker, 3" in from one end of each arm. This mark, the pivot mark, will indicate where to heat the pipe for bending, and indicate the point to line up with the pivot screw of the bending jig.
• Bend the launcher arms. Tap in place, but DO NOT GLUE, a 1/2" cap on end of the arm. Fill pipe with sand, and tamp to get as tightly packed as possible Fig 4. Fill the second 1/2" cap half full with sand and tap on the open end of the arm. The sand keeps the pipe from kinking. With both caps on the pipe the sand shouldn't slosh when shaken, if it does, add more sand. Put on leather gloves and heat arm as locally as possible on the pivot mark. Rotate the pipe rapidly for even heating and to prevent blistering the pipe. The arm is ready for bending when it will sag under its own weight held horizontally. Align pivot mark with pivot screw, the remaining short length should be captured by screw #2, immediately bend longer length of pipe over and lodge against screw #3. Allow to cool on the jig, if PVC is removed while it is still warm it will begin to straighten and lose the correct angle. Once PVC is room temp, remove from jig, remove both caps, and pour out the sand. The heating can also be accomplished with a candle, have a look at robert's instructable step #3. Both tk4717 and ome33 had good results with the candle technique.

• Repeat for the remaining three arms.

Comments

[tk4717]

okay, so I don't have a heat gun, and I don't see much of a need to buy one (likely wouldn't use it for anything other than this project) who thinks heating the launchers over a flat top stove would be a terrible idea?

[crispyjones]

The heat gun I used was from Harbor Freight, I've seen them on sale as low as $9. I think using your stove would be difficult, the heat would not be concentrated in one area. This instructable has a technique using a candle that would probably work great.

[ome33]

that candle works perfectly......its less work than the heat gun and i didnt even need to fill it up with sand

[crispyjones]

Thanks for the feedback, I've updated to include reference to the candle technique in the relevant sections.

[deerfishgoat]

hey if i dont have sand what else could i use? Would water work?

[crispyjones]

Water might work. Be careful, I think if the water gets too hot and expands it will blow off a cap. Then you would be dealing with a flying cap and hot water.

[ome33]

ok if we were to use water could we tape the caps on to avoid this expanding issue

[crispyjones]

If the water expands, there is nothing you can do to contain the hydraulic force.

[pingpongplaya911]

which angle did you use? a 17 or 19?

[crispyjones]

I've built a 17,19 and a 23. The 23 was my first go, and used soda bottle tractors.

[Pkranger88]

Why did you decide to cut and glue versus heat and bend? I would think that would be better for longevity.

[crispyjones]

I am not sure what you are asking. I use both methods, most of the gun is cut lengths of PVC glued together except for the launcher arms. They are heated and then bent.

[Pkranger88]

Sorry, my bad. I was skimming through and it looked like you had cut and glued the launcher arms rather than heating them and bending. But it turns out you did. I'm definitely gonna make one of these.

[pingpongplaya911]

k thanks which one do you think would work better? the soda bottle tractors or the PVC ones? and you should make some more vids on shootin the net gun at people!!

[crispyjones]

The PVC ones definitely work better, a little more work, but worth it.

[pingpongplaya911]

ok thanks

[tj12367]

does the net you order come with the things on the corners?

[crispyjones]

The net you order is just net, nothing else. See step 8 and step 9 for details on how to make it work with the net gun.

[footbagboi]

yeah it does. it has everything the pic has

[tk4717]

thanks, the candle worked like a charm! Anyone who doesn't have a heat gun - don't go buying one unless you'll use it otherwise... just buy a candle!