Tuning Huma vs amp regs

in my dreamline .25, i purchased a huma reg, after using it, and playing with the tune and such, i ended up going back to the amp reg. the external adjustment is super nice, compared to dumping the tube, and yanking the reg out to adjust it.

my huma was a creeper, too. i swapped out the disks, and orings, lubed it right, and the amp is still more consistent for me. It does take up more space, but with the plenum spacer on there, its not a big deal to me.
 
I have an Impact-X with the predecessor of the AMP reg on it. It werqs just as well as my Huma. Huma actually states on their site that their regs will perform pretty much the same as a good werqing stock FX reg. I like the Hex adjustment on the FX reg much better than the Huma slotted unit.

I agree! The biggest thing that I noticed was how fast it refills the plenum.
 
For those that have used both, I have a couple questions:

1) Is the refresh speed similar between the two or is one faster? (And which pressure range spring stack are you using on the Huma?)

2) Has anyone monitored set point shift due to temperature changes on the Huma? 



Really hoping someone has data for #2. Now that I have an angled manometer bracket and Sekhmet gauge on the second reg, I'm hyper aware of reg changes. The plastic piston in the AMP definitely contracts in the cold and raises the set point. Between 70deg and 40deg F I'm seeing an increase of about 10bar. It is very predictable though, and when you return the gun to a previous temperature environment, it will return to the set point dictated by that temperature. Fairly easy to deal with especially on an M3 where you can add a couple clicks with the micro adjuster to compensate, and keep your speed the same, but that doesn't mean I don't need to investigate if the grass is greener on the other side! This is the only real issue I have with the AMP.







I'd like to provide some interesting belleville washer info since I did a deep dive on them and the different strategies FX and HUMA took. Washer size for both AMP and Huma regs is 10mm since the space constraints are the same regardless of reg (at least for the Impact). In 10mm diameter, there are three available belleville spring thicknesses. Here they are along with the maximum force for each in Newtons:

0.4mm = 232N

0.5mm = 377N

0.6mm = 652N

Just to simplify discussion lets call this stacking "single stack": ()()()...

and lets call this stacking "double stack": (())(())(())...

Huma uses stacks of same thickness washers and they have different washer stacks for different ranges. Huma uses a single stack of 0.6mm washers to give a pressure range of 135-200bar, and a single stack of 0.5mm washers to give a pressure range of 60-135bar. The middle range between between these two is where the challenge lies. Ideally, you want to avoid double stacks of belleville washers because the friction between washers can slow response. What we really need is a 0.55mm thick belleville washer, but that doesn't exist, so Huma chose a double stack of 0.4mm washers (2*232N = 464N total force) to give a pressure range of 110-165bar.

What did FX do? The AMP reg uses a single stack of washers, but made up of both 0.5mm and 0.6mm washers. My reg had 6 - 0.6mm washers and 5 - 0.5mm washers. I'd imagine this gives a progressive curve vs the linear stacks of Huma, and I'm sure it was done to try and achieve a 'one size fits all' spring curve covering the widest pressure ranges possible. From my brief reading on belleville springs, I get the impression that such a choice is somewhat unconventional, that an ideal design would have all matching springs, like Huma uses for all their pressure ranges.

Which spring strategy works better? Well I have a bag of 0.4mm thick washers I got from McMaster so that I could try out the Huma-style double stack for mid pressure range. I got those washers when I thought I had a reg issue, but it turned out I had a chunk of o-ring lodged in the passageway downstream of the reg. With that cleared out, the AMP reg has been working great, at 100 bar and at 150 bar. I see no need to tear things down at the moment, but maybe sometime in the future when I have the reg out I'll give it a shot. One thing that seems a no-brainer, is that if you are specifically running a really high or really low reg pressure, you'll probably get better performance using all 0.5mm or all 0.6mm washers like Huma is doing. You might even be able to take the AMP up to 200 bar with all 0.6mm washers, as long as it is only the washers that are the limiting factor (I have no clue, try at your own risk).



You can see Huma washer stacking info in this doc:

http://foto.huma-air.com/foto/Installation%20guide%20FX%20Impact.pdf



2-page doc on belleville spring engineering considerations:

https://www.apexfasteners.com/fasteners/images/BellevilleWashers.pdf






 
Replace the orings on ur amp reg, if the piston is damaged replace that too. Tune the gun to 95-97% of max power. Shoot some groups. 

I think most issues ppl have with fx reg come from bad tunes, trying to adjust speed with just the hammer spring.
My impact creeped 5 bar. Was tuned with a 145bar plenum, shooting 34g jsb pellets. Needless to say the first shot was always a miss. 

however, once I turned the plenum down to 100bar, tuned the hammer just shy of of max power. Creep no longer mattered. 
but as stated above, pretty easy fix on an impact 





 
Replace the orings on ur amp reg, if the piston is damaged replace that too. Tune the gun to 95-97% of max power. Shoot some groups. 

I think most issues ppl have with fx reg come from bad tunes, trying to adjust speed with just the hammer spring.
My impact creeped 5 bar. Was tuned with a 145bar plenum, shooting 34g jsb pellets. Needless to say the first shot was always a miss. 

however, once I turned the plenum down to 100bar, tuned the hammer just shy of of max power. Creep no longer mattered. 
but as stated above, pretty easy fix on an impact



I agree with your points on tune issues, but this case is most surely thermal contraction of the reg system, the likely culprit being the delrin piston (which others on here have commented on before). The reg is working as designed, and whatever minor creep I had before was eliminated after I re-lubed everything and polished the sealing surfaces per that Ernest video. I'm also shooting a 96% tune. The reg set point changes are amazingly consistent. Drop to 50deg, reg 155 bar. Drop to 40deg, reg 158bar. Back to 70deg, reg returns to 148b. Rinse and repeat the results have been the same each time i've subjected the gun to a temperature change. Now when I say 'reg went to 158 bar' for example, I mean with the gun at that temperature, if you cycle the reg it returns to 158bar every time. A solid set point change. Obviously if you take the gun from cold environment to warm without firing it, the plenum pressure will increase due to the air trapped in there, but once you cycle the reg in the new warm environment it will be back to the correct set point for that temperature. I'm solely concerned with set point changes.



I agree that small changes in reg pressure shouldn't matter, but 10 bar is going to matter, especially when you are chasing perfection and trying to shoot 100-200 yards :) And I haven't even gotten to the full hot/cold extremes yet. I've started a table of temperature, reg pressure, and micro adjuster clicks needed to compensate precisely, but I think a brass or titanium piston with 6x-13x less variance due to temperature may be the best solution. I'm just not sure I want to switch an entire reg design out merely to get a different piston material. If someone made a titanium AMP piston, I'd try it in a heartbeat.
 
Imagine the washer spring stack at a specific point of compression and the reg piston end is seated and closing off air input. Now imagine the piston instantly becomes shorter by a small amount (lower temperature has shrunk the piston material). The air input is no longer sealed by the piston end and air will begin entering the plenum and further compressing the spring stack until the end of the piston again seals off the input. If temperature were to increase the reverse would happen, with added catch that reg set point would not lower until after the first shot was fired clearing out the higher pressure that occured at colder temps.
 
Imagine the washer spring stack at a specific point of compression and the reg piston end is seated and closing off air input. Now imagine the piston instantly becomes shorter by a small amount (lower temperature has shrunk the piston material). The air input is no longer sealed by the piston end and air will begin entering the plenum and further compressing the spring stack until the end of the piston again seals off the input. If temperature were to increase the reverse would happen, with added catch that reg set point would not lower until after the first shot was fired clearing out the higher pressure that occured at colder temps.

The piston in the fx amp reg is nylon or black delrin 

And when temps go up, all my bottle pressures go up. Not just plenum. Including my large CF bottles. 
Air pressure increases at higher temps. 


 
If you go from cold to hot environment, the plenum pressure will go up (one time) because cold air trapped in the plenum will warm up and expand, and yes, this will further seal the piston. As soon as you fire your first shot in this hotter environment all that air is gone and the reg will refill the plenum to the set point pressure dictated by the piston to adjustment screw distance.

This is a 'pound of feathers weighs same as pound of lead' scenario once everything is equalized in temperature with the environment. The reg needs X pressure of air to push on the piston, and outside of the piston growing or shrinking, it doesn't really matter what temperature the air is that is pushing on that piston.