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auto piston v2.0

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auto piston v2.0

Unread postAuthor: jackssmirkingrevenge » Fri Dec 21, 2007 5:07 am

Following the abject failure of my auto-piston prototype and the suggestions made on the thread (cheers clide :D) I've come up with a less sophisticated design as per the attached diagram.

The firing cycle is as follows:

1) the firing chamber and piston unit start to fill with compressed air

2) when the force on the piston is greater than the force provided by the spring, the piston moves down slightly

3) this movement exposes the wider section of the piston to the force of the compressed air, pushing it down allowing the chamber to vent

4) as the pressure decreases, the spring pushes the piston back up and the cycle can continue.

The theory is sound but fleshing it out in practice looks a bit tricky as is, I'm still trying to refine the idea but just thinking aloud for now.

edit: A quick sketch of a possible refinement with the piston in two parts. The breech vent is sealed by a floating component, when the chamber is pressurised the piston component is forced down, eventually pulling the floating part down with it. The chamber is vented, allowing the piston to be returned by the spring and resealed. The advantage of this system would be that the main spring doesn't have to be strong enough to overcome the pressure, just enough to overcome the friction of the piston.

edit 2: here's the above idea as an animation

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Last edited by jackssmirkingrevenge on Sun Dec 23, 2007 4:24 am, edited 1 time in total.
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Unread postAuthor: Carlman » Fri Dec 21, 2007 7:53 am

looks nice as always, how in the world do you come up with all these ideas? Cant wait to see it in action.
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Unread postAuthor: ALIHISGREAT » Fri Dec 21, 2007 8:07 am

getting the right strength of spring could be tricky, i'm guessing you want it to hold about 100psi then start venting? other than that its a sound design which will hopefully work so i can copy it :wink:
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Unread postAuthor: clide » Fri Dec 21, 2007 2:51 pm

I think the floating valve is probably a little overkill. If you keep the outlet pretty close in diameter to the piston, then there won't be much force that the spring needs to hold back. Well, until it opens, but a bumper can be used to take that force rather than the spring.
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Unread postAuthor: jackssmirkingrevenge » Fri Dec 21, 2007 3:10 pm

clide wrote:I think the floating valve is probably a little overkill.


In that case, I'll DEFINITELY make it :D wheee!

lol sorry but I'm still absolutely arse'oled and I still have two more parties to attend, yippee, joy to the world and all that :)
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Unread postAuthor: rna_duelers » Fri Dec 21, 2007 5:32 pm

This is a moment :cry: to remember :cry: . JSR, PUI Beautiful, and there is nothing wrong with the overkill means more high flowing pressurized air!
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Unread postAuthor: Fnord » Fri Dec 21, 2007 7:35 pm

I'm betting Jack's gonna wake up in a ditch tomorrow covered in epoxy or something.
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Unread postAuthor: jrrdw » Fri Dec 21, 2007 7:40 pm

_Fnord wrote:I'm betting Jack's gonna wake up in a ditch tomorrow covered in epoxy or something.


Yea, with......ummm.......spudgun in hand! :shock:
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Unread postAuthor: rna_duelers » Fri Dec 21, 2007 8:06 pm

He'll probably wake up having re invented the wheel cast out of epoxy or something similar.Or just wake up with a thumping head ache and a not so good feeling inside.
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Unread postAuthor: jackssmirkingrevenge » Fri Dec 21, 2007 11:40 pm

rna_duelers wrote:This is a moment :cry: to remember :cry: . JSR, PUI Beautiful


I knew I'd regret this later, but what the hell, it's xmas, ho ho ho and whatnot :)
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Unread postAuthor: Eddbot » Sat Dec 22, 2007 12:14 am

jackssmirkingrevenge wrote:(one would think I rub myself with the stuff in the bedroom :roll: :D <sup>*</sup> )


i'm never gonna forget that :D
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Unread postAuthor: jackssmirkingrevenge » Sat Dec 22, 2007 4:13 am

Eddbot wrote:i'm never gonna forget that :D


Oh dear *sigh*

anyway, back on topic, I think the floating piston idea thing wouldn't be too hard to make, I've already made something similar for a completely different project.
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Unread postAuthor: Carlman » Sat Dec 22, 2007 4:17 am

hmm so u quoted yourself saying some that eddbot said...
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Unread postAuthor: jackssmirkingrevenge » Sat Dec 22, 2007 4:19 am

there, fixed :p
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Unread postAuthor: Carlman » Sat Dec 22, 2007 4:20 am

just letting you know and the piston looks professional grade although i have no idea how it works...yet
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