megalomania
May 24th, 2003, 02:41 PM
Colza
New Member
Posts: 12
From: New Zealand
Registered: FEB 2001
posted 02-20-2001 05:29 AM
--------------------------------------------------------------------------------
I have tried building an air pressure spud canon but I can't get a good seal between the ball valve and the pressure chamber and the pressure chamber and the bicycle tyre valve? has anyone ever made one of these succesfully? anyone got any ideas?
Anthony
Moderator
Posts: 2306
From: England
Registered: SEP 2000
posted 02-20-2001 09:56 AM
--------------------------------------------------------------------------------
I have made several pneumatic spudguns, in order for us to help you, you need to tell us what is exactly is wrong, what materials you have used, how you you've joined them etc.
Colza
New Member
Posts: 12
From: New Zealand
Registered: FEB 2001
posted 02-22-2001 12:40 AM
--------------------------------------------------------------------------------
sorry
shouldv'e thought of that
its a small one (4cm diameter barrel) because i wanted to get it to work before i scaled it up. its made of pvc pipe with a plastic ball valve and a 6 cm pressure chamber and a bicycle tyre valve on the back.
is that more useful?
Colza
BoB-
Frequent Poster
Posts: 679
From:
Registered: SEP 2000
posted 02-22-2001 01:11 AM
--------------------------------------------------------------------------------
By plastic...do you mean PVC? Socket or thread?
Anthony
Moderator
Posts: 2306
From: England
Registered: SEP 2000
posted 02-22-2001 10:46 AM
--------------------------------------------------------------------------------
If the valve is threaded then put some mastik/caulk/PTFE tape on the threads. If it's solvent welded, then you're in a spot of bother.
Is the schrader valve fitted through an end cap? Hopefully its a threaded cap not a solvent welded one.
If its threaded, remove it, take out the bicycle valve out of the hole you drilledi n the cap for it, smear a load of mastik/caulk on the circle of rubber and the base of the valve (the part where it's molded to the inner tube). The pressure inside the air chamber of the cannon will force the rubber circle against the inside oft he end cap giving an air-tight seal.
Colza
New Member
Posts: 12
From: New Zealand
Registered: FEB 2001
posted 03-14-2001 12:16 AM
--------------------------------------------------------------------------------
Thanks for the tip with the bicycle tyre valve that seems to have worked. I have got hold of a small solenoid valve (im guessing they work better than ball valves?) but it is only 3 8ths of an inch i think this is probably too small but will it work?
Maddoc
Moderator
Posts: 537
From: Dizneland
Registered: SEP 2000
posted 03-14-2001 03:05 PM
--------------------------------------------------------------------------------
I use a Motercycle tire valve, you can buy them at all motersbike stores.
they are like an ordinary tire valve, but have a securing nut and seal, no glue, no sealant, good seal, no fuss.
------------------
Whoa, where my fingers?
-Colza-
New Member
Posts: 19
From: New Zealand
Registered: APR 2001
posted 04-01-2001 06:41 AM
--------------------------------------------------------------------------------
I scrapped that piece of shit mess! (the above spudgun)
The new one WORKS.
but....
on the end of the pressure chamber is a screw thread PVC end cap. the valve I got is a special one where the pressure inside the chamber forces a little rubber cup tighter onto the end cap keeping the seal good. the problem is that connecting the pump to it tends to push the vale back the other way and it dissapears into the gun and you have to unscrew it all and fish it back out! I have tried using thread tape(lots of) to help it fit tighter. didn't work. Silicon sealant wouldn't stick to the rubber. any ideas on keeping the bastard there?
------------------
Fear no more the lightning-flash,
Nor the all-dreaded thunder stone;
Fear not slander, censure rash;
Thou hast finish'd joy and moan;
All lovers young, all lovers must
Consign to thee, and come to dust.
Anthony
Moderator
Posts: 2306
From: England
Registered: SEP 2000
posted 04-01-2001 07:33 PM
--------------------------------------------------------------------------------
There aren't many glues that will stick well to rubber, so try using or making a large washer and gluing to to the PVC cap so that the whole valve sits inside the hole in teh washer. So what you've got is a ring around the valve that is level with the end of the valve. Then glue a washer with a smaller hole on top that the valve will get pushed against:
_______________
|..||.|***|.||.|
***** ****
________________
|.....cap.......|
|***| <- valve
||.......|| <-first washer (minus dots)
***** **** <- second washer
Bow to my almighty artwork.
New Member
Posts: 12
From: New Zealand
Registered: FEB 2001
posted 02-20-2001 05:29 AM
--------------------------------------------------------------------------------
I have tried building an air pressure spud canon but I can't get a good seal between the ball valve and the pressure chamber and the pressure chamber and the bicycle tyre valve? has anyone ever made one of these succesfully? anyone got any ideas?
Anthony
Moderator
Posts: 2306
From: England
Registered: SEP 2000
posted 02-20-2001 09:56 AM
--------------------------------------------------------------------------------
I have made several pneumatic spudguns, in order for us to help you, you need to tell us what is exactly is wrong, what materials you have used, how you you've joined them etc.
Colza
New Member
Posts: 12
From: New Zealand
Registered: FEB 2001
posted 02-22-2001 12:40 AM
--------------------------------------------------------------------------------
sorry
shouldv'e thought of that
its a small one (4cm diameter barrel) because i wanted to get it to work before i scaled it up. its made of pvc pipe with a plastic ball valve and a 6 cm pressure chamber and a bicycle tyre valve on the back.
is that more useful?
Colza
BoB-
Frequent Poster
Posts: 679
From:
Registered: SEP 2000
posted 02-22-2001 01:11 AM
--------------------------------------------------------------------------------
By plastic...do you mean PVC? Socket or thread?
Anthony
Moderator
Posts: 2306
From: England
Registered: SEP 2000
posted 02-22-2001 10:46 AM
--------------------------------------------------------------------------------
If the valve is threaded then put some mastik/caulk/PTFE tape on the threads. If it's solvent welded, then you're in a spot of bother.
Is the schrader valve fitted through an end cap? Hopefully its a threaded cap not a solvent welded one.
If its threaded, remove it, take out the bicycle valve out of the hole you drilledi n the cap for it, smear a load of mastik/caulk on the circle of rubber and the base of the valve (the part where it's molded to the inner tube). The pressure inside the air chamber of the cannon will force the rubber circle against the inside oft he end cap giving an air-tight seal.
Colza
New Member
Posts: 12
From: New Zealand
Registered: FEB 2001
posted 03-14-2001 12:16 AM
--------------------------------------------------------------------------------
Thanks for the tip with the bicycle tyre valve that seems to have worked. I have got hold of a small solenoid valve (im guessing they work better than ball valves?) but it is only 3 8ths of an inch i think this is probably too small but will it work?
Maddoc
Moderator
Posts: 537
From: Dizneland
Registered: SEP 2000
posted 03-14-2001 03:05 PM
--------------------------------------------------------------------------------
I use a Motercycle tire valve, you can buy them at all motersbike stores.
they are like an ordinary tire valve, but have a securing nut and seal, no glue, no sealant, good seal, no fuss.
------------------
Whoa, where my fingers?
-Colza-
New Member
Posts: 19
From: New Zealand
Registered: APR 2001
posted 04-01-2001 06:41 AM
--------------------------------------------------------------------------------
I scrapped that piece of shit mess! (the above spudgun)
The new one WORKS.
but....
on the end of the pressure chamber is a screw thread PVC end cap. the valve I got is a special one where the pressure inside the chamber forces a little rubber cup tighter onto the end cap keeping the seal good. the problem is that connecting the pump to it tends to push the vale back the other way and it dissapears into the gun and you have to unscrew it all and fish it back out! I have tried using thread tape(lots of) to help it fit tighter. didn't work. Silicon sealant wouldn't stick to the rubber. any ideas on keeping the bastard there?
------------------
Fear no more the lightning-flash,
Nor the all-dreaded thunder stone;
Fear not slander, censure rash;
Thou hast finish'd joy and moan;
All lovers young, all lovers must
Consign to thee, and come to dust.
Anthony
Moderator
Posts: 2306
From: England
Registered: SEP 2000
posted 04-01-2001 07:33 PM
--------------------------------------------------------------------------------
There aren't many glues that will stick well to rubber, so try using or making a large washer and gluing to to the PVC cap so that the whole valve sits inside the hole in teh washer. So what you've got is a ring around the valve that is level with the end of the valve. Then glue a washer with a smaller hole on top that the valve will get pushed against:
_______________
|..||.|***|.||.|
***** ****
________________
|.....cap.......|
|***| <- valve
||.......|| <-first washer (minus dots)
***** **** <- second washer
Bow to my almighty artwork.