T-Shirt Cannon

A couple months ago I had a little bit of extra time in my leadership class. My teacher has always wanted a T-Shirt cannon for rallies and football games, so I thought I would make him one. I made one a couple months ago, but then I broke it. The way I broke it is actually a funny story; I was shooting apples at a hornets nest to destroy the nest. Apples seal so well in the barrel that there is more kickback than I am used to. One of my shots had so much kickback that I dropped the cannon. Unfortunately, I dropped it at just the wrong angle and the handle broke. The way I had set up the handle meant that the integrity of the pressurized barrel was compromised. Being for school, I didn't want to risk my t-shirt cannon becoming a pipe bomb. I decommissioned my old one, and set out creating a new one. I documented the new and improved cannon, and that's what this instructables is.

I made this video documenting the whole build. It's a bit long, but I hope you like it. It goes hand in hand with the instructables. My idea was that you would watch it to understand how it works, but then use the instructables to get the measurements and a more accurate step by step... enjoy!

I'm not great at explaining thing, but I'll do my best.

1. You fill the cannon with air
2. inside, the pressure pushes the piston mechanism, this pushes the rubber cork into the hole, sealing the barrel
3. once the cork seals, the diy plastic one way valves opens and the entire barrel pressurizes
4. Nothing happens until you squeeze the trigger
5. Squeezing the trigger releases air from the first (smaller) chamber. The released air creates a pressure difference between the two chambers
6. the high pressure chamber (the one on the left) pushes the whole piston to the right to keep the chambers equal pressure
7. As soon as the piston moves to the right, the cork unseals
8. When the cork unseals the air can rapidly escape
9. the cannon fires

Materials:

• Filler Primer
• spray paint (2 colors)
• 3d Printing Filament
• vinyl
• acrylic
• lid of a Pringles can
• Teflon tape
• 3" abs pipe (about 1')
• 1/4"-20 threaded rod
• 2x 3/4" washers
• 2x 2" washers
• 5x 1/4"-20 nuts
• 2x 1/4" ~ 5/8" hose clamps
• 2x brass hose barb (sorry, I forgot what size. The threaded end needs to go into the air blow gun)
• 1x Air blow gun
• 10" of tubing that matches the hose barb
• schrader valve

PVC Parts (all of them are 2"):

• 1x coupler
• 1x female adapter
• 1x male threaded end cap
• 1x 2" to 3/4" adapter

Tools:

• 3d printer
• laser cutter
• vinyl cutter
• random orbital sander
• 120 grit sandpaper
• 400 grit sandpaper
• sponge
• soap
• bucket/sink with water
• pvc Primer
• pvc welder
• wood saw
• hack saw
• chisel
• heat gun

You'll need a 2' section of pvc pipe. Also, a half inch piece. The half inch piece is to prevent the piston from coming out of the cylinder. The only way to get it in the threaded female adapter is to cut a piece out of it about half an inch long.

The other pvc part is a little more complicated. Take the 2" to 3/4" adapter and cut out the sloped part. This will at as a seal against the cork at the end of the cannon. I included a sketch of how the final part should look. If I remember right, you need to cut about half an inch off of both sides of the adapter, and the part you want is in the middle.

If you want to shoot more than shirts, you will want a smaller barrel. Cut a piece of pvc about 3' long.

2" pvc makes a good barrel and 2' to 3' is a good length.

I included a gluing diagram in the images above. My main advice is to make sure the parts are lined up. Cut the pvc pipe to 11 inches. and glue the rest on, pushing it on all the way tight.

The barrel is quite easy to make. For t-shirts, you wan to cut a 2' length of 3" abs pipe. Also, you need a 2.5" piece of 2" pvc pipe. The final part is a an adapter to connect the pvc and abs. I 3d printed my own, and I recommend you do the same. It is easy to do and it looks cool. Also, I don't know you can buy that type of adapter anywhere. abs

The end cap consists of two holes. The whole for the brass fitting should be smaller than the threads so that the threads bit in and seal. The whole for the valve should be slightly larger than the threads so the threads don't engage at all. This way, the nut on the thread pulls the rubber seal tight against the pvc.

I found that by far the best way to attach the brass fitting is with a deep throat socket and a drill. This way you can spin the fitting really fast. When you spin it fast, the metal heats up and melts the pvc a little bit. This creates the best seal between the metal and the pvc, and will keep your t-shirt cannon leak free.

Cut the threaded rod to 11.5".

Cut out a piece of acrylic to keep the cork concentric with the pipe.

Cut the edge off of a Pringles can lid drill a hole in the center. Push the plastic Pringles lid into the pipe. While you do that, use a heat gun while you push so that the edges curl up. This will make a great seal.

Attach the cork to the threaded rod with nuts and washers and One end of the threaded rod should be

--nut/cork/nut/acrylic aligner/nut----------------and the other----------------nut/little washer/big washer/plastic seal/big washer/little washer/nut--

the pictures and youTube video should help...

I designed the cannon handle for a 2 inch pipe coupler. You can find my file here, on thingiverse. I printed it in PLA on my flashforge, it took about 30 hours and covered almost all of the print bed.

Finishing the Handle:

After printing the handle, it was time to finish it. I sanded the shallow slopes with the orbital sander and 120 grit so that the rough contours would fade. Then, I sprayed it with filler primer by rustoleum. If you have never used this, it is awesome. I totally recommend it, it makes 3d prints look really professional. After it dried (or cured, I'm not really sure about paint terminology) Anyways, after a while it was ready to sand. I filled my sink with water and a drop of soap. I then took a thin slice of sponge and a thin slice of 400 grit sandpaper. Using the sponge sandpaper combination to smooth the curves, I sanded the whole thing. Dipping it in water after every few sand strokes.

After wet sanding the filler primer, I had nice finish.

I painted the handle black, with some nice red grooves. I'm not going to go into depth on this, all I did was paint the whole handle black, and the masked off everything but the grooves, proceeding to paint them red.

The rest of the paint job would be easier if you didn't want a decal, I am giving this to my school, so I wanted to put the school mascot (a lion) on it. I used the school vinyl cutter to make a stencil. After painting everything black, I applied the stencil and painted the lion head red.

Push the piston into the pressurized chamber. You may have to use a thin needle to poke the flared edges into the pvc pipe. After that, compress the guard ring into the female thread. Wrap the pvc end cap in teflon tape and screw it into the female adapter. Push the hose onto the barbs and secure it in place with the hose clamps. Push the barrel into the end of the cannon body, and you're done!

Thanks for reading, I hope enjoyed it and learned something. Feel free to comment or ask any questions, I love hearing back from the community. Stay awesome.