Tale of THREE BRods - .25, .30 and .357 Completed, Page 19 !

[MJP]

Thanks Bob,
I was comparing the cothran and art valve to fury valve, and there I have a point where the valve will cycle fully open or just a little pop. It blows open when opened past some point. That margin is Very narrow, just as simple as hammer cocking lever rubbing slightly against the frame and it did pop and nothing more. One 2mm shim sorted that problem.

I know how the Travis has built the valve, and how Cothrans valve is made, my valve is alot similar to that, minus some parts and something modified.

The ability to tune the art valve for smaler bore guns is very good, and I can see why.
I would say for all around valve the adaptability of The Art valve is the best in the market, it suites small and medium bore guns.

I'm interested how well it will scale up to the big bores...
Keep up the good work guys!

Marko

[oldpro]

 Marko it works well with any bore size you just have to scale up the piston diameters. It almost doubled the FPE of the Bulldog 357 and increased shot count by a good margin when tuned back to stock power levels. Give it a go Marko when your caught up with schooling your one of a few who have actual knowledge of the internal workings.

[MJP]

Travis, as soon as I'll have the Emco Cnc turn up and running, still waiting for the darn chuck to be delivered.
I will give it a go, and you will be the first to know.
Too little time to be standing at the lathe turning, so the cnc will definitely help with my testing different designs.

Its the little parts that take most of the time to turn, taking small cuts with a manual lathe is very time consuming, right Bob?

Spring period will be more easier for me, for I have experience on most of the courses and dont need to attend as much. Mostly material and manufacturing technology, 10 years as a machinists and welder gives me a slight edge over the youngsters. 

Marko

[rsterne]

Tim, here are five more data points for you.... I extended the striker 1/8" on the 27 gram hammer, so the hammer stroke (no gap) is now 0.66"....  This data is for the .30 cal, with 49.7 gr. pellets, at 1900 psi.... The zero gap starting point is, of course, 1/8" further out.... Also, spring preload has been reduced to 0.35" (~2.8 lbs.)....

Zero gap = 950 fps
1 turn gap = 935 fps
2 turns gap = 890 fps
3 turns gap = 820 fps
4 turns gap = ~ 300

Looks like the shorter hammer travel (and slightly reduced preload) moved the cliff another couple of turns closer to zero gap.... I would not move it any further, so this setup looks about optimum to achieve the desired tuning range without having too much gap....

It is important for everyone to realize that my ART/SS valve is NOT stock, it has a 1/4" exhaust port instead of 3/16" and currently is running no jet in the inlet (ie wide open).... I am interested in power over efficiency at the moment....

Bob

[shorty]

Bob, thats great you have a striker on there. With the such low cracking force of the valve and using a shorter stroke looks like it should be advantageous in couple ways.

Reducing the preload as you mentioned.
Less cocking effort.
Moving the cliff to allow for more adjustability ( fine small adjustments will make big swings )
Possibly helping with the valve running away when fired below regulated set point.
Faster lock time with such low hammer spring.

Even though you are doing this all with the hammer and spring power plant, I have a feeling that the jet helps tunes this out smoother for a more manageable adjustment through out the hammer spring setting and hammer weight.

[rsterne]

I like preload (with a gap), it is part of the SSG concept, and reduces cocking effort compared to equal hammer energy with an SSS (and I would not use a conventional preloaded spring with this valve).... Actually reducing the stroke would require more preload, or less gap, of course.... Cocking effort is already a joke, you certainly don't need to reduce it further.... I have requested Travis send me a stock MRod spring to try, that will be PLENTY, pretty good when you are talking a 90-100 FPE in .30 cal.... The valve now has ease of adjustment, one turn of gap changes the velocity between 15 - 70 fps.... and you can easily make 1/12 turn adjustments visually with a hex head on the gap adjusting bolt.... put a mark on one point of the hex, and think hours on a clock.... The lock time is already VERY low because of the 27 gram hammer....

As far as the valve "running away", I haven't seen that even with lots of preload.... which is the same as running lower pressure than the tune is for.... Yeah, it uses a ton of air, but that is because the preload is resisting the low closing forces on the valve.... I have NEVER seen any tendency towards valve bounce, or "machine-gunning" at any setting, and certainly not with a gap in the SSG....

I don't have enough experience with changing the jet (two data points, small and way too big).... However, from that small amount of data, and talking to Travis, it seems that a smaller jet gives you a wider velocity adjustment range between the plateau and the cliff.... My worst case was only 60 fps (low preload, no jet).... most run about 100-120 fps, with heavy bullets running closer to 150 fps.... Compare those to a Cothran where if you dial it down only about 40-50 fps, at which point you get a huge ES, and then the cliff.... Travis says that in smaller calibers, with smaller jets, you can get about a 300 fps adjustment range....

Why would you ever need more?....

Bob

[shorty]

A good example of wanting more would be your 25.39 testing vs 34 grain shooting at 1900 psi (25 cal). You can not have both of the best speeds for accuracy without changing anything else except a hammer spring adjustment.

I am learning as much as I can from your testing in the hopes that someone does not have to put all that money and time into additional parts to allow the valve to work more traditionally with such a low cocking effort ( a nice happy medium ).

Not too many people do what we do and may get disappointed if they just dropped this valve in their gun with no other "part" changes.

The runaway part is important to understand (too me) because I am now running un-regulated. I also run tunes from 1500psi down to 1000psi goofing around with 50 fpe tunes. But, then I like to charge to 3000 psi and shoot down to 2300 psi for 80 fpe tunes. I hate taking the gun apart and I am sure other people do too, so all I have to do is adjust my hammer spring adjuster.

The comment amount the smaller port makes sense (smaller more range) but, I have a feeling it also changes the cracking force which in turn allows for different hammer and hammer spring changes making act more similar to a conventional valve. I could be wrong though and the port does other stuff like changes dwell. I have no idea.

[rsterne]

OK, I understand.... you want to be able to change ammo and shoot both in the 900s with only a hammer spring preload change.... On a regulator, you can do that with a conventional valve, with a Cothran it is out of the question.... I don't know about a stock ART/SS, because I never tried that.... When I develop a gun, I have an idea what I want, and once tuned I never change either ammo or velocity.... So far, though, I haven't seen anybody "disappointed" with the new valve.... 

If you are running unregulated, as long as you have enough power to shoot the 34 gr. at 70 FPE within allowable fill pressure.... then you can easily shoot the 25 gr. at 50 FPE (or less).... by just dropping the fill pressure.... You may not even have to alter the preload/gap....

If you have an externally adjustable regulator (yes, they are around).... then you can do whatever you want, from basement plinking to max. power.... with any suitable weight ammo of course.... Lots of ways to skin a cat.... 

Bob

[oldpro]

A good example of wanting more would be your 25.39 testing vs 34 grain shooting at 1900 psi (25 cal). You can not have both of the best speeds for accuracy without changing anything else except a hammer spring adjustment.

I am learning as much as I can from your testing in the hopes that someone does not have to put all that money and time into additional parts to allow the valve to work more traditionally with such a low cocking effort ( a nice happy medium ).

Not too many people do what we do and may get disappointed if they just dropped this valve in their gun with no other "part" changes.

The runaway part is important to understand (too me) because I am now running un-regulated. I also run tunes from 1500psi down to 1000psi goofing around with 50 fpe tunes. But, then I like to charge to 3000 psi and shoot down to 2300 psi for 80 fpe tunes. I hate taking the gun apart and I am sure other people do too, so all I have to do is adjust my hammer spring adjuster.

The comment amount the smaller port makes sense (smaller more range) but, I have a feeling it also changes the cracking force which in turn allows for different hammer and hammer spring changes making act more similar to a conventional valve. I could be wrong though and the port does other stuff like changes dwell. I have no idea.

You need to work with a balanced valve at least once Tim your understanding of the parameters is limited and making assumptions based on no actual data of your own makes you look like your trying to force certain parameters of a conventional valve to work with completely different technology. But for 30 cents you can make a SS valve work just like a conventional valve.

[shorty]

Yup. Your probably right Travis but, I am learning so much from Bob about how to and not how to use a "balanced valve" properly. Knowing that the SS valve can be used as a conventional valve too is a plus. Is it just closing off the jet ?

Have been trying to wrap my head around the cliff and the adjustability through the plateau (on/off opening).

Been running spring calculations this morning to try and get a better understanding. It would appear, that using a balanced valve, it is nearly imperative to run a SSG due to how the SSG set up with a preload leans out the spring rate curve. And, by using any kind of SSS would be extremely touchy. An SSS would have a very narrow plateau and can over power the balanced valve (creating that run-away).

I wouldnt have believed it until I put the tables together and charted them. I am super interested now about the comment that the cothran valve is slighter harder to open and has a shorter plateau than the SS valve but had a higher efficiency. I had to go back to the beginning of this post to see what SSG was used. Big difference from a 12Lb spring to 8 Lb spring.
It would be interesting to see how the cothran valve would fair with the identical SSG set up/hammer weight as the SS valve. I am not asking to do that because you have done so much already but, it sure would be interesting.

Going to the 6lb/in spring with a 3.2lb preload looks like it will be the ticket to extending the plateau, being able to use only .015"/.02" gap would be nearly full open on the valve.

I hope I am learning something here. Thanks for sharing all the information (and putting up with dumb questions and comments).

[rsterne]

I tested the Cothran valve in the BRod using the SAME setup as the ART/SS valve, same spring, same preload and it was harder to open.... You must have missed that.... Reply #233.... The cliff occurred at about 3 turns less gap with the Cothran....

Bob

[shorty]

Yeah I missed that. I thought during that time the jet size in the SS valve was .0344" and not the later tuning with .06"/.125 wide open. I was looking at the last round of testing when you removed the jet on the SS valve to allow it to open easier and have a shorter plateau.

"Jet removed for remainder of .30 cal testing.... Preload 0.40" (3.2 lbs).... 34.1 gr. @ 1900 psi....

With original 51 gram hammer.... plateau velocity = 960 fps @ 2 turns gap or less....
4 turns gap = 957 fps
6 turns gap = 940 fps
7 turns gap = 925 fps
8 turns gap = 896 fps
9 turns gap = 330 fps"

[rsterne]

Your table above is still done using 0.68" of hammer travel, which is incorrect.... so you can't rely on that table and chart as I said before.... The hammer travel was 0.79" for everything except the last run with the 27 gram hammer with the striker adjusted out 1/8", where the travel is 0.66".... In addition, the yellow highlighted cells in your table for the two preload condition on the 8 lb/in valve are both at the same gap (4 turns).... The proper comparison would be to use 1 turn less gap for the 0.040" preload, comparing them at the same gap is meaningless....

Here is the raw data for the Cothran valve.... .30 cal. 49.7 gr. @ 1900 psi.... 0.40" preload, 8 lb/in spring, 51 gr. hammer and 0.79" hammer travel....

Zero gap = 953 fps
1 turn gap = 950 fps
2 turns gap = 947 fps
3 turns gap = 907 fps (ES > 50 fps)
4 turns gap = 372 fps

Reducing the preload on the SSG from 0.60" to 0.40" moves the cliff 1 turn, so for a direct comparison with the SS valve, at most the cliff on the above Cothran run would be at 5 turns gap with 0.60" of preload.... That compares to the cliff being at about 9 turns out for the SS valve with the same configuration.... In addition, the Cothran has virtually no USABLE velocity adjustment range, it has a plateau and a cliff.... The 907 fps at 3 turns of gap (above) with the Cothran came with a ES of over 50 fps.... Also, I didn't "remove the jet to make it open easier and have a shorter plateau", I simply did it to see what effect that would have.... It actually didn't change the position of the cliff, it made less of a "knee", reducing the velocity adjustment range available.... The valve acted a bit more like the Cothran valve when I removed the jet (although maintained some adjustability).... It didn't increase the maximum power, although it extended the plateau to greater gap, and in fact I can't really see any "advantage" to removing it (which is just what Travis said, surprise-surprise).... He maintains that using an even smaller jet will allow an increase in the velocity adjustment range....

I see no reason you could not use an SSS with the ART/SS valve, but "Stiff" will take on a completely different meaning, as it might mean a 10 lb/in spring instead of a 6 lb/in spring using an SSG.... The problem I could see that using an SSS with a spring that soft may allow it to absorb energy on the rebound and bounce, but only trying it would tell you.... The alternative, if you insist on using a very stiff spring, would be to drastically shorten up the hammer stroke, so that the SSS isn't compressed very far when cocked.... I would think that would make it extremely sensitive to adjust....

You keep referring to the valve "running away" when the pressure is drastically below the tuning point (eg. below regulator setpoint).... and I have repeatedly asked you to clarify, but you just keep insisting that is a problem.... I don't get it .... You haven't used an ART/SS valve, so what are you basing that comment on?....

Bob

[shorty]

The run away started with Dairyboy with a complete dump around 2000psi. The second was with PCPshak (sorry if that the wrong name but it's what I remember). The last one was with Motorhead making the comment that his ran away too.
In PCPshak's case (sorry for the name again), his was extremely dangerous as it extruded his shroud and locked his LDC on to it.

Now these guys are not knuckle heads and know how to tune.

So yes, I am concerned that if I buy a valve and don't know enough about it that I will either damage or hurt myself or someone else. Just wanted to fully understand what I would be getting into if I bought a SS valve.

I can see that your getting aggravated so, I will show myself to the door and avoid conflict. I thought I could use some of your information and ask questions since there is nothing out there in regards to what happens if you do this or that with the valve and your information has been more than anything since and before the valve has been launched.

[oldpro]

The run away started with Dairyboy with a complete dump around 2000psi. The second was with PCPshak (sorry if that the wrong name but it's what I remember). The last one was with Motorhead making the comment that his ran away too.
In PCPshak's case (sorry for the name again), his was extremely dangerous as it extruded his shroud and locked his LDC on to it.

Now these guys are not knuckle heads and know how to tune.

So yes, I am concerned that if I buy a valve and don't know enough about it that I will either damage or hurt myself or someone else. Just wanted to fully understand what I would be getting into if I bought a SS valve.

I can see that your getting aggravated so, I will show myself to the door and avoid conflict. I thought I could use some of your information and ask questions since there is nothing out there in regards to what happens if you do this or that with the valve and your information has been more than anything since and before the valve has been launched.

Thats why I updated the thimble and poppet Its now impossible for that to happen Tim but you didnt mention that did you and I posted that and Im sure you read it! Your Help as you call it is nothing more than your attempt to discredit my valve. What ever Tim and Ill go back to playing with my SS valve you can go back to working on my valve design you took credit for(that I abandoned) I feel no need or want to cock 20+ pound springs anymore thats as dead to me as riding a Big Wheel over driving my car. You were not fulling me with your spring chart and Help as you call it. Your very transparent I knew your motives from your first post. You know what else is dangerous Tim Hanging a 24lb spring on the very fragile marauder sear and selling it to the public.

[triggertreat]

I do see Tim trying to question the new SS valve with a negative undertone over a number of post.  I know Tim is even toying with his own valve at a price that will undercut the SS valves price and hints at this in his valve thread.  I am not naive and can read between the lines.


I like all parties involved and like to stay neutral until I see this kind of thing going on.  I have all confidence in the SS valve and would say different if the need arises.  I have never had a dump situation with mine and feel like if there were a problem with the SS
 valve, I would've seen one by now myself.  Travis has admitted to some issues with the SS valve and has stated clearly that he is aware of them and is working overtime to correct them and make things right with all of his customers.  I can't think of anything else one could ask for.


I am currently running my Cobra valve because I messed with the SS valve and now can't get it to seal completely.   The cocking is ridiculously hard on the Cobra using Tim's dual dimensional spring.  I can't wait to get my SS valve fixed and get back to easy stock like cocking with the SS valve.


I hope Tim actually does try to develop his valve and then he will get a good taste of what it really takes to do that and be successful with the ever present naysayers who have no clue themselves making comments.


I hope Tim takes my strong comments towards him as useful, but if not I'll have learned more about him.


If Tim wants to compete with his own valve I am all for it, but let's be respectful of others efforts to enhance our hobby in doing so.

[rsterne]

Today I assembled the regulated tank block I got from Travis back in the summer.... It went well, and after a short learning curve installing shims, I was able to adjust it from 1000 psi up to over 2000.... I didn't try and go higher, but I am sure it will.... It has a 3K burst disc on the output side, and I didn't want to push it.... The adjustment is quite sensitive, you don't have to turn the 10-32 adjusting setscrew very far to move the output by 100 psi.... maybe 1 flat on the allen key or less....

Since the Cothran valve cannot be adjusted using hammer preload (or SSG gap), and needs to have the pressure adjusted to change the velocity, or retune for a different pellet weight.... it was a perfect match for an externally adjustable regulator.... Since there are two excellent pellets made by JSB that are quite different in weight (25.4 gr. and 34.1 gr.) I decided that to install the .25 cal upper on the lower that used the Cothran valve and the adjustable regulated tank block and I installed a 500 cc, 3000 psi bottle on it.... My initial adjustment of 2000 psi drove the 34.1 gr. JSB King Heavies at over 980 fps, but I used the opportunity to find out where the cliff was, and where the SSG gap needed to be adjusted to be close to the cliff, but solidly on the plateau, where the valve is operating stably.... That was with 2 turns of gap.... Then I shot the tank down to about 1700 psi so that I could drop the setpoint adjustment....

When increasing the setpoint pressure, you back out the 10-32 screw, which lowers the HP seat, moving it away from the piston and Belleville stack.... The seat opens, allowing more air to flow to the output side, raising the pressure and pushing the piston towards the (now lower) seat, against the Bellevilles, compressing them until the seat closes at the now higher pressure.... This puts no additional load on the seat, and can be done at any time.... When you want to decrease the output pressure, however, you need to drop the tank pressure below not only your current setpoint, but also below where you want the new setpoint to be.... The reduced pressure on the piston allows it to move away from the seat, and this allows you to turn the 10-32 screw in without putting additional pressure on the seat and possibly damaging it.... I wanted to start at 1800 psi and work my way back up, so I drained the tank down to 1700 and turned the 10-32 adjuster in until I felt slight additional resistance when the seat contacted the piston.... If you do this carefully and slowly, you can feel when they make contact.... When I added more air to the bottle, the gauge on the output side of the tank block moved up slightly, to about 1800 psi.... I shot a few shots, and the velocity was down to about 920 fps, so I simply backed the 10-32 adjusting screw out a fraction at a time, shooting a couple of shots at each setting, until I got my target velocity of 950 fps.... I then shot a couple of shots at each SSG gap setting, and recorded the results, which are on the graph below in red....



You can see the typical "cliff" exhibited by the Cothran valve which starts just before 3 turns out.... The velocity at 3 turns out is very unstable, with an ES of nearly 200 fps, because the valve is about to fall over the cliff.... However, at 2 turns of gap, it is rock solid, with about a 1% ES.... From previous experience I know that is the optimum place to run a Cothran valve, with the lowest hammer strike that allows stable operation and low ES.... I tried the 25.4 gr. pellets, and the velocity was over 1050 fps, so to get them to work I knew I had to lower the setpoint pressure.... I started simply shooting the 25.4 gr. pellets and watched the velocity fall as the pressure dropped.... I was pretty shocked to discover that to get down to 950 fps I had to drop the pressure in the tank all the way down to 1400 psi.... I shot a few more shots, to drop the tank pressure to 1300, and then turned in the 10-32 adjusting screw until I could feel it contact the seat.... I added air to the tank, the output gauge barely budged, and the velocity settled in at about 910 fps at about 1300 psi.... I slowly backed out the pressure adjusting screw, shooting a couple of shot at each adjustment, and stopped when the velocity with the 25.4 gr pellet reached my target of 950 fps.... The gauge indicated 1400 psi.... and I confirmed that by shooting the tank down until the velocity just started to drop, while the tank was still connected to the accurate gauge on my Great White.... Yes, I was getting 51 FPE at only 1400 psi.... I ran through the gap adjustments, and recorded the other curve (in blue) on the graph above.... The optimum gap was at 3 turns out, and the cliff started at 4 turns out, 1 turn more than at 1900 psi.... As expected, the valve requires a bit less hammer strike at 1400 psi than at 1900.... I also shot a few of the 34.1 gr Heavy pellets at that same setting, and that velocity is shown on the graph above as the black dot (872 fps).... So, with the 34.1 gr. pellets, I was getting 57.6 FPE at only 1400 psi.... pretty remarkable, and no adjustment made from the 950 fps setting with the 25.4 gr Kings....

Now that I knew that 3 turns out was the optimum setting for the 25.4 gr. Kings at 1400 psi, I recorded the pressure in the 500 cc bottle (using the gauge on my Great White), and shot 8 shots, on regulator, at 1400 psi.... I averaged the velocity (952 fps = 51.1 FPE), and recorded the pressure drop, which was 200 psi.... That works out to 0.97 FPE/CI, which is pretty low, but we are in new territory here, getting 51 FPE at only 1400 psi.... I repeated the test using the 34.1 gr. Heavies, and as I expected, the pressure drop was exactly the same, at 200 psi.... Since the energy per shot increased to 57.6 FPE, however, the efficiency increased to 1.10 FPE/CI.... I then backed out the 10-32 pressure adjuster to increase the setpoint back to 1900, set the SSG gap at 2 turns, and shot another 8-shot magazine at that setting with the 34.1 gr. Heavies.... The pressure drop was just over 200 psi, so I recorded it as 210 psi, and with the average velocity of 950 fps (68.4 FPE), that works out to an efficiency of 1.24 FPE/CI.... pretty decent at that power level....

The pressure drop per shot for all these tunes runs just about 25-26 psi per shot from the 500 cc bottle.... If we use a fill pressure of 3000 psi, with the 1900 psi setpoint, that should give 42 shots at over 68 FPE with the 34.1 gr Heavies.... and with the 1400 psi setpoint, that should give 64 shots at 51 FPE with the 25.4 gr. Kings and nearly 58 FPE with the Heavies.... I think those are quite acceptable numbers, and tuning back and forth between the 25.4 gr. and 34.1 gr. pellets (both at 950 fps) requires only resetting the external regulator adjustment, and one turn on the SSG gap.... In fact, if you don't care about getting the full 64 shots at the 1400 psi setting, you don't even have to change the SSG gap, you can leave it at 2 turns, and just lose a few shots.... If you have the gun tuned at 1400 psi, you can shoot the Kings at 950 fps and the Heavies at 870 fps, for the same number of shots, with NO adjustment necessary....

Bob

[YEMX]

Most impressive Bob!!

[oldpro]

 I neet to get you some smaller jets to finish up the testing

[rsterne]

Today I worked on a new SSG to go inside the AR style stock adapter I made a while back.... I had to shorten up the adjusting bolt and spring guide so that it wouldn't interfere with the stub on the stock, as this is a paintball stock and uses a plastic slider.... This version uses a PRod trigger with a taller sear from Lloyd at AirGunLab to work with the thicker MRod tube.... The forestock is a simple piece of ABS plastic pipe slide over the main tube and secured with setscrews.... Here is what the finished gun looks like....



The 500 cc tank is heavy, so the all up weight is 9.5 lbs including the scope and rings, so the bare gun is about 8 lbs.... If you hold it with your hand just behind the tank block, it balances right there.... It uses the Cothan valve and the Cobra tank block with externally adjustable regulator.... It is currently tuned to shoot the 34.1 gr. JSB King Heavy MkIIs at about 950 fps (68 FPE), for about 40 shots per fill.... With the Cothran valve, the easiest way to adjust the velocity is with the regulator.... the pressure adjustment (currently 1900 psi) is a 10-32 setscrew on the bottom of the tank block.... The barrel is a LW Polygonal, 23.8" long, and fitted with a Hatsan Air Stripper.... The MROd receiver was bored out about 1.5" to accept the larger diameter barrel.... so the free floated barrel is very rigidly mounted to the receiver.... The bolt was fitted with a 3/32" diameter probe, making the chamber area the same as the barrel and transfer porting, which is 0.234"....

All in all, I am very pleased with the way this turned out.... It is easy to cock, with the SSG having 3 lbs. of preload on an 8 lb/in spring.... The 51 gram MDS (steel cored) hammer has 0.79" of stroke, and the SSG gap at this tune is 2 turns, so the cocking distance against the spring is 0.67", making the maximum cocking force less than 8.5 lbs.... About the only thing that would be a nice addition is a BiPod mount on the bottom of the tank block.... My thanks to Travis and Lloyd for their help in procuring the parts for this build, without them it would not have been possible....

Bob