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Posted: Wed Dec 19, 2007 9:43 pm
by Killjoy
Yeah I think a thick piece of rubber should be able to handle the impact force of the piston. And thats fortunate you were able to find parts for repair without much trouble.

Posted: Thu Dec 20, 2007 1:47 am
by rna_duelers
Try getting some bumper stop rubber out of a coil over suspension component,they are designed to absorb a lot of shot from bottoming out.The valve spring is also and idea.

Posted: Thu Dec 20, 2007 3:23 pm
by Brian the brain
I'm not sure on how a piston hybrid works..I haven't followed the advancements in that field.Anything having to do with combustion ( hybrid or otherwise) is considered a firearm and illegal in my country.
Since I have no complaints about the power of my pneumatics, I haven't looked into hybrids.

I do however have a theory on how one could be made.The picture ( although very schematic and incomplete) should explain.
Fuel meters etc have been left out.

It basicly functions like a piston pneumatic, it is just set off by the ignition.
Add an exaust valve and it can act like both.
As the piston is forced back the pop-off valve( or maybe several, to be safe) exhausts the pilot.
If only I could figure out fueling and stuff, I COULD easily turn my cannons into hybrids.

One thing I do know..pistons should ALWAYS be as light as possible, so that should help your problem

( pneumatics stil have their pro's.It's easier to achieve full auto and they don't give off muzzle flash.Neither will they burn up the insides of a silencer..muhahaha)

Posted: Thu Dec 20, 2007 4:32 pm
by Fnord
Your theory is right, that's how they work.

This is a diagram of what mine looks like after the repairs today. There's not much to it, really. Not even a pop-off valve. (a pop-off releases the air behind the valve, causing the piston to slam into the bumper even harder without a cushion of air to slow it down. So in my case not having a pop-off is a good thing)

I drilled holes in the piston to reduce weight and added a rubber stopper as a bumper. I wanted to incorporate a spring into the bumper too, but there wasn't enough room (reduced the piston travel to ~1/2").

Posted: Thu Dec 20, 2007 5:20 pm
by Brian the brain
wow..

I'm pretty sure I thought of that first some years ago.I don't feel like looking it up, but I'm pretty sure.
I never built it however and I'm happy the idea works so well!!
I disgarded the idea and never gave it a second thought...
That's funny...since I don;t even really like hybrids haha..


I don't mean to brag.. and anyone can use this idea, you probably understand it better than I do anyway..It was just one of those things that popped in my head as people were discussing the subject..

Well...anyway..you are actually saying performance could be improved by the safety valve!! ( you didn't mean to but you did!!)
Please try the "floating diaphram"method...i't so much lighter and it makes the pop-off method possible I think.
You could just use a slab of say 3/8 thick neoprene..without reenforcement.It would probably stand up to the pressure needed for a 6x mix..
Just the neoprene disk would mean no more bumper problem..

Posted: Thu Dec 20, 2007 10:15 pm
by clide
Brian the brain wrote:wow..

I'm pretty sure I thought of that first some years ago.I don't feel like looking it up, but I'm pretty sure.
I never built it however and I'm happy the idea works so well!!
I disgarded the idea and never gave it a second thought...
That's funny...since I don;t even really like hybrids haha..
That's actually how the first* hybrid cannon built by DR worked, except he used a sprinkler valve rather than a homemade diaphragm.

*Could be the second hybrid depending on how you define hybrid.