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 70 users online :: 4 registered, 0 hidden and 66 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

Unread postAuthor: Sergeant Dotson » Sun Apr 13, 2008 5:15 pm

How small should the holes be? Also considering that I'm using felt, couldn't the air pass through the felt?
  • 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 5:19 pm

I drill mine 1/32nds". Why felt, sounds like it will wear easy, most builders use duct tape and lube it up.
  • 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 5:20 pm

Actually, I've seen some on other sites like YouTube that have some with felt that hold up quite nice.

P.S.
Since my piston is smaller than most of yours, how big should it be?
  • 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 5:26 pm

The piston and cylinder it slides in should be matched. It don't matter if it's .50" or 10". As long as it don't tilt/jam or fit so tight it wont slide. It should have a slight drag when you push it with your hand.
  • 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: SpudFarm » Sun Apr 13, 2008 5:32 pm

not much to say the diagram says it all.

ask if you don't understand (Crowley did not understand)
  • 0

Attachments
piston diagram2.jpg
read and look closely
piston diagram2.jpg (20.87 KiB) Viewed 256 times
"Made in France"
- A spud gun insurance.
User avatar
SpudFarm
Donating Member
Donating Member
 
Posts: 2563
Joined: Sat Nov 04, 2006 9:39 am
Location: Norway Trondheim area
Reputation: 0

Unread postAuthor: Sergeant Dotson » Sun Apr 13, 2008 6:32 pm

Crowley did confuse me,lol. But I still don't get it, why none of them I make work. I just wish I could know what I was doing wrong.

BTW
Sorry, but I don't get the diagram.........
  • 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 6:37 pm

When you slide your piston with your hand, what does it feel like? Is it real easy to move, or is it hard to move?
  • 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

Sponsored

Sponsor
 


Unread postAuthor: Sergeant Dotson » Sun Apr 13, 2008 6:52 pm

Well, it's relatively easy.
  • 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 6:56 pm

Air should pass by it then. I'd like to see some pics of the piston and inside the cylinder and end cap. It would make it easier to help you.
  • 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 6:59 pm

Here she blows.... sorry for the bad picture quality, I'll turn off flash next time.
  • 0

Attachments
IMG_1023.jpg
Piston..
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 7:30 pm

Looks like it's got some rough edges, how about the cylinder it slides in.
  • 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 10:49 pm

spudfarm wrote:not much to say the diagram says it all.

ask if you don't understand (Crowley did not understand)

What the hell is your problem dude? I didn't understand my ass, i've probably had more piston experience then you. Members even recommend me as a good guy to talk to for building a first piston.

Oh and I do understand, more then you. You don't understand many things, refer to the bottom of this post.

You just wanted a damn sticky and had no clue what to do to get one. Anyone can make a diagram of a piston, that does not mean it should be a sticky.

Sergeant Dotson wrote: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.

Don't worry about it, we're progressing here :)

So just want to get a few things straight...

1) The piston housing, i.e where the piston travels, is the 1" metal chamber?

2)If you answered 'yes' to the above, It definitely has no lip or seam? Is the inside of the pipe rough?


Personally I highly recommend you sleeve the pipe, it will cost you piss-all and make things a helluva lot easier and probably will increase performance from the smoothness of the PVC pipe compared to the roughness of the metal.

All you have to do is cut a length of PVC that will reach to the barrel inside the chamber. Then find some doweling that fits, if not sand some that will. Doweling sands very easily, it'll only take a few minutes.

Then glue a neoprene sealing face onto the front of the piston, either attach a bumper or make on to suppress the impact once it opens. Lube the piston up (you are using lube right?) and then stick it inside and I see no reason why it shouldn't work.

Some trouble shooting tips:

1) Have you used a lubricant?

2) How well is the fit? Can it be pushed forward and back with your finger?
If you turn the chamber upside down with the piston inside... Does much light escape around the sides of the piston?

3) Is the seat (barrel) perfectly flat?

4) Is there area of the sealing face unexposed to the barrel when it seals?

5) Are you using enough initial pressure with enough flow to get it to seal? Mine seals with 10psi from a compressor, but my previous one only sealed at 60psi+

6) Is the sealing face clean and even? Is it made from a non-porus and suitable material?

7) Do you have minimal pilot volume?

8) Is your pilot valve adequate? Technically you could exhaust it with a schrader, but that requires some skill.

9) Do you have o-rings? If yes, do you have a very very small equalization hole?

It took two o-rings to get my piston to seal and require a equalization hole. O-ring grooves are incredibly easy to make when using wooden dowel as a piston.

Any questions, feel free to ask.


Also, spudfarm looks like he didn't understand your diagram.

You still don't get it, everyone knows how to make a piston, but in reality there are some difficulties. A diagram does not work.

Anyone can name the key components of a piston and put one together. But you can't have ONE diagram for ALL pistons. You simply don't understand, I don't know why.

Pistons are very different from one another, that's why one piston doesn't work for every piston.

Also it'd be very hard getting a disk designed piston to work in a co-axial without some support.
  • 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 » Tue Apr 15, 2008 2:39 pm

I'm sure spudfarm did not mean to offend you. And here are some pics of my NEW piston. It is made of wood, felt, a rubber washer and a rubber piece I found. I also pust some silicone around it to help the seal.
  • 0

Attachments
IMG_1028.jpg
Whole piston. You can see the equilzation cut down the side.
IMG_1027.jpg
Here is a look at the bottom angle. You can see at the top, the bottom of the equilization cut.
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: Blitz » Tue Apr 15, 2008 2:52 pm

Cool, it kinda resembles a pill bottle in that last photo. What kind of wood did you use for the piston material?
  • 0

User avatar
Blitz
Colonel
Colonel
 
Posts: 621
Joined: Sat Apr 07, 2007 1:48 am
Location: West Chicago, IL
Reputation: 0

Unread postAuthor: Sergeant Dotson » Tue Apr 15, 2008 3:05 pm

I used dowel rod, its about 3/4 inch. :P
  • 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

PreviousNext

Return to Pneumatic Cannon Discussion

Who is online

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

Reputation System ©'