https://www.youtube.com/watch?v=q508d3k9518

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
CleCollins
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Joined: Mon Mar 14, 2016 3:16 pm

Mon Mar 14, 2016 3:53 pm

I recently joined so bear with me here. I watched this fellow make this cannon for potatoes and I am using it as a confetti cannon. The info was weak and I would like to add to all those that have tried this and have had minimal luck. Understand that I am writing this for those with no "lathe on hand". I am an marine engineer.
This is an awesome cannon. The key items: #1 look inside the 3" pipe and make sure it is smooth. I got a rough piece so inspect the pipe before you spend. #2 The time consuming part will be the piston and its' seat (the end of the 2" barrel). These must be near perfect. The piston pieces need to be as parallel to each other as possible and the barrel must be cut near perfect. Once your piston is done, cut a piece of sandpaper to fit in it. Use a tiny drop of super glue (middle) to hold it to the piston, we will remove that later. Use the piston with the sandpaper and lap the end of the barrel. Mark the end of the barrel with a sharpy and start lapping carefully, lifting and looking at the sharpy mark. Once the mark is totally gone, you should be ok. Remove the paper with a little acetone. Now here is the tricky part. If your flat rubber packing is not very flexible, you will need to do the following. I took some 1/16" (or near) spongy tool drawer lining and cut that to fit the piston. I then took some 1/64" flat rubber packing and glued that to the lining. I glued that to the piston. Now, remember the drawer lining is porous so you must seal around the edge of the lining with super glue to keep the air from migrating under the seal and blowing out the rubber. One last thing. The less surface area on the seal at the end of the barrel, the better the seal will be. I used a regular old bastard metal file around the barrel to reduce the area in about half. Take your time.

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Last edited by jrrdw on Tue Mar 15, 2016 8:05 am, edited 1 time in total.
Reason: Embedded video.