ATI Libert/Freedom Custom valve

[AVS Stephen]

i have thought of something like that also but all the way to the pellet. see drawing below.

i think your idea is more doable. i can mill that radius on the rotary table to a perfect round smooth radius with a ball mill. the only thing is the valve need be cut in half before milling. two problem arises.
 1) the counter sunk seat.
2) the sealing oring on the OD of valve.

remedy for problem 1 will be to epoxy the valve halves and machine a separate seat and epoxy that in so there wont be a leak through the cut surfaces. the cut lines in the oring groove can probably be epoxy too.

my idea can be used on a custom receiver it self with some extensive sealing technique of the halves.

this will challenge my zeroing and truing techniques on the mill and lathe...i wonder if it can be replicated to produce many more like it or just a one of a kind

Yes, I too thought why not just have a solid stainless steel tube arched from the air tube plenum to the Barrel breech end. Then just place that U-Tube (no pun intended) into a breech that could except various U-Tubes of different inner diameters based on the Caliber and/or Weight of pellet/slug you'd like to shoot.

Duy, you can do it.

[Missed-Em]

Ouch, my head hurts!

[USAFANG6799]

Stephen - Pictures please because it's Sunday and since it's HOT here my brain is cooling off at the beach 

[darkcharisma]

Get to know your edge finder and dial indicator real well my friend! lol

You know, I always thought a pellet was suppose to shot out of a straight barrel? 

you know how our pellets will "curve" left or right on their own free will? this is the curve counter LOL. what you saw is actually the whole transfer port, the pellet drawn seated in a transparent acrylic barrel. 

its too easy to make those smooth transitions in a mill, so i left all that operation for you guys to tune, mod and as a marketing gimmick. you screwed up, or misplaced it, you buy another. you tamper with it, you risk safety on your own. on that note, please dont go crazy and shave too much into the oring groove.

Stephen thats not a bad idea, replacement u tubes. if i decide to make this, ill tackle the permanent tubes first and seal it. ill make as large as possible for .25 caliber then replacement tubes in the receiver

it will be a reversed poppet stem like the Impact so there wont be a stem inside the Utube. and a probe like the bulldog with no push pin rods but a halfmoon cut in the center....
 

[rsterne]

The area of a 0.255" throat obstructed by a 2mm (0.079") stem is the equivalvent of a 0.242" hole.... That is about 12% larger in diameter than your 0.217" port, which should work just fine.... I usually aim for the throat to be about 10% larger in equivalent diameter than the port, so you are right on the money, IMO....

Bob

[darkcharisma]

thanks Bob, can you please tell me how to calculate that?

.242 is ready for .25 caliber i think 

its in the plans guys

[screwwork]

https://www.gatewaytoairguns.org/GTA/index.php?action=dlattach;topic=156725.0;attach=267550
Let's see if this works? It works, click on the link and it should download the file for you.
If it doesn't work search (porting spreadsheet) to find the ink.

[darkcharisma]

thanks Randy but i am trying to see what Bob does to come out at .242 with .255 throat and .2mm stem. having a formula so i can do other calculations later on.

[screwwork]

The area of a 0.255" throat obstructed by a 2mm (0.079") stem is the equivalent of a 0.242" hole.
using the porting spreadsheet.
Caliber for comparision (dia) enter .242, that equals 0.0460 area.
Throat area poppet stem od is (0.078 or 2mm) area (0.0048)
Throat ID is .255 area (0.0511)
The Sum of the poppet stem & throat ID is 0.0463 area is equal to 0.242 dia hole.
Does that make sense now?

[screwwork]

Your smallest port is .187 and any port larger than it doesn't improve the porting. All ports; Barrel, Transfer Port & Valve Port should either be the same diameter or equal in area. With .217 valve exhaust port the transfer port should be .217 dia and the barrel port at .187 x 0.03 oblong to .218 long slot is equal to area of 0.0332. The smallest port is oblong barrel porting is 68% of the caliber. It is truely a balancing act to get the area equal throughout the Barrel, Transfer Port & Valve ports without having custom retractable bolts like Bob makes on his guns.

[darkcharisma]

My smallest port on my personal gun is .217 from exhaust to barrel  . and i am in need of the bigger plenum which i received from Billy. Thanks Billy!  much better than my crude plenum which failed at the threads. time to show some test results with the plenum later on.

now it makes sense, i didn't know how to convert back to radius and diameter. time to ramp up on math too i guess

[darkcharisma]

got some numbers from Matt with the old one hole exhaust port with 10degree angle

everything oem settings and no ports

first test: filled 3200 shoot to 2700
14.3grains were in the 1150fps average. 12-15 shots. lots of air loss
28.6 grains were doing 820fps at 2500psi

second test: filled to 3200psi
28.6 grains were going slow in the 550fps and climbing as pressures drops

he dropped pressure in tube to 2800psi and 28.6 grains were going 675fps.

shot 14.3 grains from 2800 to below 2000psi. some 27-30 shots. 980-1050fps...wild spreads. finally last shot dumps all air out due to hammer resting on long stem as pressure drops below 2000psi. i am guessing 1700-1800psi when it dumps

anyway. this tells me the regulator is doing something funky when the big valve is introduced. tesing inconclusive and was not able to replicate the initial 1150fps. we need a gauge on the reg. and more testing

[Madd Hatter]

Duy, that looks similar to what I was seeing. IMHO I really think the longer stem is part of the problem. It seems to me there isn't enough distance for the hammer to get any momentum but what do I know?

[darkcharisma]

hey Robert, have you grind that stem down yet?

i made it long so it would be easier to go short later then to have short to can't go long if needed.

i recommend comparing both oem and the 2mm stem and grind and polish the 2mm just a 1/10 of an inch longer.

i dont know more than any of you. i am just free styling on the lathe with approximations. i hope someone has an equation for the 60fpe i am chasing. i can provide the details...anyone? (Bob) (echoing...bob) 

BTW i just measured the oem plenum with fluid. it is 5.2cc+the 3cc in the breech. wow thats tiny.
 Billys plenum alone is 15.2cc+3cc for total of 18.2cc. respectively doubling the total cc. i cant wait to test it

just a teaser, here are the pictures...😆 i think this plenum is made in heaven for the big valve.

[huklbery]

Moving along with making experimental plenum extensions.  Held air last night as a plug (need to pay more attention to oring sizing as I have a nice bag of 16mm id)  Hope to be able to test across the chrony this week.  I'm looking to roughly double the volume, if that makes a significant gain go from there. 

[Heath]

Is it just me and my experience or is get replacement parts from American Tactical difficult if not impossible. I have ordered 3 guns from them, 2 Nova Liberty's, 1 in wood and 1 in Synthetic and a Nova Freedom I bought for basically parts if it’s not fixable. I have given a guy by the name of “Ty”, who by the way seems to be the only person there at least the only one I ever seem to get ahold of anyway. I have given him all the part numbers at least twice and since placing the order for the parts which all 6 would fit in an envelope, a small envelope, have gotten 2 other guns in the meantime from them. Still no parts. I kinda feel like I bought a car and can’t get parts for it. I ordered a power adjustment stem, the small spring and 2.5mm steel ball, basically everything but the small pin that’s connected to the power adjustment valve stem. I made one out of 316L a while ago but want the original back because I’m gifting the rifle off to my grandson and he is not ready for a full power air rifle. The valve I made puts the gun with 15 grain pellets in the mid 40 FPE range and I feel that’s too much for him and don’t have the time to make another valve stem. If anyone has any other places to get a factory power adjustment wheel please let me know. You guys rock and thanks for all you do to help this way of life keep being awesome.

[FuzzyGrub]

Is it just me and my experience or is get replacement parts from American Tactical difficult if not impossible. I have ordered 3 guns from them, 2 Nova Liberty's, 1 in wood and 1 in Synthetic and a Nova Freedom I bought for basically parts if it’s not fixable. I have given a guy by the name of “Ty”, who by the way seems to be the only person there at least the only one I ever seem to get ahold of anyway. I have given him all the part numbers at least twice and since placing the order for the parts which all 6 would fit in an envelope, a small envelope, have gotten 2 other guns in the meantime from them. Still no parts. I kinda feel like I bought a car and can’t get parts for it. I ordered a power adjustment stem, the small spring and 2.5mm steel ball, basically everything but the small pin that’s connected to the power adjustment valve stem. I made one out of 316L a while ago but want the original back because I’m gifting the rifle off to my grandson and he is not ready for a full power air rifle. The valve I made puts the gun with 15 grain pellets in the mid 40 FPE range and I feel that’s too much for him and don’t have the time to make another valve stem. If anyone has any other places to get a factory power adjustment wheel please let me know. You guys rock and thanks for all you do to help this way of life keep being awesome.

I'm actually surprised that ATI took an order of parts.   Can you share what parts and prices they quoted?   

Now, ATI, as to last I discussed with Ty, did not have any spare parts on hand, including poppets, which I thought would be there by now.   I don't know what kind of a import cycle they are on, but the parts would be packed in the next container. 

I've mentioned this before, I think it would be great if NV sold the parts direct on AliExpress.  My guess is that it violates something in the contract with ATI.

[FuzzyGrub]

i dont know more than any of you. i am just free styling on the lathe with approximations. i hope someone has an equation for the 60fpe i am chasing. i can provide the details...anyone? (Bob) (echoing...bob) 

BTW i just measured the oem plenum with fluid. it is 5.2cc+the 3cc in the breech. wow thats tiny.
 Billys plenum alone is 15.2cc+3cc for total of 18.2cc. respectively doubling the total cc. i cant wait to test it

just a teaser, here are the pictures...😆 i think this plenum is made in heaven for the big valve.

From reading many of Bob's threads, he generally likes 1cc per fpe.  My experience with in-tube regulators in Mrods/pellet shooters is that 1/2cc per fpe is sufficient, but does require a higher set-point.  With the Liberty, and its high fill pressure capability, we can raise the set-point even higher.  I think you were hitting 50fpe before, so the new plenum won't be holding you back. 

[USAFANG6799]

Is it just me and my experience or is get replacement parts from American Tactical difficult if not impossible. I have ordered 3 guns from them, 2 Nova Liberty's, 1 in wood and 1 in Synthetic and a Nova Freedom I bought for basically parts if it’s not fixable. I have given a guy by the name of “Ty”, who by the way seems to be the only person there at least the only one I ever seem to get ahold of anyway. I have given him all the part numbers at least twice and since placing the order for the parts which all 6 would fit in an envelope, a small envelope, have gotten 2 other guns in the meantime from them. Still no parts. I kinda feel like I bought a car and can’t get parts for it. I ordered a power adjustment stem, the small spring and 2.5mm steel ball, basically everything but the small pin that’s connected to the power adjustment valve stem. I made one out of 316L a while ago but want the original back because I’m gifting the rifle off to my grandson and he is not ready for a full power air rifle. The valve I made puts the gun with 15 grain pellets in the mid 40 FPE range and I feel that’s too much for him and don’t have the time to make another valve stem. If anyone has any other places to get a factory power adjustment wheel please let me know. You guys rock and thanks for all you do to help this way of life keep being awesome.

I'm actually surprised that ATI took an order of parts.   Can you share what parts and prices they quoted?   

Now, ATI, as to last I discussed with Ty, did not have any spare parts on hand, including poppets, which I thought would be there by now.   I don't know what kind of a import cycle they are on, but the parts would be packed in the next container. 

I've mentioned this before, I think it would be great if NV sold the parts direct on AliExpress.  My guess is that it violates something in the contract with ATI.

One would think that since the GTA community is global that we could gain some more insight as to what's going on behind the scene. It's locked down pretty tight as it seems. That's why I think there is some business dealing going on that we are not privy to.

[Madd Hatter]

hey Robert, have you grind that stem down yet?

i made it long so it would be easier to go short later then to have short to can't go long if needed.

i recommend comparing both oem and the 2mm stem and grind and polish the 2mm just a 1/10 of an inch longer.

i dont know more than any of you. i am just free styling on the lathe with approximations. i hope someone has an equation for the 60fpe i am chasing. i can provide the details...anyone? (Bob) (echoing...bob) 

BTW i just measured the oem plenum with fluid. it is 5.2cc+the 3cc in the breech. wow thats tiny.
 Billys plenum alone is 15.2cc+3cc for total of 18.2cc. respectively doubling the total cc. i cant wait to test it

just a teaser, here are the pictures...😆 i think this plenum is made in heaven for the big valve.

Not yet. I know, I know, get off your duff McDuff and get busy!! lol Since the original plenum is giving in the mid 40's or higher I think (?) you should be able to get the 60's you're looking for but again what do I know.