Picture of Easy PVC Pistons + Simple Airgun
Pistons are useful for many things in today's world.  For example, internal combustion engines that run our cars use pistons.  Pistons can also be used for hydraulics, pneumatics, pumps, and other devices of all shapes and sizes.  The possibile uses for pistons is endless.  However, it is very difficult if not impossible to make a perfectly sealed piston for your everyday projects.  In this Instructable I will show the process I used to make perfectly sealed pistons for PVC pipes, and how I used a piston to make a simple airgun.

A video of the airgun can be found here: http://www.youtube.com/watch?v=WGaR2vzxUu8
I had a lot of difficulty getting the video to embed properly, even though I have not before.  If anyone has a tip, let me know!
Webster's Definition of "piston": a sliding piece moved by or moving against fluid pressure which usually consists of a short cylindrical body fitting within a cylindrical chamber or vessel along which it moves back and forth
See source here: http://www.merriam-webster.com/dictionary/piston

Here's an overview of what will be explained in the following steps:
  • Step 1:  Materials Needed
  • Step 2: The Build: The Secret to the Perfect Piston
  • Step 3: The Build: Piston Pictures
  • Step 4: Simple Airgun Theory of Operation
  • Step 5: The Build: Simple Airgun
  • Step 6: Conclusion
Mo0k9 months ago

By the way: http://www.instructables.com/id/Potato-AirGun/

fozzy13 (author)  Mo0k9 months ago
Same concept. Thanks for sharing!
ilpug4 years ago
well done. ive always wondered about how to make good pistons with out messing around with o-rings. there we go. i might use this idea in an upcoming project... so sad i missed this years Launch It! challenge (and last years, and so on)

well done. i recommend shooting potato plugs or marshmallows.
fozzy13 (author)  ilpug4 years ago
Thanks!! I've struggled with the O-ring problem as well, which is a big part of what prompted this project. I could easily shoot potato plugs with this gun as-is, but I'd have to make a different barrel to shoot marshmallows.

Thanks for commenting!! : )
Nice. Btw, i have a question and a fix for your marshmallow thing.

Q-Do you know something else i can use instead of the foam rubber.

C-Maybe you can get one of those bellish-shaped reducers, and a smaller diameter of PVC. Use the PVC cement with those. Then when u want to use it you can just put it on, like an attachment.
fozzy13 (author)  LiftAndLove3 years ago
In answer to your question, there's a lot of things you could use instead of foam rubber. Regular riveter Sugru would network good ones.the foam rubber just made it way easier to get an airtight seal. Your solution to the marshmallow issue is a good one, I can't see any issues either other than maybe scratching the paint.

thanks for commenting!! : )
ilpug fozzy134 years ago
i am almost done making a rife based on this concept, and will probably have it done in time for the Challenge! i will of course site you as the inspiration for the seal design.
fozzy13 (author)  ilpug4 years ago
That sounds great!! I'd love to see the finished project. Feel free to post a link to your project here as well : ).
ilpug fozzy134 years ago
Here you go! I'm afraid it is really sloppy because i had to use a terrible camera that would just not cooperate. anyway, you can still understand it.


here is also a picture of the finished gun
potato rifle 152.jpg
fozzy13 (author)  ilpug4 years ago
Awesome!! The pictures are actually pretty good considering the camera used. It looks like a fun project, and thanks for mentioning me in the Instructable : )
ilpug fozzy134 years ago
no problem.
ViperSniper4 years ago
i want to make a DiY nerf gun for a competition. my qeustion is will i be able to use this inside the nerf gun or not?

P.S. sorry for my poor english
fozzy13 (author)  ViperSniper4 years ago
You would definately be able to use a piston design like this one to build a nerf gun, since it can be scaled up or down to any size.

Thanks for the comment!
boomboy1234 years ago
could you use nerfs
fozzy13 (author)  boomboy1234 years ago
As projectiles? Absolutely! Just as long as the barrel is the correct diameter.

Thanks for commenting! : )
tictaclad4 years ago
where the nipples do i get foam rubber?????
fozzy13 (author)  tictaclad4 years ago
I found mine at the local craft store. You should be able to find it at craft/hobby stores like Michael's or Hobby Lobby.
whats the texture like as ive never used the stuff?
fozzy13 (author)  tictaclad4 years ago
That's actually pretty hard to describe. It's sort of like a sponge, but with holes so small you can't tell that they're there? It's soft, light, somewhat squishy..
kebmoore4 years ago
This looks like a simple, elegant way to create a seal. Have you done any tests to see how much pressure the foam seal can hold? I have been holding off on a PVC project because I need to find the right O-rings. If you haven't tried higher pressures, I might invest some time and experiment with this.
fozzy13 (author)  kebmoore4 years ago
Thanks!! I have not done any tests with higher pressures, although I would really like to. If anything, high pressure seems like it would be the downfall of this method.

Thanks for commenting! This has been entered into the Launch It! Contest by the way : )..
kill-a-watt4 years ago
fozzy13 (author)  kill-a-watt4 years ago
Thanks : ).. I copied and pasted the embed code from youtube like I always do and it didn't work for some reason. Did you do anything differently?

Thanks for reading and commenting : )
no, that's exactly what I did. maybe it works in comments only?
fozzy13 (author)  kill-a-watt4 years ago
Hmm. That's interesting, I'll have to try it again. Thanks!
Devrimm4 years ago

Well, to make my water pump may take a bit long time. I am a farmer and we are living the middle of the summer here in Turkey. I have alot to do now, but winter time is good for instructables.

Devrimm4 years ago

Yes ! Thank you for the way to make it.
I'll use the same system for my water pump now !
Thank you !
fozzy13 (author)  Devrimm4 years ago
Excellent. When it is done, post pictures of the finished project if you can! Thanks for commenting! : )
Awesome gun!
fozzy13 (author)  Kaptain Kool4 years ago
Thanks! Thanks for commenting : )