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 83 users online :: 3 registered, 0 hidden and 80 guests


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

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

The Team
Administrators
Global Moderators
global_moderators.png CS

Coaxial Cannon making weird sound

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

Coaxial Cannon making weird sound

Unread postAuthor: iisthemuffin » Sun Oct 19, 2008 8:06 pm

I just finsished my first full-sized coaxial cannon. It seals perfectly might i add.

Well i just test fired at 60 PSI. And when i fired it shot but it made a weird noise. If you've ever played paintball, it sounded kind of like the sound guns make whent hey run out of co2. You know, that bdddda sound. It wasnt as long as when a paintball gun does it. It was like 2 pops. The projectile shot but it sounded much different than any cannon ive heard and much different than i expected. Does anyone know why?

Im piloting with a 1/2 ball valve and my chamber is 2 inch and the barrel is 1 inch. I guess it has something to do with the piston.

Any ideas?
  • 0

Poop.
User avatar
iisthemuffin
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 497
Joined: Sun May 11, 2008 2:38 pm
Reputation: 0

Unread postAuthor: jrrdw » Sun Oct 19, 2008 8:21 pm

Is the power good?
  • 0

When life gives you lemons...throw them back they suck!
User avatar
jrrdw
Donating Moderator
Donating Moderator
 
Posts: 6540
Joined: Wed Nov 16, 2005 5:11 pm
Location: Maryland
Country: United States (us)
Reputation: 25

Unread postAuthor: Gippeto » Sun Oct 19, 2008 8:29 pm

How much total piston travel do you have?
  • 0

"It could be that the purpose of your life is to serve as a warning to others" – unknown

Liberalism is a mental disorder, reality is it's cure.
User avatar
Gippeto
Donating Member
Donating Member
 
Posts: 2394
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Reputation: 11

Unread postAuthor: MrCrowley » Sun Oct 19, 2008 11:08 pm

How good of a fit is the piston?
  • 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: jimmy101 » Mon Oct 20, 2008 10:05 am

Perhaps the ball valve is opening too slowly causing the valve to honk. Does it seem to be dependent on how fast (and forcefully) you open the ball valve?
  • 0

Image

jimmy101
Lieutenant General
Lieutenant General
 
Posts: 3130
Joined: Wed Mar 28, 2007 9:48 am
Location: Greenwood, Indiana
Country: United States (us)
Reputation: 7

Unread postAuthor: mark.f » Mon Oct 20, 2008 10:35 am

A 1/2" ball valve should be sufficient for a 2" piston. As jimmy said, how fast are you opening the valve. Also, the fit of the piston could affect this as well...
  • 0

User avatar
mark.f
Donating Member
Donating Member
 
Posts: 3465
Joined: Sat May 06, 2006 11:18 am
Country: United States (us)
Reputation: 21

Unread postAuthor: Demon » Mon Oct 20, 2008 11:57 am

I think it might be the sealing surface, if it's not enough tightened, it will
vibrate when air goes in the cannon causing honking.

i already had this problem with a coaxial....
  • 0

User avatar
Demon
Colonel
Colonel
 
Posts: 743
Joined: Sun Apr 13, 2008 8:46 am
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: iisthemuffin » Mon Oct 20, 2008 3:54 pm

The piston is tight but will move when pushed with a little bit of force.

I have more piston travel than i should but i was not sure how to reduce that. I was thinking maybe putting a pill bottle on the back my piston to reduce it is about 1/4 inch.

Im going to go test it for power and distance right now to see if the honking sound will really affect anything.

Well reply back if you dont mind and i will keep you updated.
  • 0

Poop.
User avatar
iisthemuffin
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 497
Joined: Sun May 11, 2008 2:38 pm
Reputation: 0

Unread postAuthor: Gippeto » Mon Oct 20, 2008 4:03 pm

What's the pilot volume like?
  • 0

"It could be that the purpose of your life is to serve as a warning to others" – unknown

Liberalism is a mental disorder, reality is it's cure.
User avatar
Gippeto
Donating Member
Donating Member
 
Posts: 2394
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Reputation: 11

Unread postAuthor: iisthemuffin » Mon Oct 20, 2008 4:27 pm

Uhh maybe a little under two inches.

I just realized i had a sprinkler valve laying in my yard. I threw that on the back instead of the 1/2 inch ball valve. When i try to pilot, it honks real loud out of the sprinkler valve and then the piston pilots and just a little air comes from the barrel.

I assume the reason for this is because of the flow restriction.

On the pilot side i have a 2 inch to a half inch bushing and then a 1/2 inch nipple screwed into it and then a 1/2 inch to one inch adapter and then the 1 inch sprinkler valve.


If i get a 2 inch to 1 inch bushing instead of the 2 inch to 1/2 inch businhg and screw the sprinkler straight in that should fix this problem shouldnt it? Im pretty sure but i just want to confirm it.
  • 0

Poop.
User avatar
iisthemuffin
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 497
Joined: Sun May 11, 2008 2:38 pm
Reputation: 0

Unread postAuthor: Gippeto » Mon Oct 20, 2008 8:09 pm

You need to be very specific if you're going to simply describe things.

Do you mean your piloting route is 2" long? Or do you mean your pilot volume is 2 cubic inches?

Spending more money before finding the problem isn't going to help you.

There is something out of whack with this, and it needs to be found first.

A complete, accurate, and current description seems to be in order here.

Is there any way you can post pictures?
  • 0

"It could be that the purpose of your life is to serve as a warning to others" – unknown

Liberalism is a mental disorder, reality is it's cure.
User avatar
Gippeto
Donating Member
Donating Member
 
Posts: 2394
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Reputation: 11

Unread postAuthor: iisthemuffin » Tue Oct 21, 2008 10:32 am

I dont have my camera right now but i will try to explain better.

With the back of my cannon opened, where the piston goes, i push my piston into the pipe and i push it up against the barrel and then there is a little under two inches of pipe left behind the piston, which is where the piston would travel.

I hope that makes more sense. I know that is way too much but i accidently glued my barrel into the bushing a little short.
  • 0

Poop.
User avatar
iisthemuffin
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 497
Joined: Sun May 11, 2008 2:38 pm
Reputation: 0

Unread postAuthor: Gippeto » Tue Oct 21, 2008 11:08 am

Stuff happens. :)

I think you have piston bounce. ie. The pilot volume is re-compressing, and causing the piston to reverse direction.

That's why it honks.

Take up the volume with something. The spacer should be something which will not compress under pressure. (Don't use foam.)

Leave 1/4" to 3/8" total piston travel.

Wood will likely be your best bet.

Also, I checked the other thread about your piston, and could not find out how you made your piston. If it's hollow at the back, it is likely contributing to the problem as well.
  • 0

"It could be that the purpose of your life is to serve as a warning to others" – unknown

Liberalism is a mental disorder, reality is it's cure.
User avatar
Gippeto
Donating Member
Donating Member
 
Posts: 2394
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Reputation: 11

Unread postAuthor: iisthemuffin » Tue Oct 21, 2008 11:32 am

Thank you for your help.

How should the wood fit? Should it be as tight as the piston is? or just connected to the back of the piston to take up space without really acting as part of the piston.

And i believe the thread you are speaking of is about my mini coaxial. That piston was made entirely of epoxy.

This piston is made drom an end cap. And yes the back side is hollow. Should i feel it in to help fix the problem?
  • 0

Poop.
User avatar
iisthemuffin
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 497
Joined: Sun May 11, 2008 2:38 pm
Reputation: 0

Unread postAuthor: Gippeto » Tue Oct 21, 2008 1:30 pm

iisthemuffin wrote:Thank you for your help.

How should the wood fit? Should it be as tight as the piston is? or just connected to the back of the piston to take up space without really acting as part of the piston.


If you connect the wood to the piston, it becomes part of the piston, doesn't it? Don't connect it. It should fit reasonably close, if it fits as good as the piston, that's good enough.



And i believe the thread you are speaking of is about my mini coaxial. That piston was made entirely of epoxy.


No, you have a thread looking for a 2" piston.



This piston is made drom an end cap. And yes the back side is hollow. Should i feel it in to help fix the problem?



Yes, seal off the back side, or fill it in with something. (not foam) This extra volume is adding to your pilot volume, compounding the problem.




Do you have another end cap? If you were to put two end caps, on a piece of pipe (just the right length?), the finished product should take care of both problems. :D ( Jeeze, I think I read that somewhere! :wink: )

Don't forget some sort of bumper.(you can use foam for this) I suggest that bumpers be attached to the bushing that the piston impacts. This way, they do not increase the weight of the piston.


Edit: Note to self: Do not insert comments when quoting! :banghead:
  • 0

"It could be that the purpose of your life is to serve as a warning to others" – unknown

Liberalism is a mental disorder, reality is it's cure.
User avatar
Gippeto
Donating Member
Donating Member
 
Posts: 2394
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Reputation: 11

Next

Return to Pneumatic Cannon Discussion

Who is online

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

Reputation System ©'