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 49 users online :: 4 registered, 0 hidden and 45 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

piston probs :(

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 probs :(

Unread postAuthor: experament-u2 » Sat Jun 02, 2007 10:56 am

ok i know every one has problem with there pistons but mine doesn't seam to want to pull back when vented now the piston fits perfectly inside the cute and doest need orings or duck tape and seals well against the barrel and even with my light spring removed it wont work

plz help i rely want to get this gun working :(

the crappy paint below is my basic set up
  • 0

Attachments
untitled.JPG
untitled.JPG (18.31 KiB) Viewed 393 times
User avatar
experament-u2
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 469
Joined: Tue Dec 26, 2006 11:18 pm
Reputation: 0

Unread postAuthor: homedepotpro » Sat Jun 02, 2007 11:08 am

what is you pilot source and do you have large equalization holes in your piston
  • 0

User avatar
homedepotpro
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 443
Joined: Sun Nov 26, 2006 1:00 am
Reputation: 0

Unread postAuthor: spudthug » Sat Jun 02, 2007 11:11 am

do u have any equilization holes i nyour piston? i know alot about pistons now so if u could post a pic of ur piston, inside the tee,bumper,and pilot, i can probably help u
  • 0

4" piston valved cannon-half done..( i spilt my cement...)

Hybrid- 75% done. need to build propane holder and drill/tap sparkplug hole..
User avatar
spudthug
Brigadier General
Brigadier General
 
Posts: 936
Joined: Mon Feb 26, 2007 9:02 pm
Location: johnsonburg, Pa USA
Reputation: 0

Unread postAuthor: keep_it_real » Sat Jun 02, 2007 11:38 am

There needs to be air in front of the piston so it can be pushed back when piloted. By the looks of your design, you just need a smaller barrel.
  • 0


keep_it_real
Captain
Captain
 
Posts: 320
Joined: Sat Dec 23, 2006 4:41 pm
Location: Bend, Oregon
Reputation: 0

Unread postAuthor: experament-u2 » Sat Jun 02, 2007 11:52 am

my pilot source is a 1/4 ballvalve
i have a pin size equalization hole in he piston
my bumper is a old sprinkler valve spring

heres the hole piston
Image

heres a blurry picture of my piston
Image

piston inside chute (old piston)
Image
Image

the chute inside tee
Image

inside the tee
Image
  • 0

User avatar
experament-u2
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 469
Joined: Tue Dec 26, 2006 11:18 pm
Reputation: 0

Unread postAuthor: hi » Sat Jun 02, 2007 11:52 am

can you tell us that kind of tee its built into? what size the everything?
  • 0

"physics, gravity, and law enforcement are the only things that prevent me from operating at my full potential" - not sure, but i like the quote

you know you are not an engineer if you have to remind yourself "left loosy righty tighty"
User avatar
hi
Major General
Major General
 
Posts: 1619
Joined: Thu Feb 01, 2007 9:28 pm
Reputation: 0

Unread postAuthor: experament-u2 » Sat Jun 02, 2007 11:54 am

keep_it_real wrote:There needs to be air in front of the piston so it can be pushed back when piloted. By the looks of your design, you just need a smaller barrel.


im using a bit 3/4 poly pipe for my barrel and the id is allot smaller than the od

hi wrote:can you tell us that kind of tee its built into? what size the everything?


the tee is 20mm pvc and the end cap is 25mm
  • 0

Attachments
untitled.JPG
untitled.JPG (18.91 KiB) Viewed 374 times
User avatar
experament-u2
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 469
Joined: Tue Dec 26, 2006 11:18 pm
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: spudthug » Sat Jun 02, 2007 11:55 am

ur barrel isnt halfway through the tee is it? it doesnt look like it and that is ur problem..

Edit: also the sealing face of teh barrel needs to be smaller than the id of the tee so there is air to force it back
  • 0

4" piston valved cannon-half done..( i spilt my cement...)

Hybrid- 75% done. need to build propane holder and drill/tap sparkplug hole..
User avatar
spudthug
Brigadier General
Brigadier General
 
Posts: 936
Joined: Mon Feb 26, 2007 9:02 pm
Location: johnsonburg, Pa USA
Reputation: 0

Unread postAuthor: experament-u2 » Sat Jun 02, 2007 12:25 pm

spudthug wrote:ur barrel isnt halfway through the tee is it? it doesnt look like it and that is ur problem..

Edit: also the sealing face of teh barrel needs to be smaller than the id of the tee so there is air to force it back


im pretty sure the barrel dosnt need to be half way through the tee

and the sealing face of my barrel is smaller than the id of the tee
  • 0

User avatar
experament-u2
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 469
Joined: Tue Dec 26, 2006 11:18 pm
Reputation: 0

Unread postAuthor: Velocity » Sat Jun 02, 2007 12:31 pm

If your barrel is halfway through your tee, it will make it a LOT easier to seal.
  • 0

User avatar
Velocity
Brigadier General
Brigadier General
 
Posts: 1039
Joined: Tue Feb 07, 2006 5:42 pm
Reputation: 0

Unread postAuthor: keep_it_real » Sat Jun 02, 2007 12:41 pm

Do you have any air in front of the piston?

im using a bit 3/4 poly pipe for my barrel and the id is allot smaller than the od


The OD needs to be smaller also to allow for space so the piston can be pushed back.
  • 0


keep_it_real
Captain
Captain
 
Posts: 320
Joined: Sat Dec 23, 2006 4:41 pm
Location: Bend, Oregon
Reputation: 0

Unread postAuthor: experament-u2 » Sat Jun 02, 2007 12:41 pm

keep_it_real wrote:Do you have any air in front of the piston?

im using a bit 3/4 poly pipe for my barrel and the id is allot smaller than the od


The OD needs to be smaller also to allow for space so the piston can be pushed back.


oh now i under stand,
is there any way i can modify my design to allow air around the front of the piston

hears a better picture of my set up
  • 0

Attachments
piston.JPG
piston.JPG (12.41 KiB) Viewed 352 times
User avatar
experament-u2
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 469
Joined: Tue Dec 26, 2006 11:18 pm
Reputation: 0

Unread postAuthor: hi » Sat Jun 02, 2007 12:46 pm

if that is an accurate picure, then the problem is that there is no air in front of the piston to push it back. try using a tee that is a little bigger.
  • 0

"physics, gravity, and law enforcement are the only things that prevent me from operating at my full potential" - not sure, but i like the quote

you know you are not an engineer if you have to remind yourself "left loosy righty tighty"
User avatar
hi
Major General
Major General
 
Posts: 1619
Joined: Thu Feb 01, 2007 9:28 pm
Reputation: 0

Unread postAuthor: experament-u2 » Sat Jun 02, 2007 12:52 pm

hi wrote:if that is an accurate picure, then the problem is that there is no air in front of the piston to push it back. try using a tee that is a little bigger.


iv alredy constructed this gun and the 20mm tee is crucial in my overall design

is there anyway i can make some space in front of the piston? maby remove some
  • 0

Attachments
adhq.JPG
adhq.JPG (6.04 KiB) Viewed 343 times
User avatar
experament-u2
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 469
Joined: Tue Dec 26, 2006 11:18 pm
Reputation: 0

Unread postAuthor: hi » Sat Jun 02, 2007 12:59 pm

doubt it. think you just need a slightly larger tee.

you might get away with drilling holes, but that would weaken it, so i dont think its worth it.
  • 0

"physics, gravity, and law enforcement are the only things that prevent me from operating at my full potential" - not sure, but i like the quote

you know you are not an engineer if you have to remind yourself "left loosy righty tighty"
User avatar
hi
Major General
Major General
 
Posts: 1619
Joined: Thu Feb 01, 2007 9:28 pm
Reputation: 0

Next

Return to Pneumatic Cannon Discussion

Who is online

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

Reputation System ©'