GTA
All Springer/NP/PCP Air Gun Discussion General => "Bob and Lloyds Workshop" => Topic started by: lloyd-ss on October 29, 2012, 01:34:41 AM
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I've attempted making a few regulators in the past, applying less than 100% effort and achieving results that reflected such.
This time I had a goal in mind and did the requisite design work, and the results are pretty fair. Input is variable up to 4,000psi. Output is field adjustable with An allen wrench from zero to 3,500. I am testing it in the pic with 3,750 input from the CF tank, regulated down to 2,950psi. I am using the gauge and bleed from the second tank, but the valve is closed to isolate the regulator. So far, I have seen no creep. There are about 3 turns per 1,000psi, so the adjustability is fairly accurate. That is why it is so long.
I could be wrong, but I don't think you can buy a reg with this adjustability for less than an arm and a leg.
I'll get some pics of the internals. They are nothing special, just accurate.
If you can buy something like this, let me know. It was a lot of work, LOL.
Lloyd-ss
(http://i226.photobucket.com/albums/dd79/loyd500/Grumpys%20Mrod/First-regulator-a.jpg)
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Now THAT is a project I could use.... photos of the guts will be great!....
Bob
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Now THAT is a project I could use.... photos of the guts will be great!....
Bob
+1 on the pics, that is a cool project 8)
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looks like a great idea lloyd-ss. ;D regulators that accept 4k to 6k input with that much adjustability run $300 + ;D
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great project hope it work well
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Congrats!!!!
Totally awsome project Lloyd. Would love to have a fraction of your skills and knowledge. I can certainly send you a few airguns to test this with.
:)
As long as I get a regulator for each.
Keep up the most excellent work sir!!!!
SAFE & Happy Shooting!!!!
Dave
8)
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Is it painful being so smart? Way too much information to fit in my head.
Richard
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Yeah for a barebones new regulator, you are normally looking at around $300 + gauges and such.
That's awesome lloyd. Let me know when you start shipping them :D
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You guys are funny. No plans on selling anything like this. It's going into a one-off project I've got going.
Actually, it isn't my idea, I got the basic ideas from this page
http://www.zdspb.com/tech/misc/maxflo.html (http://www.zdspb.com/tech/misc/maxflo.html)
The one I built is a combination of the AKA Sidewinder with the pressure adjusting screw in the end, and the Ion Vertical reg, but with Belville washers instead of a coil spring. The Belville washers are needed to handle the spring loading that high output pressures produce in a reg.
Pictures are in the works.
Lloyd-ss
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If I understand those two diagrams correctly.... It looks like you move the high pressure seat up and down to change the regulation point?.... What are you using for a Belleville stack to achieve the wide adjustment range?.... What size washers, and what piston diameters?.... I'm wondering if I can start with a piston from a Ninja and make a housing to make it adjustable.... I've already made one regulator using that piston, and they are easy to obtain....
Bob
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Here are the pics.
7/8 OD x .065 wall tube 4.72 long.
side input. output on the right. set point adjustment screw is in the left end.
(http://i226.photobucket.com/albums/dd79/loyd500/Grumpys%20Mrod/reg-1a.jpg)
Partially disassembled. Initial assy just barely compresses the Belville stack.
With springs barely compressed (just enought to keep them from rattling, that is minimum pressure.
(http://i226.photobucket.com/albums/dd79/loyd500/Grumpys%20Mrod/reg-2a.jpg)
All apart now. The air enters thru the fitting into the side of the body, captured between the 2 orings on the adjustment screw.
Into the small hole into the adjustment screw, then thru an axial hole out the right hand end of the adjustment screw.
The spring stack is 11 pairs of a .730 OD x .390 ID. one is .028 thk(171 lbs when flat) & one is .034 (326 lbs when flat).
So a load of approx 500 lbs will flatten the stack. Doesn't matter if it has one pair of springs or 11 sets of springs.
The eleven sets give a total travel .231" which is how you get a 3500 psi adjustment range.
Piston bore diameter is .430 (.145 sq in) so the springs will go flat at about 3500psi.
(http://i226.photobucket.com/albums/dd79/loyd500/Grumpys%20Mrod/reg-3a.jpg)
Screwing the adjustment screw OUT raises the pressure. air travels out the tip of the adjustment screw, up a short distance
along the side of the small end of the piston, then in thru the side hole in the piston, and then up thru the center of the piston.
In the piston chamber, it presses down on the piston, flattening the springs until the small delrin tip on the end of the piston seals up the air input hole.
(http://i226.photobucket.com/albums/dd79/loyd500/Grumpys%20Mrod/reg-4a.jpg)
Here you can see the plastic seal plug that stops the input of HP air. But in this pic you can't see how the sir travels up thru the piston.
You can see the side hole in the 2nd and 3rd picture above. An important thing to note about this type of reg is that
it is not self venting. Therefore, you can start with the air pressure set low, and screw the adjuster OUT to increase
the pressure. But to LOWER the pressure after the tank is filled, you can't just screw the adjuster in because the HPA can't vent.
You have to bleed the air from the tank, and then screw the adjuster in.
In the part on the right you can see the .430 dia piston chamber.
(http://i226.photobucket.com/albums/dd79/loyd500/Grumpys%20Mrod/reg-5a.jpg)
That's the basics
Edit- 10-30-12- by Lloyd-ss- Studying this some more, I think it can be simplified by swapping the plastic sealing element and the tiny axial hole between the adjuster and the piston, lengthening the nose on the piston, and shifting the input hole toward the right. That way, no air would actually have to flow through the adjuster. It would eliminate one potential leakage point. The functionality would be identical.
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Excellent writeup, all the details are there, for sure.... I never really gave much thought to the total travel required for that adjustment range, and hence the need for a long Belleville stack.... It would mean the Ninja piston would likely be too short....
RE your EDIT.... It took me a while but I think I understand now.... You would eliminate the upper O-ring in the photo from the adjuster, right?.... The air would come up along the side of the adjuster, across the Delrin seat, and then into the axial hole in the end of the piston.... Why would that hole have to be off center?.... You would no longer need a side hole in the piston, the air would pass straight through the middle, through the hole in the seat.... Or am I missing something?....
Is there an easy way to balance the pressure on the adjuster so that it can be adjusted under pressure?....
Bob
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Is there an easy way to balance the pressure on the adjuster so that it can be adjusted under pressure?....
Bob
Bob,
This part first.
Turning the pressure up is easy, just back the adjuster out.
Reducing the pressure is not as easy. If the application of this reg is in a typical situation, then there will be a tank on the output side of the reg. If for example, it is already at 2500psi and you want to set it to 2000, then you will somehow have to reduce the pressure in the tank for that to happen. Because the piston is in a state of equilibrium between the spring stack and the output air pressure on the piston, the adjuster, if you are trying to reduce the pressure, will in the example above, be trying to move the piston to compensate for 500 psi, or 72 pounds (.145 sqin on the piston). My guess is that the adjuster would badly gouge the plastic seat if it were trying to apply 72 pounds of force to the plastic end on the piston. Adjusting it a few psi would work ok, but not 500 psi.
There are industrial regulators with built in unloaders, but you would essentially be trying to drain the gun's reservoir. My plan for that situation was to have an inline valve on the input to the reg that would be turned off, then either bleed or shoot the gun down to the desired pressure, and then turn the adjuster in and open the air up again. As I said though, you could probably adjust the pressure 50 pounds or so without bleeding. If you have a big tank with a high shot count, shooting the gun down could be slow. A bleeder would be necessary.
Lloyd-ss
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Beautifully done!
Tom
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Excellent writeup, all the details are there, for sure.... I never really gave much thought to the total travel required for that adjustment range, and hence the need for a long Belleville stack.... It would mean the Ninja piston would likely be too short....
RE your EDIT.... It took me a while but I think I understand now.... You would eliminate the upper O-ring in the photo from the adjuster, right?.... The air would come up along the side of the adjuster, across the Delrin seat, and then into the axial hole in the end of the piston.... Why would that hole have to be off center?.... You would no longer need a side hole in the piston, the air would pass straight through the middle, through the hole in the seat.... Or am I missing something?....
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Thanks Bob,
Look at this one, it is what I think will be the easiest to make, and I like that.
http://www.zdspb.com/media/tech/regs_akalmplpr.JPG (http://www.zdspb.com/media/tech/regs_akalmplpr.JPG)
All these PB regs are made to work with 800psi input ( The usual paint ball tank already has an 800 psi reg mounted, so most of these regs are designed to take 800psi down to half that or less. And the output is always set to achieve 299 fps with a 66 gn (?) paintball, so they need very little adjustability. We need a lot more, plus a very high operating pressure. You could possibly preload the spring by screwing the two main endplugs in so that the miinimum pressure was always 1000 or so psi. I don't see why that wouldn't work.
This reg is more ascience project than anything else, LOL
Lloyd
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That diagram is functionally exactly what I was describing.... There are no holes in the adjuster, only a seat.... The HP air enters beside it (with yours I just envisaged removing the upper O-ring).... The hole in the piston is straight through, no hole in the side.... Easy to make.... I like it....
I understand the problem about screwing in the adjuster to reduce the pressure when the piston is loaded.... It would likely destroy the Delrin seat.... Never thought of that.... A bleed fitting in the hose to the gun (or built into the LP side of the regulator) would seem to be the way to lose the least air.... You need to be able to bleed it to remove the hose anyway, and the Foster QD on the gun has a check valve in it to prevent backfilling the hose....
Bob
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Lloyd,
You do some great work sir! Truly inspirational.
BTW, That is a very LARGE coffee cup you have that carbon fiber tank sitting in! I thought I went through coffee quick.
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Rescue, ha, ha, you a funny guy, too! It is a good thing i have small deck facing the woods right out the back door of my shop. Saves a lot of trips to the house. LOL
lloyd-ss
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Lloyd.... I'm missing something on how this regulator design works in terms of the maximum pressure required to flatten the stack.... You say that the piston bore is 0.43" (0.145 sq.in.) so that takes 3500 psi to flatten the stack (508 lbs).... Don't you have to subtract the area of the lower end of the piston?.... The lower chamber is at the same pressure as the upper (once the regulator closes).... Let's say it is 1/2 the diameter of the large end.... It's area would be 1/4 (of 0.145 sq.in.) = 0.036 sq.in. so the total effective area would be 0.109 sq.in.... That would require 4600 psi to flatten the stack....
Expanding on that thought.... If you move the HPA inlet to the smaller chamber, it will now be running at, say, 5000 psi.... The chambers are no longer at the same pressure (once the regulator closes) because the valve is on the end of the piston.... The force OPENING the regulator would now be increased by 4500 x 0.036 = 180 lbs.... making the force to flatten the stack (and overcome the HPA) 680 lbs.... With the 0.145 sq.in. larger piston opposing that, it would take 4700 psi to flatten the stack....
Please review the above and let me know if I'm losing my mind....
Bob
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Bob,
I think you have it partially right. First, with the design I have, it will indeed take about 4600 psi to flatten the stack. Good catch. The consequences of that are that some of the axial travel is lost... approx 1/4 of it. Because the adjustment can be screwed in and out quite a bit, that is not a problem, but a diameter for the upper part of about .48 would have been better.
For the other style of regulator that you are talking about, the scheme you are mentioning will not work, for exactly the reason you are citing. The moving part of the reg that makes the seal has to be a straight tube, thin walled and small dia, with no steps on the high pressure side. Steps will cause the regulation to vary significantly with changes in the tank pressure.
The style that I made, although not fully balanced, is only susceptible to imbalances in relation to the area of the tiny inlet hole that supplies the HPA. For the other style, that imbalance is in relation to the frontal area of the moving seal tube.
I hope that makes a little sense.
Lloyd
edit: I checked my left over springs and it looks like I can replace all the .034 thick ones with .028 ones, which will will pretty much restore the full travel to the regulator. Thanks for that catch, Bob. I haven't done all the calcs yet, but I will when I take it apart.
Lloyd
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No problem.... Now, while we're on regulators, I have a BASIC question that has been bugging me.... I've seen lots of regulators with stacks something like this....
)()(())(())(||
or whatever, but a mix of singles and doubles, all the same thickness (except the flat shims).... I find this totally confusing, for the following reason.... Let's say it take 100 lbs. to flatten a single 0.020" thick disc.... Let's further assume that the stack is subjected to a load of 100 lbs.... Wouldn't the single discs flatten completely, so the stack now looks like this?....
|||(())(())|||
In the original stack, the travel would be 8 times the "cup" of one disc.... If the cup was 0.020", the travel would be 0.160".... The "spring rate" (according to my math) would be K/6, where K is the rate of a single disc....
Once a load of 100 lbs. is applied, and 4 of the discs have collapsed (and the other 4 are collapsed half way), there is only 0.040" travel remaining.... The spring rate for that remaining portion of the travel would be much stiffer than it was initially.... My math says it would be K/2.... ie 3 times as stiff as it started out.... The stack started out 0.400" long with no load, and at 100 lbs. it was 0.280" long....
If the stack had been arranged like this.... (same number of bellevilles = 12)....
))(())(())((||
it would have a rate of K/3 and a travel of 0.120", but the spring rate would be a constant instead of losing half the travel and having a sudden change in rate.... At the same 100 lb. load, it would have compressed 0.060", and still have that much travel remaining.... This stack started out 0.360" long, and at 100 lbs. it is 0.300" long.... It has a linear spring rate, more travel when half loaded, and the only difference is that it may take a slightly different shim pack to set the pressure you want....
My questions are.... Firstly, do I understand this properly.... In a mixed stack of singles and doubles, do the singles go flat first?.... Secondly, if that is true, WHY would somebody assemble a regulator with a mixed stack of singles and doubles?.... I've found that once bellevilles are driven completely flat, they tend not to rebound conpletely but take a "set".... Why would somebody complicate their life by mixing the stacks?....
Bob
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You think too much !!
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Bob,
You have the stacking figured out correctly. The top example will give a stepped rate. Soft then stiffer. I have to go to work now. But there is LOT to your question. I'll be back!
Lloyd
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The reason for single washers to be mounted is to have some extra movement/opening when pressure is low on the secondary side.
And I also made my own regulator for +300bar to 120-250bar. These are my "workdrawings".
I only made this one for when refilling my HW100, but the parts are made rather small so they can be retrofitted to an unregulated airguntank.
The belleville washers can be otherwise stacked or exchanged for other pressures.
https://www.dropbox.com/s/kluxmlitdv5fevh/2012-11-07%2002.09.51%20%28Medium%29.jpg (https://www.dropbox.com/s/kluxmlitdv5fevh/2012-11-07%2002.09.51%20%28Medium%29.jpg)
The overall lenght of the regulator is only 58mm.
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Regarding the Belleville stack orientation, Think progressive!
Regulators are not supposed to be on off switches. Small changes need sensitive responses ;-)
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For those that think a regulator can respond during the 1-2 mSec it takes for a shot to occur, I would like to see some proof.... I have used regulators with a gauge on the output side, and you can see the needle drop during the shot and take up to a second to reach full pressure again.... I simply don't believe it happens....
Regarding the idea of having a progressive spring rate, I can see that as being an advantage in some applications, but not in a regulator.... The FORCE isn't constant anyway, even with a constant spring rate the disc springs develop a lot less force when the regulator is open (ie the output pressure is low) than when it is on the seat.... Add in the fact that once you drive the bellevilles to flat you damage them, and I fail to see the point in using a mixed stack....
If I've got it wrong, please enlighten me....
Bob
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For those that think a regulator can respond during the 1-2 mSec it takes for a shot to occur, I would like to see some proof.... I have used regulators with a gauge on the output side, and you can see the needle drop during the shot and take up to a second to reach full pressure again.... I simply don't believe it happens....
Regarding the idea of having a progressive spring rate, I can see that as being an advantage in some applications, but not in a regulator.... The FORCE isn't constant anyway, even with a constant spring rate the disc springs develop a lot less force when the regulator is open (ie the output pressure is low) than when it is on the seat.... Add in the fact that once you drive the bellevilles to flat you damage them, and I fail to see the point in using a mixed stack....
If I've got it wrong, please enlighten me....
Bob
You should have around twice the volume of port and barrel as the regulated volume. Larger regulated volume means you can go down in pressure >> more shots >> higher "effiency" of the airtank.
A larger volume also secures that after shot taken, there is enough pressure in the regulated area to shut of the valve quick and consequent >> not "spilling" air.
Sorry if some terms aren't correct english.. :o
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You should have around twice the volume of port and barrel as the regulated volume
Sorry, I don't understand how it relates to the barrel volume.... I always strive for about 1 cc of volume between the regulator and the valve seat (outlet) for every FPE the rifle is expected to produce.... Less than that and you have to run more pressure, hence fewer shots.... I agree that having lots of volume mya help the valve close quicker and/or avoid bounce as well....
Bob
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I believe he is referring to the "chamber" area of the barrel. Behind the pellet and in front of the bolt face. That was my take.
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Bent,
Making regulators is not easy. Did yours work out ok? I am curious about the groove/gland configuration for the o-rings on the moving parts. It seems the grooves work better when they are narrower and deeper, compared to a groove for a static o-ring. What did you find that worked best? Are you using the tiny 1mm cross section o-rings on the moving parts?
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For those that think a regulator can respond during the 1-2 mSec it takes for a shot to occur, I would like to see some proof.... I have used regulators with a gauge on the output side, and you can see the needle drop during the shot and take up to a second to reach full pressure again.... I simply don't believe it happens....
Regarding the idea of having a progressive spring rate, I can see that as being an advantage in some applications, but not in a regulator.... The FORCE isn't constant anyway, even with a constant spring rate the disc springs develop a lot less force when the regulator is open (ie the output pressure is low) than when it is on the seat.... Add in the fact that once you drive the bellevilles to flat you damage them, and I fail to see the point in using a mixed stack....
If I've got it wrong, please enlighten me....
Bob
If one did not want the regulator to screech, buzz and whine, he might not care about spring rate tuning.
True also, that some conditions might allow straight rate without these undesired side effects.
Regarding response during a firing cycle, Such rapid response, if attempted, will surely be the death of most regulation valving seals, certainly resulting in deformation that results in undesired outlet pressure change. (creep)
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Bent,
Making regulators is not easy. Did yours work out ok? I am curious about the groove/gland configuration for the o-rings on the moving parts. It seems the grooves work better when they are narrower and deeper, compared to a groove for a static o-ring. What did you find that worked best? Are you using the tiny 1mm cross section o-rings on the moving parts?
It works, but still need fine tuning. First i used POM/DELRIN for the valveseat but half the time it didn't close before the pressure was about 25 bars higher than setpoint. After changing to PTFE, which are a litttle softer it's maybe one of ten where it goes 15-20 bars to high. Haven't had time since I made it, but I think I polished/rounded the valvepibe to much... I made it just 3 weeks ago, and Christmas and familytime is rated higher right now... ;)
The O-rings are 11,28x1.18(the same as I use for the portpart on my HW100), so it's a tight fit, and the little hanging could also come from this. Even if everything got a little molykote, wiped dry afterwards.
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Bent,
I think we are similar in our development. Mine is working ok, but can be better. Thanks for the idea about the valve seat material. I will try some different ones. Also, I forgot to put a vent hole in the side of mine, ha, ha. I will fix that too.
Have you seen this site?
http://www.zdspb.com/tech/misc/maxflo.html (http://www.zdspb.com/tech/misc/maxflo.html)
LOTS of drawings of regulators. Also, look at their paint ball gun animations. They are complex and beautiful! (techno-geek) ;D
Lloyd-ss
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Llloyd,
Sounds like we are.. ;) Learning by failing.... 8) And I'm still failing a lot.
I'm rather new to PCP's first time I shot a PCP was in March this year.
I'm used to working with spreadsheets and development, and in PCP I can combine hobby, shooting, developing and some calculation all in one.... ;D ;D
The reason for the narrow groves was to avoid the O-ring from "rolling" in case it sticks a little to the wall.
Never seen that page before, great description and graphics.
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Lloyd, I notice you have the thinner Bellevilles in the middle of each set.... I did mine the other way and it took a long time (like ~30+ seconds) to reach the setpoint.... ie it crept up the last 100-200 psi.... Do you know if it should make a difference?.... I'm using 0.032" and 0.022", with flat loads of 260 lb. and 105 lb. for a total of 365 lbs.... Are you using any lube on the washers, and/or did you polish the rims?....
Well, I just swapped them around.... They used to be Thin Thick Thick Thin for each (()) double-paired set.... Now they are Thick Thin Thin Thick.... and the problem went away.... Interestingly, the setpoint didn't change, just the response time to balance.... I have a total of 14 Bellevilles and the adjustment range I have is 1200-2700 psi, but it takes only about one flat on the adjusting bolt (1/6th turn) for a ~100 psi change.... Anyway, works fine for my purposes....
Bob
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Bob,
That is interesting about putting the thicker Bellvilles on the outside of the quads gave a faster response time. I remember reasoniing through which should be on the outside, but honestly, I can't explain the logic. The idea of using some lube in the stack is interesting. Maybe an extreme pressure lube, like lathe center point lube, or hypoid gear oil? I think I might try some lube in the stack.
Lloyd
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I would think it might be worthwhile polishing the edges of the bellevilles with 600 grit and I'd like to try moly paste burnished in.... Anyway, I was using it today and swapping them around was a HUGE improvement in the balance time....
Bob
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Bob,
Thinking about it, that certainly makes sense. Regulators that have coil springs don't have the friction of all the Bellville's sliding past each other, but you need the Bellville's to get the required pressure and travel. The coil springs are basically frictionless in a reg. And then when the spring stack is almost at equilibrium, any little bit of friction becomes a big player in the final settling of the reg. It is making more sense all the time.
Lloyd
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I guess that would speak in favour of using single, heavy Bellevilles (eg. the 0.047" with a 600 lb. flat load) instead of pairs of thinner ones.... when high forces are required.... The only downside is they have less travel....
Bob
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Makes perfect sense reducing friction at the contact areas of each and every washer so there movement ever so minor is done so with the least amount of parasitic drag/friction.
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I took the reg apart and and lightly sanded them with some 1000 grit I had handy. I was doing this on some white paper and noticed that there were some very tiny metal flecks imbedded in the surface of some of the Bellville washers. The flecks all came off. The washed with 409, hot water, dried on white paper. Checked under a lighted magnifier. Sanded the bore of the tube a little, too, until it felt nice and smooth. Then, using some nitrile gloves I have for nasty stuff, smeared the tiniest amount of moly on all the surfaces and reassembled.
The recovery speed is a little faster, but I think the return to the set point is more consistent.
Thanks for that tip.
Lloyd-ss
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I did the same thing with 800 grit and found no difference.... I only sanded the top and bottom edges....
Bob
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How does the Ninja deal with the stiction issue Don't they use an AL housing?
Tom
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The belleville washers dont touch the housing (AFAIK), they only touch the piston and each other.... If the washers are in a single stack, only the edges of the washers touch.... If they are doubled up, then each pair of washers have one entire surface in contact.... I think that slows the response time as I've never really seen the problem before doing that....
Bob
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It works, but still need fine tuning. First i used POM/DELRIN for the valveseat but half the time it didn't close before the pressure was about 25 bars higher than setpoint. After changing to PTFE, which are a litttle softer it's maybe one of ten where it goes 15-20 bars to high. Haven't had time since I made it, but I think I polished/rounded the valvepibe to much... I made it just 3 weeks ago, and Christmas and familytime is rated higher right now... ;)
The O-rings are 11,28x1.18(the same as I use for the portpart on my HW100), so it's a tight fit, and the little hanging could also come from this. Even if everything got a little molykote, wiped dry afterwards.
Bent... I have DIY regulator project for my gun. it's 27 mm inner diameter titanium cylinder. So far seems it's work, I mean i can set the regulated pressure on firing chamber from 800 psi to 2000 psi by turning the screw in front the body. The problem is when i pull the the trigger ( i set for 2000 psi) regulated pressure goes to 1800 psi, it should be directly back to 2000 psi but my reg need 20 second to reach 2000 psi again. I have tried to adjust the inlet air on piston from 1,5 mm to 4 mm, it doesn't work..still 20 second to reach set-point pressure. Do you think this because hard plastic seatvalve..? Any suggestion..?
I dont know how to attach the pic of my reg..
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That is basically what I was finding as well.... a quick surge to nearly setpoint, and then several seconds to get to the ultimate pressure.... It seems worse with paired (doubled) washers than what you get with single (heavier) bellevilles.... I think the friction between the entire face of the paired washers is an issue....
Bob
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That is basically what I was finding as well.... a quick surge to nearly setpoint, and then several seconds to get to the ultimate pressure.... It seems worse with paired (doubled) washers than what you get with single (heavier) bellevilles.... I think the friction between the entire face of the paired washers is an issue....
Bob
I have used 2 different type of spring (disc spring & coil spring). Both have same symptom, several second to reach ultimate pressure.
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Just thinking about this in a different way.... If the spring rate is very high, then the piston only moves a tiny amount after a shot for a given pressure drop.... That means that the seat is barely uncovered and the flow rate is very low.... so the recovery time is long.... You need a given force to balance the reg at whatever the setpoint pressure is.... but that can be achieved by a high spring rate and a small travel, or by a lower spring rate and a longer travel.... If the rate is lower, the regulator will open further for a given pressure drop, and the flow rate should be higher.... and the recovery faster.... Just a thought....
Bob
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Consistency of recovery pressure obtained and the sensitivity to adjustments can make heavy preloaded arrangements with little travel more problematic. It seems the makers don't double up the washers but go thicker when possible.
All the tanks I test seem to slightly overcharge the after reg chamber when filled so the first few shots can't be trusted. The bigger the chamber the more shots it takes. 5 is plenty to get the Ninja Tank Output stabilized on my rigs.
For those that want to avoid the inevitable Price increase it would be wise to get your tanks and Regs soon as a price increase is gauranteed in the next few weeks. Ninja is considering the purchase of 22 ci tanks from cliff div if the Airgunners support that move with adequate demand. The numbers have to be large to make it happen. Catalina sells vessels but it would be great if Ninja had them in stock with regs.
Only on the GTA.
TimmyMac1
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It seems that we are all seeing the same pattern of operation with these high pressure regulators. I agree that most of the lag time issue is due to the miniscule flow as the set point is approached.
But I still believe that the change in the o-ring dynamics during a refill situation, or change of set-point causes the inconsistency in the first few shots. O-rings often misbehave in reciprocating/reversal applications where fine control is required. Changes in gland depth (deeper) and width (narrower) and material (harder) are usually needed to control the shifting/extrusion of the o-ring in the gland that can be greater than the tolerance of the desired output pressure change in the regulator. A diaphragm style that eliminates the o-ring movement would behave better, but getting adequate movement in a diaphragm usually means a larger diameter, and more bulk, plus high cost at the pressures we are dealing with.
Back to my original regulator, I have milled a 1/8 slot lengthwise to expose the edges of the Belville washers, and it is quite interesting to see their behavior in operation. It makes it painfully obvious that at the set point, with each shot, there is basically no "observable" movement of main piston as the low pressure reservoir refills after each shot. That last little bit of re-fill (and over-re-fill) has more do with the elasticity and creep of the inlet sealing seat and o-rings than any movement of the Belvilles.
Just my observations.
Lloyd-ss
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If there is "no observable movement", even with the very long stack of Bellevilles in your regulator, the it would appear that the hardest possible seat material for the HP inlet that will still seal would be better.... ANY extrusion of the seat into the (tiny) inlet port would drastically affect the flow....
I wonder about copper on steel?.... can we get pure copper BB's ?
Bob
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Good thought, Bob. Just for clarification, by no observable movement, I meant with the unaided eye.
Another thought. In normal operation, the piston reaches an equilibrium point and applies only enough pressure to the HPA inlet seat as is required to stop the flow of air. Depending on the seat material, that might be a few pounds, or several. And it will keep leaking, and therefor building up excess pressure, until the shutoff is 100%. That creep to 100% shutoff is what we are seeing on the pressure gauge and stop watch. The sealing interface must be perfect. (*** another thought-- you shoot the bottle down to 2000 psi and the seal at the inlet orifice is fine. Then you refill to 3000 psi. I t probably takes a little more force on the seat to to get it to seal at the new 3000 psi.***)
Looking at my design, I see a problem with the adjustable nature of it. When I make an adjustment, it actually twists the inlet orifice against the sealing seat, which could damage, or at least wear, the seat. When increasing the pressure set point, this is not too big of a deal because I am backing the pressure off the seat. But when DECREASING the pressure, unless I bleed the low pressure reservoir first, then tightening the adjustment screw inward will apply a LOT of force to the sealing seat. I am going to see how to make that inlet orifice non-rotating to eliminate that problem. There are a couple of other things I don't like about the whole inlet end of the reg that I ought to re-design. I had resisted, but it is the right thing to do.
Lloyd-ss
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My design has a rotating seat as well.... It's denting the Delrin face on the bottom of the piston, you can see a "bump" in the middle of the donut shaped depression where it is extruding into the hole in the center of the inlet port.... I think in my case a small copper disc replacing the Delrin might be the answer.... I always bleed the regulator no matter which way i'm adjusting it.... I'm afraid of it wearing/tearing the Delrin otherwise....
Bob
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Another thought. In normal operation, the piston reaches an equilibrium point and applies only enough pressure to the HPA inlet seat as is required to stop the flow of air. Depending on the seat material, that might be a few pounds, or several. And it will keep leaking, and therefor building up excess pressure, until the shutoff is 100%. That creep to 100% shutoff is what we are seeing on the pressure gauge and stop watch. The sealing interface must be perfect.
yes.. I agree the creep to 100% shutoff caused by the leak, the sealing interface not 100% perfect. It's not easy to make a perfect
shutoff valve, because we deal with 200 bar HPA, in another hand piston (seat valve) has no significant force when he hit feed orifice. Yes.. piston is pushed by air pressure in the firing chamber, but the force from disc spring against it.
This is my thought....to reach set point, let says 135 bar
a. Using hard spring means short piston travel to hit feed orifice.
b. Using softer spring means longer piston travel to hit feed orifice.
At point b, after seat valve hit feed orifice, it is easier/faster to have 100% shutoff because with same "creep" of air pressure, piston/seatvalve has more force to make perfect shutoff than point a. At point a, the force of "creep" will be used against the stronger spring force.
I will try to use softer spring, my reg now has 2 mm piston's travel to hit inlet orifice
I wish you guys.. know what i mean (sorry for my English)
Looking at my design, I see a problem with the adjustable nature of it. When I make an adjustment, it actually twists the inlet orifice against the sealing seat, which could damage, or at least wear, the seat. When increasing the pressure set point, this is not too big of a deal because I am backing the pressure off the seat. But when DECREASING the pressure, unless I bleed the low pressure reservoir first, then tightening the adjustment screw inward will apply a LOT of force to the sealing seat. I am going to see how to make that inlet orifice non-rotating to eliminate that problem.
Lloyd-ss
I choose to bleed my firing chamber rather than to fix the damage seatvalve
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Ichsan,
Yes, I understand what you are saying. Making regulators that repeat within 2 or 3% is difficult and I have much to learn, but there are so many different approaches.. Your comment about bleeding the air pressure before making adjustments is good, I think.
Here is a website that has lots of drawings of regulators. Very good reference.
http://www.zdspb.com/tech/misc/maxflo.html (http://www.zdspb.com/tech/misc/maxflo.html)