First Airgun

[Alster370]

Can i house a piston valve inside a compression tee? I was wary because it isnt the same diameter all the way though.

[Gun Freak]

Yes, it's been done before.

[Alster370]

Would it require any specialist tools? (lathe, pillar drill etc)

Also I have found a pump in my garage, its a SPECIALISED WINDPUMP which apparently goes to 220psi. Are pumps fitted with bleed valves? If so Could I possibly remove it so I can take the pump to 400psi? Or allow it to pump to higher pressures some other way?

Its made of steel and other strong materials so I think It could handle the extra pressure.

thanks

[Gun Freak]

As far as I know you can use standard compression fittings. As for the pump, if it looks strong enough to go higher then you can try, but you will have trouble pushing it at high pressure... I don't think it has any sort of bleed valve. However if you exceed the pressure on your gauge too far, the gauge may well become a bleed valve

[Alster370]

How would I do it? Could you provide me with a link? I cant seem to find any referance of a compression fitting used to house a piston anywhere.

Im also stuck between two pumps, The beto 400psi shock pump (£13) or the SCOTT Shock Pump Pro 600 ( 600psi/£35). I would normally go for the higher pressure pump but I dont want the push my compression fittings too far.

[Crna Legija]

this looks like a comp tee. id use something els for the barrel seal part that one is ghetto.

[mark.f]

A piston valve could be made in a compression tee, but you will either have to use very thick-walled tubing for the piston track (to bring the ID of the track equal to or smaller than the ID of the middle of the tee), or use a compression tee one size larger than your piston track.

If you are using copper, solder bushings on the outside of your piston track that bring the OD up to the ID the compression fitting is designed for.

Another way is to drill out the center of the compression fitting to increase clearance.

[Gun Freak]

The 600 psi pump has probably such a low diameter pump head it would take ages to pump up your cannon, but if you want to spend the extra money and time on it, go for it.

[Alster370]

It would have that advantage over the beto pump that it would require less strength to reach 400psi, which would be good since it will be strapped underneath the barrel so usually I will only have one hand to pump it.

Ive also found that when a pump gets near psi limit it becomes less capable to pressurise the chamber any further. Take my floor pump for example, it will do 160psi and usually fill the chamber at about 5 psi per stroke, but when I get past 130psi it becomes more like 1 or 2 psi per stroke.

I wouldnt mind chatting to people who own either of these pumps to get an idea of thier performance. I know lots of people own these beto pumps or some variation of them, but I think Ive only seen one person using the scotts pump. Shame I cant remember who it was.

[Alster370]

Sorry for the double post but could I house a piston valve in a solder ring tee? I if so how would i go about it? I would like to redo the whole gun using solder ring fittings to reduce its bulkyness and to make it more secure but I would use high strength epoxy instead of solder.

One more thing... how do I embed pictures into a post? I would love to post a big update on the gun so far.

[Labtecpower]

upload the pictures on imageshack or similar, and copy the forum code in the message box.

[Alster370]

I finally got GGDT working on my window 7 pc, so I could now see some rough performance scores. I have now realised I made a big mistake, the caliber is too small for the size of the gun. When I dialed down the figures I realised I could make a pistol with piston valve and a 1" cubed volume chamber achive just shy of 500fps with a 6mm steel ball at 400psi.

So I have decided to change the design to a pistol instead. I will prophably head down to PTS and get most of the supplies I need and hopefullly I should be done (mechanics wise) by Monday, then I can give it a good paintjob.

EDIT: I have aquired most of the parts now here is the chamber(not epoxied yet)



Ive just ordered some Permatex Permapoxy which is rated at 4500PSI. Hopefully it should arrive thursday.

[Gun Freak]

Your album has a password... can't see the picture

[jackssmirkingrevenge]

Shiny

[Technician1002]

Naw, that's not shiney. It needs polish.