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Posted: Fri Nov 09, 2007 3:18 am
by Novacastrian
I think one could get the piston to travel the distance. However it would be a major pain.

Posted: Fri Nov 09, 2007 3:20 am
by jackssmirkingrevenge
Novacastrian wrote:I think one could get the piston to travel the distance.
If the piston blocks off the air feed as soon as it starts moving (need not be a 100% seal) it should be plausible. I think I found my next project :)

Posted: Fri Nov 09, 2007 3:30 am
by Novacastrian
Not before me you have'nt :twisted: :geek:

Posted: Fri Nov 09, 2007 3:36 am
by jackssmirkingrevenge
oooh, a bit oh healthy competition, just what I need to get off my arse and back to the workshop. Of course it's colder now, and epoxy takes forever to cure, so it might be a bit of a long-term thing...

Posted: Fri Nov 09, 2007 3:38 am
by Novacastrian
Nothing under a 3 month period myself :wink:

Posted: Fri Nov 09, 2007 3:42 am
by Hubb
Can I make it too? :D

Edit: Just to note. Thinking the piston would stop once the pilot is sealed (or stopped by the spring, bumper, etc) this could be designed, by placing the pilot in the correct location, to suit that "D/4" rule...you know, to please the Efficiency Gods.

Posted: Fri Nov 09, 2007 3:47 am
by Novacastrian
hubb017 wrote:Can I make it too? :D
Why of coarse my dear friend, what you will need is a bottle opener, a full bottle (preferably alcholic), and some spare time :P Recreational narcotics may also be used of coarse :D
Oh that and some good luck and you are on your way hubb old chap :wink:

Edit: Yes it will honk like a mo-fo unless (insert smart idea here).

Posted: Fri Nov 09, 2007 3:50 am
by Hubb
Well, to tell the truth, this designed is something I thought about while "on the throne." The project I am currently working on is a pump action revolver type deal, not really needing this sort of valve.

Maybe this will be my next project...that is if I still have my bottle opener.

Posted: Fri Nov 09, 2007 4:12 am
by jackssmirkingrevenge
I think we can waive the D/4 rule in this case to make sure the piston travels back far enough to allow a new projectile to drop in the breech.
Well, to tell the truth, this designed is something I thought about while "on the throne."

TMI TMI TMI TMI!

:shock:

Were you squeezing them out full-auto lolol

:D

Posted: Fri Nov 09, 2007 4:17 am
by Novacastrian
jackssmirkingrevenge wrote:I think we can waive the D/4 rule in this case to make sure the piston travels back far enough to allow a new projectile to drop in the breech.
Well, to tell the truth, this designed is something I thought about while "on the throne."

TMI TMI TMI TMI!

:shock:

Were you squeezing them out full-auto lolol

:D
Again you haved killed me JSR :D

Posted: Fri Nov 09, 2007 4:23 am
by Hubb
Now that I think about it, I guess this is a s@#$y idea :D

Posted: Fri Nov 09, 2007 4:29 am
by jackssmirkingrevenge
Ok, I think we're taken the scatological theme far enough, back to projectile firing that does not involve chocolate starfish :)

Posted: Fri Nov 09, 2007 4:38 am
by Hubb
JSR; looking at your last diagram, do you think it would be necessary to add the spring? Would not filling the chamber be sufficient enough to seal the pilot?

Also, Mark uses a 90psi pop off. Do you think the piston would prematurely open if the the pilot area filled too fast?

Posted: Fri Nov 09, 2007 4:46 am
by jackssmirkingrevenge
JSR; looking at your last diagram, do you think it would be necessary to add the spring? Would not filling the chamber be sufficient enough to seal the pilot?
The spring would increase the pressure difference required to open the piston, which in this case is a good thing as it would give the chamber more time to fill.
Also, Mark uses a 90psi pop off. Do you think the piston would prematurely open if the the pilot area filled too fast?
Going off prematurely is indeed a concern in this case (oh dear, let's not go donw another route of innuendo :roll: ) - perhaps the best idea is to have a reasonable strong spring and fill from the chamber side, though you'd need a way to regulate the air inlet - fill the chamber too quickly and the pressure won't build up in the pilot chamber and the piston will never seal.

Posted: Fri Nov 09, 2007 4:54 am
by Hubb
Concerning the whole premature piloting, by putting a check valve on the piston, the equalization hole could be much larger to reduce this risk. This, in turn, would also allow for a faster fill, which will lead to a faster rate of fire.