Fx impact reg problem

[Eddy1840]

i have my reg set at 125 bars, when I take a shot I takes more then 10 minutes to reach 126 again, so decided to take it apart and found on the piston a little dent on the edge where the o'ring sits here is a picture 

can it be causing the problem?

 

[Birdslayer25]

I wouldnt think that would cause your problem. Make sure nothing is inside the tiny hole iside the piston. Take wire off a wire brush that what i did. 

 

[AirSupply]

Hi Eddy. When you say it takes 10min to achieve 126bar. Is it just the last few bar that take that long or is it slow and gradual throughout the recharge?

If it’s just the last few bar it could be creep. Take a look at the small end of the piston does it have a divot that looks pressed into the centre? 
This is the sealing surface and should be flat and smooth. You will sometimes see very small marks but not a hole or divot. 
Thats the most likely problem which requires a new piston to fix. 

 

[riazp]

Creeping!

Things to check while you have it apart:

The piston likes to be smooth where the washers go, have seen gouges on some, 1200 grit very carefully only where the washers ride! Better yet is 3m pink or blue fabric. We are talking about polishing not taking material off!!!

The sealing surface should not have any divots, small dent it OK, gouging is bad. If you feel brave the divot can be resurfaced with 1200 grit and a glass surface. Put Paper grit side up on glass, place piston on paper, press piston lightly onto paper and maintain the perpendicular orientation, now rotate the paper under the piston a few times. The standard piston is 14 mm long, don’t grind of more than .03 of a mm, if you do just get a new piston. When done make sure the inlet and outlet hole are clear.

The adjuster screw has a knife edge, it’s too sharp, the sand paper trick above can be used to gently reduce the edge from razor sharp to rounded dull edge, try not to file off more than half the overall height of the cone with the hole.

How many washers and what order were they in? One can debur those, inside edges, outside edges inter washer contact points, polish the surface. The washers are compression springs so you are looking for nice sliding surfaces.

How many shots have you fired, I did the above to my reg after about 15000 rounds, worked very well, best results were achieved by addressing the piston divot and knife edge.

Spares take forever to get to South Africa, so I DIYed it until a new piston and washers arrived. The new washers were polished and deburred, I then used 12 instead of 11 arranged like this ()()()()()() instead of like this )()()()()(), my adjuster screw is flattened already so the new combo is very consistent.

I shot a few thousand pellets and inspected the reg to find no more gouging, yay! Now after the reg settles I can leave it overnight and find the reg at the same pressure the next morning.

If I lived in the US I would call Ernest, order parts and just replace as the procedure above will void your warranty, is frought with danger and only for those willing to completely ruin the parts being worked on.

 

[Eddy1840]

Thank you guys for all the tips, I installed a new o'ring on the piston and cleaned the holes on the piston and adjuster screw also cleaned the washer very well.. I have the reg on 120 now, I went outside and shoot it 36 times the high was 902fps and the low 890fps the temperature was 34* then i came inside after one hour I checked it and it was 128 brs, the temperature inside my house is 70*. Is it normal? I dry fired it and came down to 120brs .. Does the change of temperature be causing it?

 

[shutik]

Yes, change to warmer temperature will increase pressure and change to colder temperature will decrease it.

Pressure in regulated chamber was at 120 at cold temperature and when you brought it inside and it warmed up pressure increased from change in temperature. 

 

[sirk]

discharge it, then monitor it long term in stable temperature to see if it creeps

looking at that piston, who has worked on that looks like it got damaged, they dont come from the factory like that

 

[Eddy1840]

Thanks guys, it's fixed.

 

[toku58]

"Eddy1840"Thanks guys, it's fixed.

So what exactly ended up to be your issue? How did you finally fix the problem?

 

[John "spysir" Blount]

x1
John

 

[Drumsnguns]

Yes, Eddy 1840, don't leave us hanging. What exactly "fixed" your problem? I too am having a regulator creeping problem.

What are you guys cleaning the belville washers with? 3M cloth? If so, Which color and are you just rubbing between fingers? are you chucking the pistons up in a drill to polish?

Any info will be helpful to the rest of us.

Thanks,,KP

 

[Eddy1840]

I work polishing jewelry, I took the whashers and polished them, then I cleaned the hole on the piston with a tiny wire and installed new o'ring. It's not creeping anymore but now my hand pump broke down.. 

 

[Drumsnguns]

I was wondering if you could be more exact. Do you use a dremel, if so what tip do u use. Just trying to get some good info so I don’t screw anything up and have to buy new parts. The cost is not an issue but tracking down the parts, trying to get people to answer phones and the waiting a week to get a 2 dollar part you paid 10 bucks shipping for is what I’d like to avoid. Any info appreciated 
KP 

 

[riazp]

A good set of micro hand drills for the holes, 1200 grit for contact surfaces between washers, I used the pink fabric to buff the washers. No dremmel on delrin, it melts, the piston seals at three place so I ovaling it with a dremmel renders it useless.

Robert Lane on YouTube is an absolute must see if working on regulators is to be done, Earnest as well..

 

[Drumsnguns]

Just wanted to say that due to the cold weather/snow out here on the east coast I finally tore into the Impact and polished up the regulator piston rod and the belleville washers. Not sure I did as thorough a job but used the 3M paper to get everything nice and smooth. I got it all back together and short a string over the chrony on hammer spring setting B which I have been having some good luck with lately. The reg is right around 120 bar. Here is the string shooting unsorted/unweighed Heavy MKII:

848
840
848
849
848
848
841
851
849
851
846
Ave: 847
ES: 11
SD: 2

I hope that it's not a fluke. Other settings weren't quite as good but still they were very good. More likely the spring characteristics at diff. settings than the reg. I'll bet with weighed pellets the numbers would be even better.

Before the cleaning/polishing my ES/SD averages were 12-15 and 3-4 which was still decent.
Gonna be checking for creep over the next few days or until the weather allows me to go outside and get to shooting again.

Thanks for the tips guys, really helped.

KP

 

[Eddy1840]

Glad to hear that, I didn't use my impact since then. I have been working but can't wait to go outside and try it at longer distances.