FX What causes regulator to be same pressure as the rest of the air tube?
- Thread starter jem91
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This "current breed" FX owner found the AMP regulator in his "current" FX Bobcat had been thread locked by FX. So disassembly required application of a lot of heat. Then when his "current" Boss had issues rather than struggle with the thread lock bought 3 huma regulator and eventually replaced the AMP in all 3 FX.
The Huma is more easily adjusted with the pressure clearly marked on the body. There has been zero noticable creep on any of the 3 Huma regulator.
The Huma is more easily adjusted with the pressure clearly marked on the body. There has been zero noticable creep on any of the 3 Huma regulator.
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Yes, and this is why I noted that on air tube type guns like your bobcat I favor the Huma regs. I have Huma regs in both my wildcat MK2’s and on my Benjamin marauder, but on my wildcat mk3 “bottle” gun, my crown, and both my mk2 impacts I stick with the fx amp reg.
Just an fyi, on my wildcat MK2’s and almost every Huma reg I’ve installed on other people’s air tube type guns, that bar indicator label was off. I use a Huma reg tester tool to verify correct bar settings instead. The person that taught me how to work on fx guns told me to just remove the paper labels that Huma puts on their air tube type regs because some of the times they are off.
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Back to the OP’s dilemma about reg pressures matching up to fill pressures, when pulling out an amp reg for a reseal(I’m going to assume the fault is due to o ring failure and not piston seal. With piston seal failure most of the time what you’ll get is reg creep in a bad way)
make sure to change out all the regs o rings- that’s the one outside the main reg body, one inside the reg body, the one on the base of the piston, the two on the adjustment screw, and lastly, the one inside the reg tunnel. I blame this particular one the most when reg pressure matches fill pressure based on my experiences. If air seeps past that seal it bypasses the insides of the reg so it’s basically like not having a reg installed anyway. This o ring tends to dry up crispy like, and gets glued into the o ring groove, making removal a good test of your patience.
make sure to change out all the regs o rings- that’s the one outside the main reg body, one inside the reg body, the one on the base of the piston, the two on the adjustment screw, and lastly, the one inside the reg tunnel. I blame this particular one the most when reg pressure matches fill pressure based on my experiences. If air seeps past that seal it bypasses the insides of the reg so it’s basically like not having a reg installed anyway. This o ring tends to dry up crispy like, and gets glued into the o ring groove, making removal a good test of your patience.
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Tube or bottle is irrelevant, thread locker is relevant.
The markings get you close. Zero markings on the AMP. You have to write down how many turns when you disassemble.
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Hi jem91. As I said in my previous post (post number 19), the problem is that the O-ring on the set screw nearest to the piston needs to be replaced. Here is a thread that has a picture in the 1st post. In the picture you will see a set screw O-ring that has a red asterisk next to it. THAT is EXACTLY the O-ring that is damaged and is allowing air from your tank to go directly into your plenum. You need to replace that O-ring, but you should replace both of the set screw O-rings while you're at it. I see no reason to replace any other regulator O-rings unless air is leaking (you'd know if it was leaking because your tank pressure would drop significantly overnight or over the course of several days). I see no reason to buy a new regulator -- O-rings just need to be replaced sometimes.
FX AMP Regulator - Dreamline Bottle
Newman's video (910 Airgun Tuning & Repairs) on the AMP reg is really great. But it's fast. I usually need to put things on paper to memorize them. So, here is what I've just put together. Let me know if you see something that does not make sense. PDF attached, so if you want to print it...
www.airgunnation.com stovepipe
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I was mainly worried if the high regulator pressure would cause any damage but seems to be a common thing with time and use, Its an earlier model so those seem to have a few extra issues in general and some parts were updated later.
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History (feel free to skip to problem)
O.K. I am pretty sure I will get the same answer but I seem to be having a similar problem. I do have a couple caveats though. I bought a used an airacuda max to see if I liked the sport enough and I did. I am a physicist so I completely nerded out on tuning but hammer spring an pellet weight only since it has an internal reg. I had established that this would be a sport for me and so more research on guns to see what I wanted as I am leaning towards bench rest as I am also a disabled vet in a wheelchair so PRS is probably not going to be possible.
After searching I narrowed it down to a Skout Epoch, Daystate Wolf of some kind or an FX impact, King or possibly a Crown for the right price with the right barrels. I found a used Impact M2 sniper config with the 480 bottle and a .22 cal 700mm barrel. I plan on moving up to the power block and 720 plenum but I was shooting it daily on a 70 yard range I set up in the yard with retrievable targets on a cordless drill driven paracord rig.
I shot it for a few days shooting 14.3 grain exacts at 963 fps +-5 with hammer spring on max and a reg reading of about 105 and then moved to the 18.13 grain JSB's because I had better accuracy with them in my Airacuda Max and was getting great accuracy (for me anyway). with the external knob thing tightened to two about 2.25 lines except for the occasional flyer I was dropping 9/10 under an American quarter at the end of the range and had quite a few sub MOA at five shot groups that fit under a dime at 70 yards and 100 shot strings on a fill with +- 4 FPS.
Problem
But I knew I wanted to reach out farther so I decided to up the reg a bit. I turned it a quarter turn and it immediately went to 150 bar and I thought well, that is higher than I wanted to go as a first step but lets try it.
It shot at 750 fps now? And that was with the wheel at Max so I was puzzled. I though maybe I have a light hammer and it cant open the valve enough? So I went from 2 lines of the nob on the return spring (I think that is what it is called) to four and still no luck. so I pulled the bottle, degassed the plenum even though it made me a bit nervous as I was aware that this could cause problems with gaskets suddenly in a relaxed position after being under pressure for years.
And then no matter what I did the plenum went to the bottle pressure after that.
So is it reg rebuild time or should I just try to replace the set screw O ring first before bringing the reg all the way out for a full rebuild?
What do I need to do to take the set screw out after degassing? I saw the rebuild video for the M2 by AoA and they were taking the trigger apart and pulling the reg piston and stack out using compressed air that I don't have ready easy access to so if there is something I can try short of that I would like too.
And if I need too is there a way to get the stack and piston out wo using low compressed air? I mean I guess could use the can of computer dusting air for it unless I am told that that would be a bad idea.
It is an old gun, should i just get a new reg for it because this is likely to happen in the future and being efficient (read lazy) I like to make my future problems easyer to fix.
What say you Airgun Nation?
O.K. I am pretty sure I will get the same answer but I seem to be having a similar problem. I do have a couple caveats though. I bought a used an airacuda max to see if I liked the sport enough and I did. I am a physicist so I completely nerded out on tuning but hammer spring an pellet weight only since it has an internal reg. I had established that this would be a sport for me and so more research on guns to see what I wanted as I am leaning towards bench rest as I am also a disabled vet in a wheelchair so PRS is probably not going to be possible.
After searching I narrowed it down to a Skout Epoch, Daystate Wolf of some kind or an FX impact, King or possibly a Crown for the right price with the right barrels. I found a used Impact M2 sniper config with the 480 bottle and a .22 cal 700mm barrel. I plan on moving up to the power block and 720 plenum but I was shooting it daily on a 70 yard range I set up in the yard with retrievable targets on a cordless drill driven paracord rig.
I shot it for a few days shooting 14.3 grain exacts at 963 fps +-5 with hammer spring on max and a reg reading of about 105 and then moved to the 18.13 grain JSB's because I had better accuracy with them in my Airacuda Max and was getting great accuracy (for me anyway). with the external knob thing tightened to two about 2.25 lines except for the occasional flyer I was dropping 9/10 under an American quarter at the end of the range and had quite a few sub MOA at five shot groups that fit under a dime at 70 yards and 100 shot strings on a fill with +- 4 FPS.
Problem
But I knew I wanted to reach out farther so I decided to up the reg a bit. I turned it a quarter turn and it immediately went to 150 bar and I thought well, that is higher than I wanted to go as a first step but lets try it.
It shot at 750 fps now? And that was with the wheel at Max so I was puzzled. I though maybe I have a light hammer and it cant open the valve enough? So I went from 2 lines of the nob on the return spring (I think that is what it is called) to four and still no luck. so I pulled the bottle, degassed the plenum even though it made me a bit nervous as I was aware that this could cause problems with gaskets suddenly in a relaxed position after being under pressure for years.
And then no matter what I did the plenum went to the bottle pressure after that.
So is it reg rebuild time or should I just try to replace the set screw O ring first before bringing the reg all the way out for a full rebuild?
What do I need to do to take the set screw out after degassing? I saw the rebuild video for the M2 by AoA and they were taking the trigger apart and pulling the reg piston and stack out using compressed air that I don't have ready easy access to so if there is something I can try short of that I would like too.
And if I need too is there a way to get the stack and piston out wo using low compressed air? I mean I guess could use the can of computer dusting air for it unless I am told that that would be a bad idea.
It is an old gun, should i just get a new reg for it because this is likely to happen in the future and being efficient (read lazy) I like to make my future problems easyer to fix.
What say you Airgun Nation?
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I guess I am asking if I can just do this first and can I remove the set screw without messing wit the rest of the things you have to when you are taking the whole regulator out.
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Hi etothen. Yep -- now that you have removed the bottle tank and bled the air from the rifle, you can simply unscrew the regulator set screw all the way and pull it out. If the only bad O-rings in your FX AMP regulator are the ones on the set screw, then you can get back up and running by replacing those two set screw O-rings and replace the set screw -- no need to remove the whole regulator housing.
Edit: When I said "replace the set screw", I meant to just screw the set screw back into the regulator with the new O-rings on it -- not buy a new set screw. I figure you knew that, but I could see where my wording was not the best there.
The regulator set screw O-rings get cut and torn pretty easily compared to all other O-rings on the rifle IF one does a lot of regulator pressure adjustments while the gun is aired up. The invention of externally adjustable regulators is convenient -- but is frickin' torture for the set screw O-rings. Imagine airing up your Impact and, while still under pressure, you grab the quick disconnect part of the hose and spin it around without bleeding the line first. Yeah, that's basically what the set screw O-rings are experiencing sometimes. The only difference is that set screw O-rings are well lubed (hopefully).
stovepipe
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Something I don't understand, if my plenum is open to the bottle why does it not degas when take the bottle off? And the remaining gas does not come out when I dry fire the gun, it remains under pressure and shoots extremely slowly even though the plenum is showing 170 bar reg pressure? Like the hammer cant bang the plenum open enough to get the gas out and it will keep doing that for about five shots that then follow a speed curve with the fastest shot at shout four and then it finally degasses like it should. The high pressure making it so the hammer cant open the valve enough seems to fit with the multiple degas shots but with the plenum open to the bottle why does the plenum start loosing pressure when I remove the bottle. I let it sit like that for an hour and it did not move, stayed rock solid at 150 at the time.
I just really wish I knew what I was looking for before I pull the whole reg so I have a better idea of what I am looking for. I prefer to do the research once so I only have to take everything apart the once but I have not been able to figure out a logical point of failure that would give this set of, for lack of a better word, symptoms.
I just really wish I knew what I was looking for before I pull the whole reg so I have a better idea of what I am looking for. I prefer to do the research once so I only have to take everything apart the once but I have not been able to figure out a logical point of failure that would give this set of, for lack of a better word, symptoms.
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Hi etothen. I have questions for you. There are pieces of information missing from what you've described that I need to help diagnose the problem.
First of all, are you sure you have an FX AMP regulator in that impact? If it's a HUMA regulator, then I can't help.
Assuming that it's an FX AMP regulator:
There are places where you mention what the plenum pressure was, but you do not mention what the tank pressure was.
For example, you said you increased the regulator pressure and the plenum pressure jumped up to 150 bar, but you didn't say what the tank pressure was at that time. If the tank pressure was also 150 bar at that time, then you may have actually set the regulator to some unknown amount above 150, but that's all the tank had in it at the time. If that was the case, then the regulator was doing exactly what it should do.
Another example is where you say the plenum pressure was 170 bar, but you didn't say what the tank pressure was at the time. If the tank pressure was, for example, at 200 bar, then that would indicate that the regulator is set to 170 bar and the regulator is doing what it's supposed to do.
Your observation that a high plenum pressure and a weak hammer setting is normal in that it would take several dry fires to finally drop the plenum pressure enough below the regulator set pressure to allow the piston to back away from the tiny hole in the end of the set screw and let air from the plenum to escape out to where the bottle connects to. This is normal behavior for an AMP regulator.
Your observation that when you removed the bottle tank, the plenum pressure didn't bleed out right away -- it required dry firing to drop the plenum pressure below the pressure that the regulator was set for. This is normal behavior for an FX AMP regulator.
Initially you said that you thought you were having a similar problem to that of the original poster, but this doesn't sound like the same symptoms. So far it sounds like your regulator is working as it should.
I did say that, IF the only problem with an FX AMP regulator was bad set screw O-rings, then you could bleed the air from the rifle and remove the set screw and replace just those two O-rings and re-install the set screw to fix the problem without needing to remove the entire regulator housing -- and that is STILL true. But I'm not saying there is anything wrong with your set screw O-rings -- so far, I just don't have proof that the O-rings are bad.
If you have more info that would help with a diagnosis, let us know. Cheers.
stovepipe
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It is an AMP regulator as far as I can tell, hex head not screw driver, looks internally exactly as expected given the AoA FX AMP rebuild video.
The reg pressure was set at 107-109 'ish, then I turned the set screw an eight of a turn and the plenum reg pressure jumped to 150 which was the bottle pressure at the time. So I pulled the bottle off and dry fired to drop the plenum pressure to zero and reinstalled the bottle and the plenum pressure jumped back to the bottle pressure. So I did this a couple more times as a kind of control alt delete for regs and the behavior continued.
So next I put the bottle on and hooked it up to the pump (unrelated side note below on this btw) and the plenum pressure followed the bottle pressure up to 180 before I stopped the pump, removed the bottle and dry fired until the plenum was completely empty.
Then I tried screwing the reg probe in until I just felt it touch something, about two and a half turns and I attached the bottle again and the plenum reg pressure again showed the same value as the bottle. So it looked like the plenum reg was stuck open, but it did still hold pressure when I took the bottle off. I was surprised that it looked open, but only one way?
So I gave in, went to the AoA site video on the M2 reg rebuild and removed the reg, inspected the piston, surfaces and O rings and found that everything looked lie it should with the notable exception of a lack of grease. I lubed the reg parts up, but only with silicone oil and then and reassembled it as per the instructions with the one problem being that I tracked the washers but I did not see any difference in color in the last two counter to the instructions in the Reg breakdown video describing them as Black, they were the same color as the rest of the washers?
When I attached the bottle the plenum pressure still followed the bottle pressure. But now when I detached the bottle the plenum pressure dropped to zero so I hade at least changed that. So I ordered some thick silicone grease and a new set of O rings. I suspect that they were the original rings and that they had not been adjusted or lubricated with grease in a very long time and doing anything to them made them give up.
So I have experience building/rebuilding and maintaining scientific equipment including gas chromatographs (I am atheoretical/computational climate physicist that has had enough practical experience with machinery that I am quite handy on the experimental side) and in my experience the surfaces I inspected looked like they were in excellent condition, the washers looked and acted exactly as expected and I suspect that the O rings are the likely suspects so I will carefully pull it apart, grease it liberally, install new O rings (although I am not looking forward to that one inside the block even though I have the perfect flat spade shaped dental probe that I bent into just the right shape to get into that 'ringland' so here's to hoping) and see what happens.
If it works, great, if not, well it is only 11 dollars wasted on the new O rings and I will re-asses then. I would point out that finding AMP regulators to replace or rebuild it has proven problematic and if I cant figure out the sourcing problem I may end up wit a Huma regulator for that reason. If you know where to find AMP regs and or rebuild kits let me know.
I hope I properly, sequentially and adequately addressed your questions with my lengthy diatribe about my regulator problems and would love any information about what was happening and exactly where I blew it because there was an easyer fix I missed lol.
PS. It was probably replacing the pin O ring next to it's head wasn't it?
*I have just started this hobby again after a couple decades and am new to PCP's and have been shocked by the pressures these little instruments work at and further shocked that I could get a, so far, reliable pump for $150 that will regularly pump them up too 300+Bar.
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Hi etothen. Thanks for the info -- all good info. From what you have experienced, I'd say it's definitely the O-ring on the set screw that is closest to the piston that needs to be replaced that was allowing air from the tank to flow directly to the plenum. The weird symptom that made that diagnosis uncertain was the fact that the plenum would not just bleed air back out of the "tank hole" right away (or at all) by removing the bottle tank. It's not that weird, though. Most O-rings that are set in a groove are only there to keep air from going past them in a certain direction, so there is a "down-wind" side of the O-ring and groove that takes a beating -- especially a set screw O-ring. So the set screw O-ring near the piston has never in it's life had to keep air from going the other direction -- that is until now. So when removing the bottle tank, that set screw O-ring was being pushed to the "never-before-used" side of the O-ring and groove -- so it actually held air because it was using the shiny new(ish) side of it. You coaxed it into giving up it's very temporary appearance of being a good O-ring by removing the set screw, oiling it, and re-installing. THEN it showed its true colors -- bad O-ring.
You mentioned the word "washers" a couple of times (the color of them). I'm quite sure you meant to say O-rings. When talking about a regulator that has belleville spring-disk washers as a primary component of the assembly, the word "washers" means belleville washers. Say O-ring if you mean O-ring. It'll help on this forum. The O-rings that you checked for black vs green or red color -- don't worry about the color as it's not a definitive guarantee that the O-ring is an NBR70 hardness (softer) or NBR 90 hardness (harder). Sometimes they are both black -- just depends where they were sourced from.
I guess, since you've had the whole regulator body out of the rifle and inspected it, it would make sense to replace all of the regulator O-rings. You seem to be adept at this "tiny finicky irritating parts" thing.
Regarding using silicone GREASE to slop your newly-built regulator with -- I went through an FX AMP regulator rebuild on my FX Maverick a few months back. I had previoiusly rebuilt it using silicone GREASE and, Man, what a mess. It wasn't just the mess of it, but I really feel that grease just gets pushed out of the way by the O-rings it's passing through and the grease doesn't "wick" back to where it's needed. So I followed the advice of AGN member "hogkiller". He loves Mobil 1 motor oil for many airgun lube jobs -- and now I do to. I wanted an oil that was going to "creep or wick" back to the O-ring that tried to wipe it away. I happened to have a little Mobil 1 5w-30 in my garage and that is what I liberally slopped on every part of my regulator. I know this is kind of off-subject, but I just want to spare you the yucky grease experience and give you my "theory" about why I don't use grease anymore.
As far as sourcing FX AMP regulator parts, I don't really know these days since I've not needed any new parts for a long time other than O-rings that I already got every one of that was listed on my schematic parts list from a web site called "o-rings-and-more". They don't sell them by ones and twos, they sell you a bag of a given O-ring, but I don't regret buying a lifetime supply of O-rings for my Maverick.
stovepipe
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AMP regs work fine, if you have a clue as to what to do and what NOT to do. IN the clue part, get the proper 0-rings, do not use silicon oil, use regular synthetic on the o-rings, and NO the gun won't blow up. Make sure you have THE latest brass parts. Match the Belleville washers for thickness, oil them too and a light polish on contact surfaces, I've written extensively on this, it's part of consistency, all Belleville's working equally. Do not try to decrease the pressure with out draining the system...BUT...and you didn't hear it from me...you can do it in very small increments quickly after firing, enough to fine tune. Neither of my Mavericks have had a lick of problems with reg creep over shot strings This graph is from my Maverick .25 a few weeks back, I don't remember when I rebuild the regs last.
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