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Old 01-12-2005, 09:57 AM #1
Stray Bullet
 
 
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Advanced theory on A80 spool valve?

OK, so this is what I'm guessing at and been wondering about for sometime. If there was a way to get the main spool to close faster and farther on the dump chamber open cycle, it might increase gas efficiency, lower shooting pressure and reduce the report by:

The dump chamber would empty faster:

1. Thus applying a higher pressure and higher volume of gas to the ball.

By sealing the charge chamber faster it would:

1. Reduce the leakage from the charge chamber lowering the volume used in each shot.

2. Reduce the report because only the exact pressure is needed to propel the ball and no extra volume is vented down the barrel.

Now all you techies fill in the gaps. Is this a reality or am I under a misconception that the original claims of Assault 80 efficiency not scientifically possible.
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Old 01-12-2005, 10:56 AM #2
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Interesting ideas, if I was a little smarter I might be able to help :-). I'm still trying to figure out the finer points of it's operation. If I do run across anything you guys will be the first to know!

Avery
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Old 01-12-2005, 11:01 AM #3
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Your smart enough alright. It took me about 2 months to figure it out myself. I got brain cramps on the regulator and my skull went super nova when the main spool operation came to me. Bummer, I was hoping that you would be able to add to the disscussion.
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Old 01-12-2005, 11:14 AM #4
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Quote:
Originally posted by Stray Bullet
It took me about 2 months to figure it out myself. I got brain cramps on the regulator and my skull went super nova when the main spool operation came to me. .
I hear ya, I just figured out how the spool / bolt system works (I was thinking about it all wrong before). I'm still working on getting the main presusure / LPR pressure / dwell all balanced right , since changing the HPR pressure requires a higher LPR pressure to move the spool, and then of course theh effects of the dwell and all the other stuff like how how quickly the dump chamber charges, my brain is starting to hurt already........... I'll think about it when my brain cools down.
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Old 01-12-2005, 11:33 AM #5
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You got it. WMP probably dumped the adjustable velocity board because of that exact reason. If you understand the relationship it's not that big of a deal. With a delrin spool I was able to turn down the LPR by 10-13psi with the same effect.
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Old 01-12-2005, 11:51 AM #6
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Do you have a gauge on your solenoid / LPR / front block somewhere? It seems that it uses a pretty high LPR pressure (I'd guess around 100-125 PSI) but that's just a guess. I suppose I should have found a way to measure it first.....
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Old 01-13-2005, 01:02 AM #7
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The SS noid has a guage port. Don't know if it reads the HP or LP. Never really took notice but it might be the LP because it reads 126. Now if you take the dia of the main spool of .553/2 = .2765 squared = .7645225 x pi = .240181826 x 126 = 30 pounds of force. Now thats if the pressure is up that high instantly in the chamber which I doubt. Considering it has to collapse the main spring in what, 100ms at the very most, and if you stick you finger in the breach it barely pinches that's not bad math.
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Old 01-13-2005, 09:34 AM #8
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One thing I've noticed is (on this one at least) it seems that if you increase the dwell by hitting the velocity button you can lower tyhe LPR and lower the bolt pressure. Seems like the dwell is set so low that it requires a slightly higher LPR pressure to compensate.

One thing I'd given a little thought to is how well the dump chamber seals during the charge portion of the cycle. It looiks like it works pretty much like a two stage mayhem running in open bolt mode (I think Sniper1rfa basically has a closed bolt Assault in a mayhem body). I'm interested in sealing the dump chamber better, and seeing what that does. Then you could have it selectable between open and closed bolt.
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Old 01-13-2005, 11:40 AM #9
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The dump chamber is closed well if the bolt seal, where the tip of the spool joins it, is damage free. Be extremely careful when using your custom metal tip spool. If your tolerances are off just by a little the spool could damade the bolt seal. Thats another reason why the metal tip idea turned me off. Take off you barrel and shoot the Assault. The noise it makes should be a loud high pitched pronounced crack, not a pop, no hiss. Something like a fire cracker. It's almost painfull in a small room.
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Old 01-13-2005, 11:51 AM #10
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What I'm looking for is a way to open the seal between the bolt and spool faster. Increase the flow through the bolt by trying to get the spool to return farther after the LP has been released.
It could be done several ways.
1. Vent the LP faster.
Thats why I was so intrested in the Rainmaker solenoid modification. Because the venting is done right at the back if the LP spool chamber. Rather than at the front block.
2. Effect the action of the spool.
This is trickey but I think I've got several ideas that might be worth something, money wise and maybe not, but time will tell.
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Old 01-13-2005, 12:01 PM #11
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As far as 1 goes it may be accomplished by what I'm doing as I was going to put a spare Clippard QEV right on the spool housing, and have the solenoid connected by about one inch of tube.

Any cool ideas on #2 you feel like sharing?

I still need to get some different (and harder orings) to work on the spool tip. I want to fix the marring of the inside of the bolt and still have a spool that'll last forever. Any new findings with the speed spool?
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Old 01-13-2005, 02:47 PM #12
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You need a 90 duro oring for the spool tip. Unfortunately if the poppet surface, bolt seal, is marred you can't cut more material away to fix it. The angle is critical to a good dump chamber seal. Call WMP and order a new one.
As for the Clippard QEV it will vent at 70psi if your running the LP at 125psi.

OK
1. Just like you did in the previous spool insert a core of alu possibly threaded. Diameter about .125'

Here is a pic
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Old 01-13-2005, 03:30 PM #13
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As soon as I get a large enough piece I'll just make a new bolt, I hate waiting anyway.

I'm about to make a new spool without the "larger surface area" mod. I want to see how that'll affect the necessary LPR pressure, I think with the larger area I'm needingh a higher LPR pressure.

Here's what she looks like right now:

http://home.comcast.net/~amcfall/***...ff/assault.jpg
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Old 01-13-2005, 04:54 PM #14
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Cool. Go to a place that sells oring chord and get some 90/89 duro stuff to put in the back. It might just help reduce the recoil associated with the bolt/spool slamming back into it's resting position.

Cool pic.
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Old 01-17-2005, 09:09 PM #15
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She's ready for some chrono -ing tomorrow:



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Old 01-17-2005, 09:28 PM #16
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Looks good...just get rid of that stock cap and I'll look at it again lol. Do you want it on the website?
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Old 01-18-2005, 09:29 AM #17
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Nice, very nice.
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Old 01-18-2005, 09:37 AM #18
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Thanks. Polish- If I manage to finish it that'd be cool. Right now it's got really bad blowback, and sounds a little funny... I wonder if it's sealing against my new bolt.

Avery
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Old 01-18-2005, 10:43 AM #19
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The angle at which the bolt seat is cut is critical to the seal. Just a few degrees off and it won't work. I know because I've had experance with it. The blowback could be from the LPR being set too low or from not enough flow. I'm telling you the regulators on the Assault are fast, really fast. Or the dump chamber is leaking so bad it's flowing into the neck. I suspect it's the LPR though.
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Old 01-18-2005, 03:02 PM #20
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Lemme show you how to NOT build a bolt. I'll get a pic up on the website in a few.

This was a test done by Kirk and Daniel to see if they could lighten a bolt and pull a stronger charge without messing with pressure :

http://www.geocities.com/polish_guy0/spool.html
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