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 46 users online :: 4 registered, 0 hidden and 42 guests


Most users ever online was 218 on Wed Dec 07, 2016 6:58 pm

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

Sticky Piston

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

Sticky Piston

Unread postAuthor: daberno123 » Fri May 16, 2008 4:11 pm

Today I took out my newly completed piston gun to test. I had tested the valve before, using a 1" modded sprinkler as a pilot, and thought it worked becasue of the loud noise it made when piloted.

However, after loading in a potato and squeezing the blowgun, no potato left the barrel.

It seems that my piston is sticking to the barrel, and all air in the chamber (40" of 2" PVC) is leaving via the sprinkler.

The specs on my piston valve are 1.5" porting housed in a 2" tee. The 1.5" pipe extends halfway into the tee.
I have two 1.25" caps as a piston with a sealing face bolted on using a .25" nipple and cap.
The sealing face is three layers of neoprene washers.
The piston is wrapped in a few layers of duct tape for a better fit and lubricated with white lithium grease so it slides easily.
It is piloted with a 1" sprinkler and pilot volume measures approximately 6 cu. inches.

Anyone have any ideas on why this is happening, and how I can fix it?
Any help is much appreciated.
  • 0

User avatar
daberno123
Colonel
Colonel
 
Posts: 594
Joined: Mon Nov 19, 2007 5:56 pm
Location: Ohio
Reputation: 0

Unread postAuthor: brogdenlaxmiddie » Fri May 16, 2008 4:21 pm

put some grease on it... thats what I would do... maybe some white lithium grease... put the grease on the sealing face ( if thats where u think its sticking)
  • 0


brogdenlaxmiddie
Colonel
Colonel
 
Posts: 562
Joined: Sun Jul 22, 2007 2:19 pm
Country: United States (us)
Reputation: 0

Unread postAuthor: daberno123 » Fri May 16, 2008 4:22 pm

I already did. Its in my above post.

Any other ideas?
  • 0

User avatar
daberno123
Colonel
Colonel
 
Posts: 594
Joined: Mon Nov 19, 2007 5:56 pm
Location: Ohio
Reputation: 0

Unread postAuthor: SpudFarm » Fri May 16, 2008 4:24 pm

hmm is your piston thin? mabe there is a gap from the chamber to the pilot side via behind the piston :D
  • 0

"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: daberno123 » Fri May 16, 2008 4:28 pm

If by thin you mean short in length, then I don't think so, but how short would be too short? The piston rests in a section of pipe and I don't think there are any gaps.
  • 0

User avatar
daberno123
Colonel
Colonel
 
Posts: 594
Joined: Mon Nov 19, 2007 5:56 pm
Location: Ohio
Reputation: 0

Unread postAuthor: jrrdw » Fri May 16, 2008 4:28 pm

Can you post some pics of it if you can. With the greese on it the duct tape shouldn't be causeing any problems. How loose does the piston fit? Any chance it is tipping and jamming? Is the barrel half way through the tee?
  • 0

Last edited by jrrdw on Sun May 18, 2008 4:49 pm, edited 1 time in total.
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 » Fri May 16, 2008 4:33 pm

daberno123 wrote:If by thin you mean short in length, then I don't think so, but how short would be too short? The piston rests in a section of pipe and I don't think there are any gaps.


my valve it completely sealet behind the "gap" in the back of the tee. (equalizion holes (?) )

hard to explain so i make some crappy diagrams..

Edit: the diagram are in (ask)
  • 0

Attachments
piston(148).jpg
down left is yours and the one above is what you can do and the other one is how i do it
"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

Sponsored

Sponsor
 


Unread postAuthor: STHORNE » Fri May 16, 2008 5:01 pm

jrrdw wrote:brogdenlaxmiddie, I should delete your post but I'll leave it for the embarresment factor! Reread daberno123 post, then reread yours and read them very carefully. I think you will figure out what I'm talking about.


lol, now you're just being mean jrrdw... :? Ease up on him....he's only human lol.

Due to my slow typing brogdenlaxmiddle had edited and reposted the correction I did not see that not seeing the edit, lead me to post the above mentioned, that now makes no sense....... :oops: sorry.
  • 0

Forum Rules - follow them or else!
“Happiness is the meaning and the purpose of life, the whole aim and end of human existence”
User avatar
STHORNE
Donating Member
Donating Member
 
Posts: 1208
Joined: Wed Feb 14, 2007 7:50 pm
Location: Kewaunee, Wisconsin
Reputation: 0

Unread postAuthor: SpudFarm » Fri May 16, 2008 5:15 pm

HAHA STHORNE! the fish thing make me rofl :D
  • 0

"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: jrrdw » Fri May 16, 2008 5:21 pm

Keep on topic guys, the next off topic post gets deleted with out notice!
  • 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: bigbob12345 » Fri May 16, 2008 5:41 pm

:lol:
My post did get deleted
Well there, my point is proven if you got the opportunity to read it.

But back on topic(so this post doesnt get deleted too)
Check to see if there is any sticky part of the duct tape on the outside(I probably didnt word that very well)
I had the same problem with my first piston and it was solved by adding the duct tape cleanlyer(yes I know that isnt a word).
And how tight is your piston?
  • 0

User avatar
bigbob12345
Major General
Major General
 
Posts: 1516
Joined: Sat Dec 01, 2007 9:13 am
Location: Mercer Island,Washington
Reputation: 0

Unread postAuthor: jrrdw » Fri May 16, 2008 5:52 pm

bigbob12345 wrote::lol:
My post did get deleted
Well there, my point is proven if you got the opportunity to read it.



Hey Bob --
Moderator relations:
Moderators may deem a post inappropriate at any time, for any reason, and may delete such posts without warning.
A moderator may move an incorrectly placed post. If a post/thread appears to be gone, please check your recent topics (listed in your profile) to see if it was moved.
If you question a moderator's decision, please contact the moderator via e-mail. If you have a valid objection, the decision may be overturned. Public flaming of the moderators rarely has a positive effect.
Angering the moderators/admins is HAZARDOUS TO YOUR ACCOUNT'S HEALTH! Do so at your own risk.
These rules may not be complete. Intentional exploitation of loopholes may result in new rules.
  • 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: daberno123 » Fri May 16, 2008 8:15 pm

Thanks for the diagram spudfarm. I took apart the valve and my piston is like the top left one, not the bottom left. It seems to have proper equilization holes. I tested it by blowing behind the piston. The air slowly leaked through, not in a rush like in the bottom left one.

Here are the pics jrrdw asked for
BTW, jrrdw, thanks for keeping this thread on topic for me.

This is the whole valve. I am fully aware of the massive pilot volume and there is no need to tell me about it.

Image

Piston in the housing

Image

The porting, halfway into the tee

Image

The piston itself

Image

Another picture of the piston, showing how tight a fit it is. I noticed the gash in it, but it doesn't seem to be affecting its travel at all. The piston moves easily with the push of my figure.

Image
  • 0

User avatar
daberno123
Colonel
Colonel
 
Posts: 594
Joined: Mon Nov 19, 2007 5:56 pm
Location: Ohio
Reputation: 0

Unread postAuthor: jrrdw » Sat May 17, 2008 6:37 am

BTW, jrrdw, thanks for keeping this thread on topic for me.


Your welcome.

I see a wrinkle/bulge in the duct tape. I would use a razor blade and slice it up the middle, lay it flat and trim off the essex tape. That will eliminate the possibility of that hanging it up. I see the gash half way/3rd of the way around the circumference of the piston, that is a sign of tilt type jamming. If the gash ran long ways then I wouldn't worry about it.

I also see the side clearance from piston to cylinder, a bit much in my opinion. Try another layer of tape and leave about 1/32nds of a inch gap in between the tape ends to act as a equalization hole. See what happens, keep us up to date please.
  • 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 » Sat May 17, 2008 8:17 am

good looking, i am agree with jrrdw here.. to much gap and some sort of jamming.

do you have the tools/time to make two simple o-ring grooves in it?
i wouls have taken the time to use the dremel tool to make two grooves. one at the front and one at the back.

mabe you can try to make a piston like the one on the diagram but add a neoprene washer longer back to?

first you have to try to make the piston fit so tight you feel a slight restistance (?) when you push it. more tape!
  • 0

Attachments
piston diagram.jpg
don't know if you care but it is worth it if you can't get yours to work
piston diagram.jpg (3.16 KiB) Viewed 528 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

Next

Return to Pneumatic Cannon Discussion

Who is online

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

Reputation System ©'