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Unread postPosted: Thu Mar 10, 2011 11:46 am
Author: JDP12
Thanks for the tip on using teflon tape to size up a washer- I dunno why I never thought of that before. Do you glue it in place at all or no?

Unread postPosted: Thu Mar 10, 2011 5:02 pm
Author: jhalek90
i made a piston for my 3/4'' copper T piston valve, and ill share a little secrete with you...

The BEST piston EVER for a valve like this is a solid rubber cork.
well.... its not THE BEST EVER but its supper simple and works...

The one i found at my local hardware store, as designed to fit into 3/4'' copper, and has a VERY slight taper.

Works well.....mine has lasted a few hundred shots at 400-800psi and has never leaked. i pilot it with a non-modded blowgun.

something like this:
Image

Unread postPosted: Thu Mar 10, 2011 6:55 pm
Author: Gun Freak
My piston is for my 2" piston valve. It is extremely heavy though :lol:

I guess it makes sense, how you have all that stuff on it. But I seal the front washers, where it leaks through to the seat, with JB Weld. It is less bulky. Thats what I though you used the rubber for though.

Unread postPosted: Thu Mar 10, 2011 7:08 pm
Author: mark.f
JDP12 wrote:Thanks for the tip on using teflon tape to size up a washer- I dunno why I never thought of that before. Do you glue it in place at all or no?


Nope. It's not great for large size differences but it works on sloppy o-ring grooves just fine. I just wrap it tightly and it stays.

@jhalek: Does it completely seal off the pipe or no? If so how do you accomplish equalization?

@Gun Freak: I see, it's a just a different piston from the one in the thread. I would have used epoxy to seal the leak but I like being able to take apart the piston when I need to.

Unread postPosted: Thu Mar 10, 2011 7:11 pm
Author: Gun Freak
Yeah I didn't post that picture in the original post, but it is somewhere in the thread. I know what you mean by making it undoable. I do the same thing sometimes.

Unread postPosted: Fri Mar 11, 2011 12:23 am
Author: jhalek90
yes, it seals at 100%

It EQs because it has a SLIGHT taper.


Air is able to pass from the pilot, to the chamber, around the piston at the narrow end. the tapper is not as severe as the one in the photo.

Another plus, the corks are very light, and also quite cheap. I got mine for 33 cents.

Unread postPosted: Fri Mar 11, 2011 1:11 am
Author: jackssmirkingrevenge
Plenty of choice here

Unread postPosted: Fri Mar 11, 2011 4:28 am
Author: MRR
I have found a great way to integrate a floating o-ring without the use of that many parts and a minimum of work involved.

Rope Pulley....
Image

They come in different sizes and materials but are very durable. The ones for wire cables are made of hardened steel and withstand even the hardest impacts.

All you have to do is to file a notch into one side to let the air pass through.

ps.: Congrats on your launcher. Looks really badass.

Unread postPosted: Fri Mar 11, 2011 10:28 am
Author: mark.f
Hmm... lots of suggestions. If I ever need to replace the piston I'll look into this stuff. Thanks.

Unread postPosted: Fri Mar 11, 2011 11:05 am
Author: JDP12
as far as rubber corks, I can find them easily at my local hardware stores.

Good idea on the rope pulley

Unread postPosted: Fri Mar 11, 2011 12:39 pm
Author: mark.f
[intercourse] I feel like an idiot now.

Despite the revised pump head, the o-rings are extruding themselves through the clearance gap at pressures above ~220 PSI.

My piston is 3/4" diameter, and type L copper tubing (3/4") is .785" inside diameter.

However,

Working on the pump, I noticed I had somehow bought a piece of type M copper tubing for the pump body, giving a clearance gap of 0.0305".

So, unfortunately, the testing I planned for today is delayed even more until I buy a length of type L and a female adapter to fix this.

Or, I might wait to but a HPA source, since, after cutting down the chamber, I can now get about 14 shots from a fill. Not spectacular, but it's better than 6...

EDIT:

*blares Celebration Day from Zep. III*

Finally got my pump working. As stated, I simply replace the pump body with some 3/4" type L and have no more problems with o-ring extrusion.

However, my piston leaks past ~250 PSI, I've found out. :roll: I'll just have to attack that tomorrow with some dowel rod and stick-on sandpaper I guess. Even with the leak, I just leaned into the pump as hard as a could, but ran out of steam at around 275 PSI (the thing would have been to 450 by then without the leak).

Overall, the HP side of this project is coming along nicely.

Unread postPosted: Sat Mar 12, 2011 5:22 pm
Author: mark.f
Double post, but I want people to see the updated version and video. Tell me what you think!

Unread postPosted: Sat Mar 12, 2011 7:26 pm
Author: POLAND_SPUD
I think you should get larger diam. washers. That should solve the problem

ohh btw am I the only person who has noticed that D_Hall looks almost exactly like Peter from the Family guy ? :)

Unread postPosted: Sat Mar 12, 2011 7:36 pm
Author: Gun Freak
I agree on the washers. I can see why you used those though, if you couldn't get the right sized ones.

Unread postPosted: Sat Mar 12, 2011 8:53 pm
Author: mark.f
First post, people. Updated pictures and damage video. Problems all solved.

(Except my wimpy stature not capable of pumping the gun to 400 PSI.) :lol: