On / Off pin Valve vs. Bearing Driven Valve

[Jack & Coke]

From: http://www.automags.org/forums/showthread.php?s=&threadid=101941


Originally posted by Hoplon



Originally posted by RenagadeOfFunkRTPcf
HAHA FREAKING TIMMY RIP OFFS!! YOU DONT SEE ANY MAG RIP OFFS DO YOU....YOU WANT TO FREAKIN' KNOW WHY>>>

CAUSE YOU CAN"T DUPLICATE GENIUS!!!! MUHAAHAHH OH, THE POWER OF MAGS!!!

http://www.icdpaintball.com/Support/Desertfox/support-desertfox.htm

After reading this, I learned that the ICD Desertfox uses a different method of shuffing off the main valve during firing mode.

Whereas Automags use an on-off pin / trigger sear:

http://store.airgun.com/agdprod/images/parts/aaRT_Retro_onoff_med.jpg http://store.airgun.com/agdprod/images/parts/RTsear_med.jpg

...the ICD Desertfox uses a "ball driven valve" to close off the valve:

http://www.icdpaintball.com/Support/Desertfox/images/fox-schematic.gif




...This gun has a "blow forward" type of mechanism. The mainspring and sear hold the piston with its piston valve pin in place, in turn holding a bearing driven valve open, allowing pressurized gas to come from the regulator into a forward chamber.

When the trigger is pulled, the sear releases the piston and allows it to move forward to shoot the paintball. The main spring compresses and the bearing-driven valve closes, preventing the further expulsion of compressed gas.

The main spring then decompresses and the piston is moved back behind the sear. The bearing is displaced, opening the valve once again...



It's obvious the blow-forward design of the Automag and Desertfox are similar, but what are the advantages/disadvantages of their different on/off valve designs?

Opinions please...

:)

[hitech]

Off the top of my head the On/Off Pin does not require any springs for return. It provides the return force for the sear. Less moving (i.e. breaking potential) parts.

I'll give it more thought.

[speeddemon]

Looks like the only thing the sear has to worry about is the bolt, which makes me think that this type of valve could have an extremely light trigger pull. Use a LX style bolt with a roller sear (if possible) and I bet you could get truly electric light mech pull.

[hitech]

Is this the marker that Tom said was in violation of his patent? Just curious, doesn't matter for this discussion.

[Marek]

Didn't he put the company out of business by adding a VL 200 to the Classic Mag?

[Jack & Coke]

hehe... I never thought of it that way:

ICD copies AGD => Desert Fox
ICD copies SP => Bushy and BKO

Hmmm...:confused: I wonder if AGD would catch flak if it went after ICD?

But that's for another thread... I'm more interested in how this "bearing driven valve" works and if it's any good?

Before I go asking quesitons over at PBN, does anyone here have any experience shooting and working on both, the Automag and Desert Fox?

[billmi]

I own both.

From a technical standpoint, I like ICD's method - there are no possiblities of timing issues between the on off and the sear grabbing the bolt due to things like paint on the grip rail.

On the downside, the way the air flows around the ball bearing, I'm not sure it closes as consistently as the Automag's on/off. It's definitely been a few years since I had the Fox (read as - I was shooting it on CO2) on the field, but as I recall it wasn't as stable velocity wise as my Minimag.

The ball bearing on/off in the power tube is simpler, but still works.

I don't believe the Desert Fox ever got the popularity the B2K and BK0 have gained, but it was a nice gun to shoot, couldn't be short stroked, and had a cool modular structure to the body.

See you on the field,
-Bill Mills

[Spaceman613]

Originally posted by Jack & Coke

ICD copies AGD => Desert Fox
ICD copies SP => Bushy and BKO



Uh, the bushy was out before the Impulse...

[RobAGD]

BUshies and defiants were out a while before the Imps.

The Bushie, Imp, Timmy, Angel, all are just modified spyders that use the solenoid to drive the striker vs springs.

-Robert

[GoatBoy]

You know, aside from being obviously aesthetically challenged, I've always kind of liked ICD and the thought they put into their products.

Problem is, in all my days, I've only seen one ICD gun, maybe two (I think it was the same guy, which would actually make sense).

I like their on/off design; it's simpler and probably almost as effective.

Strictly speaking, as far as just the on/off + trigger + bolt is concerned (I don't know anything about their regulator), your main trigger actuation is all about whatever is holding that bolt back.

Simply put, it's your finger versus the return spring(s). Are there two return springs in there on that trigger/sear or is that just me?

The problem then comes with reliability of catching a moving bolt which instantly repressurizes because it's slappin da ball on its way back. Note that the trigger isn't controlling the on/off, it's the bolt. It's critical that whatever mechanism holds that bolt in place is ready to catch the bolt as soon as the chamber is repressurized.

On a mag, the two are (supposed to be) linked. The chamber repressurization is mechanically linked to the sear, almost guaranteeing that the sear is ready before the chamber is repressurized.

So it looks like the 'sear' is, in fact, spring loaded on the Fox. I guess that's what's keeping it from double-firing. A strong enough spring on the sear return to make sure it's up when the bolt is back.

FYI, take a look at this:

http://www.cognitivevent.com/icd/fox_tweaks_reg.html


Pros: No chuffing as far as I can tell. Valve design is simply ... simpler. Resultant trigger is probably easier to turn into a hair-trigger since it relies on older methods, although this would probably in the end compromise reliability, like shaving the sear down on a mag.

Cons: More complicated trigger. Rate of fire somewhat limited by the safety zone needed for that spring loaded sear to pop back up. Probably not that much of a limit, but you have to admit, trigger springs suck. Potentially more wear on the bolt. More places for the trigger to wear out. Constant smacking of a piston against a ball. And while I tried to leave the regulator out of this, I bet their system doesn't recharge as fast as an RT. Probably closer to classic AIR levels, if even that.



The way I see it, they traded a simpler on/off for a more complicated trigger.



If you L10'd the bolt, could you get away with a softer return spring?

Probably not. The return spring's job isn't to go up against the bolt. Varying the forward pressure at the beginning of the cycle is fine and dandy, but I don't think that return spring cares. The return spring's job is to get the sear back in place in time. Ah yes, time. What else changes with the L10 bolt? The mainspring. Oops. The bolt comes back faster and harder than it did before, as evidenced by the really annoying mangling of the clear bumpers. You might need an even stronger return spring on that sear for an L10 to get it to catch reliably.

So in a mag, an L10 bolt results in a lighter trigger. On a Desert Fox... A heavier trigger?





Someone (I see Bill posted while I was in the middle of looking at this stuff) tell me if any technical area of mine is lacking. This is all just looking at pictures and waving my hands.




Oh, and guys, the point of the thread isn't "who was first?"

[ezrunner]

I agree with you on the timing of product releases, the IMP was a copy of the bushy w/o an LPR when first introduced.

However, the bushy is a work alike of the angel, not a spyder copy. It still is an open bolt linked hammer design, but I think it deserves more credit than "spyder copy".

The BKO is a work alike of the EM1 that was a half rip of the bushy. Instead of driving the bolt motion each direction with a solenoid, they returned the action with a spring and drove it with the solenoid. This is simpler and less expensive as the solenoid and ram are less complicated and thus lower cost.

I'm not saying ICD is the most original group, but I understand Bob Long had a hand in the design of the bushy (that is why the defiant existed).

The Timmy is the evolution of the design of the bushmaster and works the same way. I'm not a Timmy fan, but the results of the design are obvious when you look at the way kids snap up every new version.

I think that 2 of the best guns in paintball are the Angel and Mag becuase they take the most abuse and are great designs. They last for years and are very servicable.


The bushies are great little guns but like every design they have advantages and limitations.

-rob long

[Jack & Coke]

Originally posted by GoatBoy


...FYI, take a look at this:

http://www.cognitivevent.com/icd/fox_tweaks_reg.html

Oh, and guys, the point of the thread isn't "who was first?"

Great post GoatBoy!!!

thanks!:)




In the 'Classic' Desert Fox (and in the Automag as well) there is another valve downstream from the main regulator valve, called an On/off valve.

In the 98 Desert Fox it has been eliminated by going to lower pressure operation. (Explaining this is like the chicken and the egg problem, they cannot be separated. Bear with me.) In Physics, the gas laws state that to provide equivalent energy at lower pressure, the volume of gas used has to be increased. In the higher pressure Classic Fox an On/off valve shut off the flow of gas whenever the bolt moved forward to make it easy for the mainspring to cock the bolt back to the rear position. The On/off choked the air flow by turning it on and off constantly, but the higher regulator pressure compensated. Since the On/off lived inside the Air Chamber it also reduced the available volume of pressurized air.

In the new 'Fox the regulator output is open all the time, with the flow shutting off only when the regulator equalizes; so the regulator is much simpler and more efficient. Removing the On/off valve combined with changes to the air chamber milling to increase the internal volume of the makes the volume of stored air quite a bit larger. With a larger volume of air available, the energy transmitted to the paintball is increased. So the regulator can be turned down and yet still give 300 feet per second velocity. With reduced pressure from the regulator the back pressure on the bolt is reduced while the air chamber is filling, and the same bolt mainspring can still push the bolt back to latch on the sear. Reliability is increased since there are now fewer seals, and most of the remaining ones are operating under lower pressure.

It may be possible to upgrade an older 'Fox by ordering the new Regulator Valve, removing the On/off, and installing a lockscrew to hold the valve down, but this would be best done by an advanced machinist.

The Tradeoff: (after all, you can't get something for nothing) There may be a very slight slowing of the bolt return due to the pressure of the valve being open. This should be offset by faster recharge since the airchamber starts to fill as soon as the pressure drops, and then stops filling at a lower pressure. Unscientifically, the firing rate feels the same as the older model, and the changes should reduce pressure dropoffs when strings of shots are fired.

The key openings in the 98 'Fox Regulator are the air passages into the valve, the holes in the forward brass Regulator Valve, and the opening at the top of the rear chamber. Using a needle file, you can open up each of these channels, but be careful not to scratch any of the O-ring sealing surfaces, or you'll be buying a new regulator body.

[Jack & Coke]

ICD version possibly an IMPROVEMENT over the AGD version???

From:http://www.pbreview.com/forums/forumdisplay.php?s=&forumid=66


Originally posted by Draknes


...my personal results though:

With my old fox, consistancy was definitely not a problem...

...With a 68/3000 Nitro Duck tank I was getting +/- 2...

...As for the pull, mine was about 3-4 mm and silky smooth :D Unlike a mag, you can't short stroke the trigger and it is a double-trigger stock, so you can easily pull 8-10bps....



No possibiliy of short stroking?
Silky smooth trigger release?
Great velocity consistancy?

Results sounds interesting!
(from a design point of view)

[Jack & Coke]

hmmm... NO on/off?


Originally posted by Draknes


The on-off was attached to the bolt on the older (pre-98) foxes. Since then they have gotten rid of it entirely. On all the newer desert foxes there is no on-off valve.



Without an on/off, I don't think you can have a level 10. In order to the Level 10 to work, the air has to be cut off.

Oh well... I find it interesting how all these different gun designs work and relate to each other. Like comparing a V8 engine to an inline 6 to a Rotary Engine... :)

[GoatBoy]

Originally posted by Jack & Coke
hmmm... NO on/off?



Without an on/off, I don't think you can have a level 10. In order to the Level 10 to work, the air has to be cut off.

Oh well... I find it interesting how all these different gun designs work and relate to each other. Like comparing a V8 engine to an inline 6 to a Rotary Engine... :)


Yeah, this was in that URL that I posted, although I didn't get into it much because regardless of the ball on/off, the effect on the trigger is the same.

The assumptions in the on/off-less design (where the valve is always open) are:

1. You have enough pressure to send the bolt and the ball forward and compress the mainspring when firing.

2. Afterwards, the spring releases its energy, which was hopefully enough to send the bolt back and close things up while the dump chamber is constantly pressurizing.


In the end, if you think about it, the L10 WOULD work on the fox, and in fact it might help it work better. In the event that the mainspring might not pick up enough energy to send the bolt all the way back -- it starts going back through it's sealed power phase... and then into the patented Level 10 venting area. I.e. it would let off a little of the pressure in the dump chamber, and the spring might then have enough energy left to send the bolt all the way back after letting some of the pressure go. But, this sort of sends you backwards in the design, because they did the on/off-less design to make it recharge faster, but then you just let some of the pressure off coming back, so now it has a little more to recharge.

In an anti-pinch scenario, however, I dunno if the spring would have picked up enough energy to send the bolt back, like you said, since the on/off would preferably be shut off.

Twisty, huh?


The pbreview guy's experience seems to correlate with what I said earlier.



There is one thing about the design which can be fatal, as indicated on that 'Fox webpage I linked. You're counting on this dueling banjo's see-saw kind of action with the bolt and the pressure. So what happens if your bolt gets caught in equilibrium limbo, for whatever reason:

http://www.cognitivevent.com/icd/fox_trouble.html#cycle



'There can be several causes for this problem. The symptom is that the bolt doesn't cycle completely, coming to rest beyond the sear and partially obstructing the powerfeed. I've had balls even partly pinched between the feed intake and the bolt putting a dent in them. If this happens you are really PUCKED if the game is on - FIND A SAFE SPOT TO HIDE to work on the gun. You may have gunk in the gun obstructing the bolt travel or you could have insufficient pressure when firing which doesn't compress the main spring enough allow the reset of the bolt. You may even have a small double fire where the bolt fires, cycles and an automatic second pop pushes the bolt forward past the sear again - but not cycling completely.


You are reeeaaalllyy screwed. Think of it almost like when your L10 is out of tune and doesn't reset -- it just sits there in the middle. It might not be too common an occurance, except when you start chopping balls and getting obstructions in your chamber. After all, they don't have an L10 for that thing :)



It's an interesting design, and I'm sure it suits plenty of people's taste in paintball guns.















So Jack, were you the one playing with the sear leverage modification? I'm really curious about that one. I don't particularly care for a chuffing ULT, but using it to reduce trigger length and chuffs... that's a winner in my book.