S510 power adjustment screw creeping?

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tonyc
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S510 power adjustment screw creeping?

Thu Jul 12, 2018 6:34 pm

The power adjustment screw on my 510 seems to be on the loose side in the position I want it set. When I've taken the cap screw out and wound out the adjuster it becomes stiffer. But I put the cap screw back and took it out again a few days later to find the adjuster appears to have gone back to its loose postion. I'm not sure if the adjuster is creeping or if cap screw is too long and is making contact with the adjuster and turning it as I put the cap screw back in. I've thought about putting a spot of blue Loctite on the adjuster but want to check first if anyone had any helpful comments or suggestions.

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Roger5
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Re: S510 power adjustment screw creeping?

Thu Jul 12, 2018 10:10 pm

tonyc wrote:
Thu Jul 12, 2018 6:34 pm
The power adjustment screw on my 510 seems to be on the loose side in the position I want it set. When I've taken the cap screw out and wound out the adjuster it becomes stiffer. But I put the cap screw back and took it out again a few days later to find the adjuster appears to have gone back to its loose postion. I'm not sure if the adjuster is creeping or if cap screw is too long and is making contact with the adjuster and turning it as I put the cap screw back in. I've thought about putting a spot of blue Loctite on the adjuster but want to check first if anyone had any helpful comments or suggestions.
Hi Tony, if you get a new power adjuster screw RN191 it comes with a spot of blue loctite, and the cap screw doesn't normally touch it, they can screw themselves in reducing power or they can wind themselves out putting power up, I have heard ot people using a second RN191 to lock the first, but I never have, blue loctite should do it, be lucky. Rog

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TenMetrePeter
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Re: S510 power adjustment screw creeping?

Fri Jul 13, 2018 8:43 am

The dust cover screw that replaces the anti-tamper should only have a few threads on it too. Purple loctite 222 is the weakest and will "allow adjustment and easy disassembly".
Blue allows disassembly with "some difficulty." Grub screws are notorious for stripping the hex socket under stress.
Don't use high strength (red usually) or you may as well weld it in!

(I once designed conveyors with sprockets high strength loctited onto 25mm shafts instead of keyways and they shifted truck cylinder blocks. Old time fitters just didn't believe it!)
S400 MPR 10m with TMP alloy stock.
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tonyc
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Re: S510 power adjustment screw creeping?

Sat Jul 14, 2018 12:25 am

Thanks guys. I'll get some Loctite 222.

Roger, I still haven't adjusted the reg pressure yet. But I'd seen a further reduction in velocity so I thought I would just check the power adjuster first. Wound it out a bit and, hey presto, back up to 772 fps. But the reg is still set too high. Altaros now have new video (or maybe it's an old one I couldn't find/open earlier) and comments about reg pressure creeping up. It would seem this is a necessary periodic adjustment due to regulator spring ageing and gradual build up of contamination on the adjuster internal o-ring. The video covers cleaning/replacing the o-ring.

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TenMetrePeter
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Re: S510 power adjustment screw creeping?

Sat Jul 14, 2018 9:49 am

Just from a metallurgical view a spring that hardly moves and stays roughly at ambient temperature should never get weaker.
Just getting my head around it but would not a weaker spring give lower pressure anyway? Pressure fights the spring to close the valve. Weak spring, valve shuts earlier?
Bad seals that let in air after the reg has closed would be suspect.
Does the gauge creep up over time?
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Archer50
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Re: S510 power adjustment screw creeping?

Sat Jul 14, 2018 3:00 pm

I'm quite a fan of Altaros regulators, but the four I know fairly well do creep upwards with time. Judging by the inbuilt pressure gauge (I don't have anything better) my own, in an S400, crept about 5-10 bar in a year or so. Certainly the average MV for 8.4 Air Arms pellets crept from 772 to 780. I hadn't seen the new video, and simply adjusted the reg down again - which is very easy to do. I will try cleaning the reg next time I have the gun apart, but the creep is very slow and I keep my guns well under max so it's not an urgent issue for me.

A friend has had an email from Ondrej where he suggested that the best way to prevent the creep is to reduce cylinder pressure to around the reg pressure (100 bar) to store the gun. Unfortunately, the original email has been lost, but my friend said that he thinks the reason given was to avoid compressing a nylon component. Anyway, it's easy advice to follow, so we are keeping our eyes on whether it improves the problem.

Alan

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tonyc
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Re: S510 power adjustment screw creeping?

Sat Jul 14, 2018 9:23 pm

;)
TenMetrePeter wrote:
Sat Jul 14, 2018 9:49 am
Just from a metallurgical view a spring that hardly moves and stays roughly at ambient temperature should never get weaker.
Just getting my head around it but would not a weaker spring give lower pressure anyway? Pressure fights the spring to close the valve. Weak spring, valve shuts earlier?
Bad seals that let in air after the reg has closed would be suspect.
Does the gauge creep up over time?
Just repeating what Altaros has on it's website - they say "spring fatigue" - and it causes the reg pressure to go up, not down. The end result is the power increases after the gun comes off reg, as normal bell curve, except the curve is accentuated relative to the unregged gun as there is no pot.

Alan. I'm seeing the opposite - power when on reg is falling as the reg pressure is higher than peak of the unregged curve. Maximum power is 11.4 ft lb with 8.44gr at 120-110 bar. If I had the reg set at 100 bar I would see power increasing as the reg pressure creeps up.

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Archer50
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Re: S510 power adjustment screw creeping?

Sat Jul 14, 2018 10:48 pm

Tony, I'm not trying to teach you to suck eggs, but I suggest you go back to the basic, recommended set up and work from there. First set your reg to the 100 bar recommended by Altaros for standard, S-series guns (trial-and-error if you haven't got a reg tester, but not difficult). Then install exactly as in the Altaros video. This should let you see if the reg is working properly at its design pressure, stays stable, has no leaks etc. Assuming the 510 has the same cylinder capacity as the 400 It should give you a shot count of around 70 regged shots. If the reg creeps perceptibly, I would clean it and replace the o-ring. In fact you might want to do that anyway.

If this is ok, leave it there. If you want more shots, I would collapse one coil of your hammer spring, set the power adjuster so it is completely open, and adjust the firing valve spring to give the power you want - you shouldn't have to use the power adjuster again. There are other ways of doing it, but I have found this way to work well and with a bit of fiddling, it should give you around 100 shots.

Personally I always lock the power adjuster screw by putting a 3 x 3 grub screw behind it - I don't use Loctite and I don't rely on the blue nyloc patches on the newer adjustment screws.

Good luck.

Alan

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TenMetrePeter
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Re: S510 power adjustment screw creeping?

Sun Jul 15, 2018 7:18 am

Tony, read what Alan said. I am an armchair gunsmith.

Just for my own peace of mind though, to increase regulated pressure do you not wind up the screw and increase the pressure on the spring?
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Roger5
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Re: S510 power adjustment screw creeping?

Sun Jul 15, 2018 9:58 am

TenMetrePeter wrote:
Sun Jul 15, 2018 7:18 am
Tony, read what Alan said. I am an armchair gunsmith.

Just for my own peace of mind though, to increase regulated pressure do you not wind up the screw and increase the pressure on the spring?
Clockwise decreases reg pressure,anti-clockwise increases. Hope that's a comfy armchair Peter :) Rog

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