Thanks thane - I'll be sure to check that out. I'm going to de-pressurize it in the morning and then pull it apart again to check all of the aiir passages.
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New SPA Artemis PP750
- Thread starter RJGTA
- Start date
i do not have modified regulator setting , i mean not yet ;-), but concerning the hammerspring, i agree with you the hammer spring is so strong, i have a range of 10m/s only, i have ordered some spring to test because i do not like the way he act.
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concerning the trigger, i replaced the first in front of trigger with a longer one the pull seems better, i do not have tool to test if it's in my head or a really data
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Do you mean you replaced the screw in the front of the trigger?
I don't think that screw on the inside adjusts the regulator. When you take it out and look at it, it appears to just be an air pass through with a filter - I don't see how it would adjust anything. Once you pull the whole regulator apart you'll see what I mean. I'll post a picture later when I get back into it.
I don't think that screw on the inside adjusts the regulator. When you take it out and look at it, it appears to just be an air pass through with a filter - I don't see how it would adjust anything. Once you pull the whole regulator apart you'll see what I mean. I'll post a picture later when I get back into it.
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Brass flat blade adjusts regulator pressure by reducing or increasing the little plastic seal against small air passage. Clockwise increases pressure on seal against spring stack which lowers the output pressure. Counter clockwise reduces spring tension against seal, increasing output pressure.
A small amount of cw or ccw makes a big difference. If you are out of range setting changes will appear to have no effect. Mine was made even more difficult with a rogue silicon bead in the washer stack, I couldn't get it to settle down at all. Once removed, belville washers edges polished, mirror polished the cylinder walls the regulator piston orings contact the reg is very consistent with no creep and fine tune adjustable.
Take you time, 1 quarter CW turns in at a time, repressure, chrono, repeat until you get an velocity drop... your in range for adjusting the reg. Full turns are way too big, you will pass the whole range. I punched a dimple on the brass and regulator body to index adjustments, otherwise hard to track.
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Thanks thane. Guess I'll be going through a lot of air.
Have you found an easy way to depressurize the tank aside from just shooting it down? I notice that once it get's below 70bar the valve just leaks out whether the hammer is pushing on it or not - weird.
Oh - and based on what you are saying - if I didn't have the brass screw in at all then the reg would be pushing it's max psi - is that an accurate statement?
Have you found an easy way to depressurize the tank aside from just shooting it down? I notice that once it get's below 70bar the valve just leaks out whether the hammer is pushing on it or not - weird.
Oh - and based on what you are saying - if I didn't have the brass screw in at all then the reg would be pushing it's max psi - is that an accurate statement?
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Yep, you got it, backed out brass screw would let the air free flow passing the seal, making the same pressure on both sides, max pressure. The washer stack adds to the output side pressure in closing the seal.
Spa provided a air gauge socket tool in my box. I just back out the air gauge slowly until it starts to vent, hard on the oring so have spares on hand.
As far as a leaking out at 70 bar the brass poppet on brass seat seal needs quite a bit of pressure to maintain a seal. You could mate them with some lapping compound and a drill or lathe to make a better seal, but 70 bar is a very low pressure to be operating at. It would certainly make a hand pump fill difficult to impossible.
You should inspect your brass poppet for a crack. The poppet wall is 0.1mm thick where the shaft is and mine let go, replaced with much stronger PEEK poppet, lapped to brass seal. I used a lathe, but anyone could make it with a hand drill.
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Sorry - didn't mean to confuse - that was two statements.
1 - the screw at the trigger being longer in front.
2 - the screw in the regulator.
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hello, I also had the broken plastic valve and I replaced it with one from cp1 that I had (what reference for the valve you used?)
can you tell me the number of turns it takes for the regulator because i disassembled it and i did not spot anything lol
thank you
can you tell me the number of turns it takes for the regulator because i disassembled it and i did not spot anything lol
thank you
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The plastic PEEK poppet/spring seat was machined from rod stock, not a pre-manufactured part. The plastic spring seat became unneccesary since the PEEK poppet was shaped to serve both purposes.
Because the belleville washer stacks would vary from gun to gun turns would also be different. If you have a sensitive hand you could back it out CCW a couple turns, then carefully start turning in CW until you feel tension (seal coming into compression). Chrono, de-gas, do another quarter turn CW, chrono... Take your time, it's worth hitting the right set point for the velocity and pellet that works best. You will end up with an air efficient tune with low extreme spread.
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thank you for the info, for now I have revised the regulator to the maximum it works well but as I do not have a chrony I can not know the power, for the number of shots I have not yet done the tests.
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paco - what I have realized is when you set the reg to "maximum" you are really in bypass mode. So if you fill to 200bar your shot will be very slow as that's a lot of pressure on the valve.
thane - I took a few tries but I think I found the point where it is on reg. It's taking a lot of pellets and patience (and an irritated wife - thump, thump, thump - what on earth are you doing down there? lol).
I'm thinking of cutting down a metal rod to fit between the hammer and the HS adjustment screw. Then I can just remove the HS, insert rod, tighten and open valve to depressurize. Any reason that might not work?
thane - I took a few tries but I think I found the point where it is on reg. It's taking a lot of pellets and patience (and an irritated wife - thump, thump, thump - what on earth are you doing down there? lol).
I'm thinking of cutting down a metal rod to fit between the hammer and the HS adjustment screw. Then I can just remove the HS, insert rod, tighten and open valve to depressurize. Any reason that might not work?
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De-gas rod is a great idea, save a few orings!
It takes a lot of reg setting changes, full air charge shoots, reset reg, shoot string again... eventually you will find that flat string at your velocity target. So picking the best performing pellet first, fortunately mine isn't very pellet picky. Four dry fire to one pellet can save some led.
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I'm just not a fan of the pressure it puts on the last few threads as you unscrew the gauge. And tearing up the o-ring kinda sucks too.
I've been slowly turning the screw in to lower the reg pressure 1/8 CW at a time. What I am seeing is the stock limits on the gun are prevent me from getting above ~730 with JSB 10.34 gr pellets. I was trying to see if I could flatten out the shots by getting it up to 800 fps. But apparently it just doesn't seem possible with this gun combined with my limited knowledge and tooling. The plenum seems on the smaller side as well. What I do know is that I have turn the reg screw in a good amount from the stock setting and I am still able to get a 720fps max with a final setting lowered to 700fps.
I was getting about 5 mags worth of air when the gun was stock. Definitely is shooting quieter with the lowered reg setting and it looks like I shot through about 20-25bar on one mag. I'll shoot down the gun to 110bar and see how many mags total.
I've been slowly turning the screw in to lower the reg pressure 1/8 CW at a time. What I am seeing is the stock limits on the gun are prevent me from getting above ~730 with JSB 10.34 gr pellets. I was trying to see if I could flatten out the shots by getting it up to 800 fps. But apparently it just doesn't seem possible with this gun combined with my limited knowledge and tooling. The plenum seems on the smaller side as well. What I do know is that I have turn the reg screw in a good amount from the stock setting and I am still able to get a 720fps max with a final setting lowered to 700fps.
I was getting about 5 mags worth of air when the gun was stock. Definitely is shooting quieter with the lowered reg setting and it looks like I shot through about 20-25bar on one mag. I'll shoot down the gun to 110bar and see how many mags total.
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Between the 8" barrel, small plenum and 3mm ports it tough to break 12 FPE.
I opened all the ports, epoxied the channel around the barrel transfer port, aligned barrel transfer port, bored out plenum and extra 1.5mm, channels in the hammer, peek poppet, polished reg... only got me to 775 fps 13.6 FPE with the 10.34 and 825fps with JSB 8.4 in a decent 26 shot string. Dropped the scope to 1.3" above bore, reduced velocity to 750 with the JSB 8.4 for 30 shots within 1.6%. It's making 1/4" groups at 25 yds and super quiet. Already blooded in with a rat and a hosp, I will be operating in this range for a while, PP750 is great at 10-35 yards.
I opened all the ports, epoxied the channel around the barrel transfer port, aligned barrel transfer port, bored out plenum and extra 1.5mm, channels in the hammer, peek poppet, polished reg... only got me to 775 fps 13.6 FPE with the 10.34 and 825fps with JSB 8.4 in a decent 26 shot string. Dropped the scope to 1.3" above bore, reduced velocity to 750 with the JSB 8.4 for 30 shots within 1.6%. It's making 1/4" groups at 25 yds and super quiet. Already blooded in with a rat and a hosp, I will be operating in this range for a while, PP750 is great at 10-35 yards.
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