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| clide |
 Posted: 05/07/2007 14:47 PM Post subject: |
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Donating Member
Joined: 06 Mar 2005
Posts: 716
2065.66 Spud Bux
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Nice work, looks like something Spudinator would build (which is a good thing if you don't know who that is)
Now for the questions.
So is the piston just held down by spring pressure? Do you have a hole in the cap so air can escape as the piston moves back? Any reason you chose the chamber sealing configuration for the piston? Barrel sealing would allow you to use a weaker spring and IMO work better in the configuration you were going for.
I just wish you had a video 
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| _Fnord |
| Posted: 05/07/2007 15:08 PM Post subject: |
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reenigne
Joined: 13 Feb 2007
Posts: 1212
1739.50 Spud Bux
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Here are the drawings.. sorry for the low quality, my scanner is broken so I had to use my camera and clean it up the best I could.
Somehow I dont think the piston is quite what everyone expected.
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| Here is the concept drawing. The wiring is a little messy because I knew roughly what I was doing and didnt feel like drawing it out properly. |
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A side view and an exploded view of the piston itself. This isnt the one that broke, its the one that I am getting ready to install.
This isnt exactly scaled right compared to the real thing, btw. |
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| clide |
| Posted: 05/07/2007 15:30 PM Post subject: |
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Donating Member
Joined: 06 Mar 2005
Posts: 716
2065.66 Spud Bux
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Ah, I see, not what was expected at all.
A piston built more like a traditional piston valve would open a a certain pressure and stay open well below the pressure that it opened at (how much below depends on the dimensions)
This one will open a a certain chamber pressure and only stay open enough to maintain that pressure and close again at about that same pressure. Not much of a problem if you are opening at low pressures, but if it is set to open a higher pressures the valve will be choking flow and closing early.
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| _Fnord |
| Posted: 05/07/2007 15:42 PM Post subject: |
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reenigne
Joined: 13 Feb 2007
Posts: 1212
1739.50 Spud Bux
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| With such high pressures involved, at 4x the piston will practically become a projectile. kinetic energy will likely keep it open long enough for most of the gas to vent. I considered this a lot before I made it, and the dryfire yesterday convinced me that it will work.
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| clide |
| Posted: 05/07/2007 15:50 PM Post subject: |
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Donating Member
Joined: 06 Mar 2005
Posts: 716
2065.66 Spud Bux
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Yes, I have no doubt that it will work great when the opening pressure is set well below the peak pressure, but you may run into performance issues if you ever decide to set the opening pressure near the peak pressure.
PS: nice sig 
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| _Fnord |
| Posted: 05/07/2007 15:57 PM Post subject: |
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reenigne
Joined: 13 Feb 2007
Posts: 1212
1739.50 Spud Bux
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Eh.. I'll figure it out
Like I said, this gun is experimental, so if it doesnt work at higher pressures I'll just bang on it until it does.
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| SpudMonster |
| Posted: 05/07/2007 18:43 PM Post subject: |
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1st Lieutenant
Joined: 08 Aug 2005
Posts: 253
195.26 Spud Bux
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| I looked down the barrel of that cannon. I saw a frog. Then I saw Satan.
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| bboymatty |
| Posted: 05/07/2007 22:16 PM Post subject: |
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Staff Sergeant
Joined: 19 Feb 2006
Posts: 110
219.10 Spud Bux
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that looks sooo ghetto, totally post apocalyptic style sh!t going on right there hahaha nice gun
bet its heavy!
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| chaos |
| Posted: 05/08/2007 10:28 AM Post subject: |
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Brigadier General
Joined: 17 Jan 2007
Posts: 1222
913.08 Spud Bux
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man that is "bangin".
but how are you getting a spark in the metal chamber i cant quite see from the pics.
great job you have inspired me to build a hybrid....stainless of course.
peace
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| _Fnord |
| Posted: 05/08/2007 15:06 PM Post subject: |
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reenigne
Joined: 13 Feb 2007
Posts: 1212
1739.50 Spud Bux
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Chaos: I drilled two holes through the reducer then epoxied+super glued the wires into place.
Update: I thought something was fishy here. I shut my regulator all the way off and there was still gas getting through, so I took the thing apart. I discovered one of the o-rings had a large chunk missing from it. Whether it came that way or I somehow damaged it I dont know. I dont think harbor freight will take it back so I just hooked a flow restrictor up in its place. Everything worked out good with that and it let me compact the gun even more.
My dad is going to turn out a brass piston at work so hopefully Ill get to do some real testing soon. The heavier metal should also increase the piston's acceleration time and help correct preformance issues that clide pointed out could happen with higher mixes.
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| cash68 |
| Posted: 05/08/2007 17:57 PM Post subject: |
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2nd Lieutenant
Joined: 29 Apr 2007
Posts: 201
190.31 Spud Bux
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| Add some rusty nails/spikes and it would look perfect. Maybe a few stickers too.
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| jssizzle |
| Posted: 05/08/2007 18:06 PM Post subject: |
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Corporal
Joined: 03 Apr 2007
Posts: 72
186.41 Spud Bux
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Very cool. I'm probably wrong, but the pistol grip on a hybrid seems pretty original to me. Don't paint it. I think a bipod would be cool (on a hybrid? I must be crazy . . .)
I see the FSM!!!!!
www.venganza.org
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| _Fnord |
| Posted: 05/08/2007 18:28 PM Post subject: |
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reenigne
Joined: 13 Feb 2007
Posts: 1212
1739.50 Spud Bux
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heh.. glad to see there are a few of the enlightend on spudfiles.
The name "fnord" and "the spaghetti monster that lurks within the handle" are in fact refences to such in-jokes. my sig kinda is too
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| jssizzle |
| Posted: 05/08/2007 19:04 PM Post subject: |
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Corporal
Joined: 03 Apr 2007
Posts: 72
186.41 Spud Bux
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Hmmm . . . Fnord . . . everytime I read it I think of the fjords or norway. But I doubt thats it. As for your sig . . . I think its some dvd hacking code or something isn't it?
Back on topic!
Name it some small furry rodent.
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| FeLeX |
| Posted: 05/09/2007 9:05 AM Post subject: |
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Captain
Joined: 10 Mar 2007
Posts: 308
254.45 Spud Bux
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Man that thing looks AWESOME. Very original use of a piston. By any chance did you det the system from the propane powered paintball gun (cant remeber what it was called)? I love the fact that it is hand held unlike most of the other hybrids out there.
If there is going to be some kind of voting done then my vote is deffinatly going to you!
Good luck, FeLeX
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