Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 65 users online :: 4 registered, 0 hidden and 61 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

Piston Help

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
Sponsored 
  • Author
    Message

Piston Help

Unread postAuthor: Sergeant Dotson » Sun Apr 13, 2008 1:16 pm

I'm not typically the type to ask for help, but well, I need some. I just made the main construction of my first piston cannon about a week ago now. Since then, I've been tinkering around with materials but have never found something that works.

Specs:
-Chamber is made of black metal
-Chamber is 1'
-Barrel is 1/8"

Any help would be appreciated, and as always, thanks for the help.

-Sarge
  • 0

Attachments
IMG_1015.jpg
Whole gun in 2 pieces.
IMG_1016.jpg
Trigger and fill setup.
User avatar
Sergeant Dotson
Sergeant First Class
Sergeant First Class
 
Posts: 149
Joined: Mon Jan 21, 2008 5:53 pm
Location: Tennessee
Reputation: 0

Unread postAuthor: jrrdw » Sun Apr 13, 2008 1:46 pm

Do you want to know what to make the piston out of? What have you used so far? A list of what you tryed will elimanate repeats.
  • 0

When life gives you lemons...throw them back they suck!
User avatar
jrrdw
Donating Moderator
Donating Moderator
 
Posts: 6538
Joined: Wed Nov 16, 2005 5:11 pm
Location: Maryland
Country: United States (us)
Reputation: 25

Unread postAuthor: Sergeant Dotson » Sun Apr 13, 2008 1:49 pm

Well, I've tried rubber cork, wood, types of plastic caps. And yes, I do need help with what materials I need to use. :oops:
  • 0

User avatar
Sergeant Dotson
Sergeant First Class
Sergeant First Class
 
Posts: 149
Joined: Mon Jan 21, 2008 5:53 pm
Location: Tennessee
Reputation: 0

Unread postAuthor: jrrdw » Sun Apr 13, 2008 2:00 pm

Did you lube the piston? Maby the blow gun isn't piloting the chamber fast enough, try unscrewing it fast and see if it fires then. You mite be able to hold you thumb over the hole and test it that way.
  • 0

When life gives you lemons...throw them back they suck!
User avatar
jrrdw
Donating Moderator
Donating Moderator
 
Posts: 6538
Joined: Wed Nov 16, 2005 5:11 pm
Location: Maryland
Country: United States (us)
Reputation: 25

Unread postAuthor: Sergeant Dotson » Sun Apr 13, 2008 2:03 pm

I've tried all of that, I just need some kind of material that would work.
  • 0

User avatar
Sergeant Dotson
Sergeant First Class
Sergeant First Class
 
Posts: 149
Joined: Mon Jan 21, 2008 5:53 pm
Location: Tennessee
Reputation: 0

Unread postAuthor: jrrdw » Sun Apr 13, 2008 2:13 pm

Bondo <-----is a maby
Epoxy<-----talk to JSR
Wood<------thats what I use
PVC caps glued together<-----pretty much a standered build

Are you possitive air is getting past the piston into the chamber? What exactly happens when you try to fire it?
  • 0

When life gives you lemons...throw them back they suck!
User avatar
jrrdw
Donating Moderator
Donating Moderator
 
Posts: 6538
Joined: Wed Nov 16, 2005 5:11 pm
Location: Maryland
Country: United States (us)
Reputation: 25

Unread postAuthor: MrCrowley » Sun Apr 13, 2008 2:22 pm

Are you palnning on having the piston travel inside the galv chamber? Good lukc getting it to work, not only do you have to make a groove for the pipe seam, but you can never get a good fit with the galv.

The piston will hardly actuate at all because of the gap between the galv and piston. If your piston is a good fit, it wont move. You really need to sleeve the galv chamber with PVC or copper.

For a 1" chamber, 3/4" PVC with a groove cut for the seam works perfectly. That's how I made mine. I used a wooden dowel, which was easy to make o-ring grooves in with just a dremel.

http://www.spudfiles.com/forums/crowley ... 13459.html
  • 0

User avatar
MrCrowley
Moderator
Moderator
 
Posts: 10207
Joined: Fri Jun 23, 2006 10:42 pm
Location: Auckland, New Zealand
Country: New Zealand (nz)
Reputation: 4

Sponsored

Sponsor
 


Unread postAuthor: Sergeant Dotson » Sun Apr 13, 2008 2:29 pm

Well, all I know is that it is supposed to be a barrel sealing piston. And yes, i'm sure it's leaking. When I even fill this with air, it just leaks out the barrel. :(
  • 0

User avatar
Sergeant Dotson
Sergeant First Class
Sergeant First Class
 
Posts: 149
Joined: Mon Jan 21, 2008 5:53 pm
Location: Tennessee
Reputation: 0

Unread postAuthor: jrrdw » Sun Apr 13, 2008 2:47 pm

I wasn't even considering that the cylinder wasn't smooth. Yes what MrCrowley says, the piston and cylinder have to be matched. You have a few bugs to work out. You can sand down the inside of the chamber/cylinder and make a bigger piston for a nice fit. Try to get all the air leaks stopped, that helps.
  • 0

When life gives you lemons...throw them back they suck!
User avatar
jrrdw
Donating Moderator
Donating Moderator
 
Posts: 6538
Joined: Wed Nov 16, 2005 5:11 pm
Location: Maryland
Country: United States (us)
Reputation: 25

Unread postAuthor: Sergeant Dotson » Sun Apr 13, 2008 2:54 pm

I think that the sanding is unnescesary. I'm sure I can make one to fit it. I just need something to make it with. I guess I'll research some more.
  • 0

User avatar
Sergeant Dotson
Sergeant First Class
Sergeant First Class
 
Posts: 149
Joined: Mon Jan 21, 2008 5:53 pm
Location: Tennessee
Reputation: 0

Unread postAuthor: MrCrowley » Sun Apr 13, 2008 3:17 pm

Just do what I told you to do, sleeve the metal chamber with PVC or copper, then find wooden doweling at your hardware store that fits. If it's a bit off, a small amount of sanding will only take a few minutes.

Sanding is sometimes necessary.

You wanted help, and that's what I gave you. It is a good option.

It is very hard to get a piston working in a galv chamber, it's too rough, has a seam and the front is slightly tapered inwards which will leave a gap around the piston inside the chamber.
  • 0

User avatar
MrCrowley
Moderator
Moderator
 
Posts: 10207
Joined: Fri Jun 23, 2006 10:42 pm
Location: Auckland, New Zealand
Country: New Zealand (nz)
Reputation: 4

Unread postAuthor: Sergeant Dotson » Sun Apr 13, 2008 4:53 pm

Well, I'm in the process of making one of wood and using felt around it to make it fit. On the end is a rubber washer and on the outside of the barrel, I put rubber tubing that will even further help it seal against the barrel. And, MrCrowley, there is actually not a seam on the inside of my pipe and there is also not a lip on the inside. Not trying to put you on the spot, but just stating what is there.

BTW,
How snug should the piston fit in the chamber?
  • 0

User avatar
Sergeant Dotson
Sergeant First Class
Sergeant First Class
 
Posts: 149
Joined: Mon Jan 21, 2008 5:53 pm
Location: Tennessee
Reputation: 0

Unread postAuthor: jrrdw » Sun Apr 13, 2008 5:00 pm

"BTW,
How snug should the piston fit in the chamber? "

If you made equilization holes make it have a slight drag. If you don't have the holes it should fit loose enough to let air go in but not allow the piston to tilt.
  • 0

When life gives you lemons...throw them back they suck!
User avatar
jrrdw
Donating Moderator
Donating Moderator
 
Posts: 6538
Joined: Wed Nov 16, 2005 5:11 pm
Location: Maryland
Country: United States (us)
Reputation: 25

Unread postAuthor: Sergeant Dotson » Sun Apr 13, 2008 5:11 pm

Which do you think would be easier, equilization holes, or loose fitting? :?
  • 0

User avatar
Sergeant Dotson
Sergeant First Class
Sergeant First Class
 
Posts: 149
Joined: Mon Jan 21, 2008 5:53 pm
Location: Tennessee
Reputation: 0

Unread postAuthor: jrrdw » Sun Apr 13, 2008 5:13 pm

Power and relieabilty wise I like equlization holes.
  • 0

When life gives you lemons...throw them back they suck!
User avatar
jrrdw
Donating Moderator
Donating Moderator
 
Posts: 6538
Joined: Wed Nov 16, 2005 5:11 pm
Location: Maryland
Country: United States (us)
Reputation: 25

Next

Return to Pneumatic Cannon Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'