KalNet Message Board

yoda already drew it more than a year ago

http://img685.imageshack.us/img685/4356/hatsmodel2.jpg

you only need restriction and a high force. Yes, it would be nice to have a balanced valve, but I think given the other constraints of the problem its kind of silly to take out a ton of force then add it back in.

With the balanced design that pilots out to a face (you know, the one I've been selling for a year) you get over unity in terms of the force balance (closing force can > opening force) but there is NO evidence to suggest that's needed for a maximally efficient gun.

You only need the valve closure to be SUFFICIENTLY FAST such that you can optimize the rest of the system. Its clear you can get that without adding all this cruft to the system. If you're talking about semis where the kick and ROF matter a lot more, then by all means figuring out a balanced valve setup is nice

but for making this system more efficient? not needed and counterproductive

Does it use the hat you posted about earlier in this thread (close tolerances to hold pressure over the valve?). I assume the magic nipple is some sort of pseudo-regulating pin valve, but you might just be talking about the dynamics of a poppet valve, which exhibit pressure compensating behavior. Without knowing what specific geometries we're talking about it's kind of worthless to wave around numbers for efficiency.

I don't really care about the efficiency claim per se, but I am curious if you've made specific developments to the Nelson valvetrain that make you so confident.



Also, I have a very simple drop in modification I can produce on my 3d printer for phantoms that should boost shot counts very cheaply, assuming my theory is sound.
__________________

I don't think you can expect much more than 75, maybe 80% of adiabatic efficiency, based on what a properly designed valve shows for hpa.

I will say that a very respectable goal would be the ke equivalent of 50 270fps shots. I doubt Nelson valves crest 35 now at that velocity. Too much long tail 200fps bull**** about 45 shots

How much clearance poppet to hat ID

Cupseal tail OD = .247", hat ID = .250".

Our designs were also primarily round 1. Lurker came in and presented a viable way to correct the poor balance in a Nelson system without requiring a new valve body. A problem that both mine and newmaticarsenal's valves exacerbated with the improved flow. Round 2 will be combining the systems to both improve flow and correct the poor dynamics response.

Ryan, by a valve hat, are you referring to a means of closing the valve efficiently with force of air alone?
Yes - although a very light spring should be employed to close the valve at rest. Just a close fit without a seal (.003 clearance) of a tube over the poppet itself should suffice to keep a high level of pressure on the poppet face. The same hat can easily be milled to efficiently funnel air to the power tube inlets, as long as you can ensure the 2 are aligned.

Flowlines are also improved by removing an exposed spring from the valve chamber - those generate turbulence like crazy.

I still maintain that all of those solutions are coming obliquely at the real solution, which is to sequester the air over the poppet such that it doesn't decrease. You're talking about spring to air pressure force ratios without considering the physical meaning:

Air Force is based on chamber pressure, which is lowest as the poppet is resetting, and very high at the start of the poppet actuation.

Spring force is, to some approximation, constant.

Now, since we're not dealing with a balanced valve, the initial air force is pretty much geometrically determined. Adding spring pressure to tune valve dwell down (a direct result of the decreased reset force coming from losing the air force) increases the initial force required to open the valve.

It's clear, then - for a clean signal with high shifting forces in both directions, the easiest thing to do is a valve hat. I suspect that you need a pretty good excess of force on the "valve closed" side of the equation to maintain good efficiency, and assuming optimum flow patterns, one would then adjust to the correct valve dwell by tuning the hammer weight.


I could be wrong, but that's my logical pattern on the matter. I know y0da tried the "slam bolt" which essentially has a pressure ratio (open versus closed) GREATER than 1, and was unable to get velocity. That actually seems an encouraging result to me. My suspicion is much of the flow work that has been done in this thread has the effect of really improving the flow at low lifts, where choking effects at the valve throat become apparent. Unfortunately, without a proper sense of dwell control the cart is well before the horse.
__________________

running it same as yesterday, pressure raised to 575 psi. This brought FPS up to 315, so I added a red valve spring behind the poppet, as well as the cone spring/oring/washer. Yeah, that's right. Two valve springs.

Note that the following numbers aren't with a 12 gram, but from bulk co2 through the Stabilizer. I also replaced the Stabilizer's piston oring as it was looking pretty sad. That may have contributed to inconsistency yesterday, although I only noticed it sticking once I raised pressure past 550.
265
269
273
273
275
275
278
267
268
272
274
265
257
277
270
271

15 shots, average 270 FPS, standard deviation of +/- 5.5

This is a medium weight mainspring that I'm using, nothing super heavy. It's slightly lighter than a standard Blue Maddmann mainspring. This valve is flowing ridiculously well. Two valve springs and a fluted hammer at under 600 psi, and still getting 270 fps.


I just tried to raise pressure past 600. Velocity peaked and dropped down to about 250-260 fps.

Looks like the sweetspot for this valve is right around 575 psi. At least, that's the sweetspot with the fluted hammer and double valve springs...

Opened her up and the cone spring was kinked again. That little tail on the end didn't stop the washer from blowing up and into the spring. Reseated the spring and velocity seems to be around ~290 @ 625psi, using the same fluted hammer and double valve springs.

cone spring kinked again. I removed the washer and oring, leaving the spring. velocity is now over 300. @625psi.

just discovered that the brass poppet sealing face from inside a Tippmann CVX valve fits perfectly to replace the blowby oring and washer. It snapped into place pretty nicely, so hopefully it'll stay put. FPS is now 285 @ 625 psi with it in there.

Bumped up to 650 psi. FPS is sitting in the 290s now. Wish I had a slightly tighter bore barrel...this paint would probably be more consistent a couple thou tighter.

Well...that brass poppet didn't work. It still blew up into the cone spring and got tangled up. I've now got it on the small side of the cone spring, towards the front of the gun. This way the valve throw isn't excessive like when I just removed the oring and washer entirely, and we won't get kinking of the cone spring. In fact, valve throw is barely enough to fully clear the ports right now. This added more tension to the springs, so I had to swap the red valve for a blue. I'm getting around 280 fps @ 650 psi.

Before anyone asks why I'm not using lighter mainsprings, generally heavy springing keeps bounce to a minimum. Heavy springs all around should help get a consistent impact with the light hammer, and keep the dwell very low. Plus, I don't have a green mainspring kicking around, and cutting springs made things bind up to the point I felt it would affect consistency.

12 gram testing will have to wait...it's getting a little late to be shooting now. I think I'm getting close to the sweetspot of this valve, but I'm also getting close to the max output of the PPS Stabilizer, which should be 700 psi.

I'm really looking forward to trying a LP version of this valve. IIRC the newmaticarsenal valve had some flow issues because of the ball end mill size used to form the cup? I think y0da's valve is making a very good case for optimizing flow around the cupseal. It's really incredible how much velocity I'm able to get out of this valve with excessively heavy valve springs, light hammer and low(er) pressure.

My door is always open - I'd be happy to collab on this, I think the money combination is a valve hat, extremely light valve spring, regulator, and higher flowing valve. There is not much of a point selling a maximum performance part to a crowd that isn't using regulators, IMO. Besides, increased closing force isn't really that helpful in a high pressure pump.

Design Notes for Open sourceness:
Quote:
Originally Posted by notes
valve hat extension = .13 + .03 for sealing chamfer

Nut wall to front wall = .92"


Ideal valve lift = .16

lurker cupseal diameter = .28125
lurker cupseal enclosed length = .308
Valve body diameter = .513

Powertube - account for length difference between valve nuts (or, make new lightened hammer to account)
Otherwise the stroke of hammer is shorter. Maybe not an issue.

Hat - add to cupseal, length to be offset in valve chamber


spring - 9657K66 compresses to 34 % of length





so .16 travel
spring length equals dead length plus travel
dead length = .34 travel

call travel .17 to be safe

L = .34L + .17

.66L = .17

L = .257" space for spring

.038 of poppet distance nests with spring


BASE OF VALVE TO HAT = .697


Whipped this up real quick tonight, but I can't decide if I want to match the powertube slots or what. The fact that the powertube TAPERS for a normal valve to increase flow is messing me up. The Phantom slots are of radius 0.0455 with a center length section of 0.0350"

Total port width = 0.091"
Total port length = 0.126"

Provisions for fixing the hat position relative to the front wall are still needed, but are easy. I want to eliminate the sharp edge at the hat front for flow rasons, but I just wanted to give an idea.


You can get away with a considerably shorter hat if you're willing to make the delrin/PTFE thinner. Spring ID right now is right on the 3/16" mark. If you look at springs that fit hole size of 9/32" (the poppet diameter), you can get a much more compact and concentric package.

Ideally, something in 0.022" wire and 9/32 hole fit would exist, and you could use that. (spring then sits concentric to the threading)


Hrm, magnets would not be bad in this application actually. All I want is the valve to not be open at air up, really

Axel is correct in all of his comments.

Step 1: separate the body from the trigger frame by removing the main body screw and valve body screw - both should be Phillips head screws. Note: do NOT remove the larger Phillips head screw that's right in front of the trigger guard.

Step 2: Remove the two small set screws that secure the valve body to the main body of the gun (if they are still there - I can't tell from the photo).

Step 3: Remove the valve body.

Step 4: Unscrew and remove the valve assembly from the valve body. Check to see if the cup seal and valve spring needs to be replaced. Make sure that the valve tube is tightly screwed into the cup seal. You can use pliers for this but DO NOT overtighten, or the valve tube may snap at the threads on the bottom.

Step 5: Thread the valve assembly into the back-bottle ASA adapter.

Step 6: Insert the back-bottle ASA adapter into the main body and secure with the two small set screws.

Step 7: Reassemble the main body with ASA to the trigger frame, and you're done. As Axel stated, you can now use any ASA-compatible system to gas up your gun - AGD Micro CA II, AGD 6-pack, CCI bucket changer, etc, etc.

Note that if you want to remove the internals from the main body you need to see if the bottom rear of the Nel-Spot body has been slotted or not. Given the amount of modifications done already to this gun, I would assume it has been slotted. If it hasn't, then you should make the modification yourself.

On factory Nel-Spots, the body was designed so you needed to punch out the sear retaining pin (from the hammer) in order to remove the hammer, main spring and bolt from the body. Once all the internals have been removed, take a Dremel tool with a cutting wheel and carefully cut out the metal in between the slot and the back of the gun. Basically, you are continuing the slot so it extends out the back of the body (where the valve body connects). It's an extremely easy mod to make, and makes dissassembly of the gun much easier. If the gun has already been slotted, then don't worry about it.

BTW, the old Nel-Spot looks pretty good for it's age. Seems like someone took their time with it. The CCI feed block mod, and addition of the Line SI pump are nice - especially if the body has been "double-slotted" to accommodate the later model dual-arm Bushmaster pumps.

The big question is how far over the barrel does the pump extend? You may want to consider a new barrel as the bore of the old ones are going to be way too big for today's paint. Depending on the age of the body, this could be an extensive/expensive mod to make.

I have a 007 Nelspot for sale. It has a ton of upgrades:
-Battle Grips
-plastic pump handle
-lapco adjustable bolt
-lapco lightened hammer
-large bore power tube .190" ID
-BBA valve and stock in-handle valve(needs a new CCI piercing seal)
-large, 1.5" diameter knurled speed knob (not pictured but I can get more)
-CCI trigger shoe

Now all I need are these things:

Adjustable anti-kink bolt, LAPCO Ultralight Hammer 34 gram, LAPCO #6 Jet Set, Complete set of springs


maybe a barrel also...not sure how that works??????...any sugestions?

Hey thanks for all your help....I got a grey ghost lapco bolt for it (I hope it is adjustable...I know it will fit)....and a light wieght hammer.....I got some info that I should use a #4 instead of a 6 becuase a 6 tends to break paint..

I also bought a jet set....I read to get it so I bought it...I have no Idea what the heck it is....but I guess we will see....now all I need is a #4 power tube and a speed wheel

a speed wheel is a knob that replaces that ring to tighten down your twelve gram


I also turned down a 14 inch Jacko barrel from an angel and cut it to about 11 inches...then put a counter sink on it...and replaced the stock barrel with it


this gun is going to be sweet...I need to pick a color to paint it.....maybe grey....or just a wet black....we will see I guess...I will post a pick once it is all done....and a list of what is on it...but here is the planed up grades:

11 inch infinity barrel (black ano)

Lapco Grey Ghost Bolt

Lapco light weight hammer

Jet Set

New Springs..(maybe the Evo X...Nelson style springs)...STILL NEED

Battle grips

# 4 Power Tube (Carter or Lapco hopefully) ..STILL NEED

Rear ASA (have) and go with the Cooper T quick changer..KNOW WHERE TO FIND...if I go this route I won't need the speed wheel that is so hard to find

I think that is pretty much all I can possibly put on it really
I am going to paint the frame (which has almost no rust)
Paint the Body (needs alot of work...what is the best way to get the rust out of the inside?)

I am going to leave that part that goes on top of the frame and between the body alone....becuase it is in perfect condition...IT STILL HAS ALL THE STICKERS!!! and no rust

again thanks