FX Crown/Impact regulator mod tutorial

Forums PCP Airguns FX Crown/Impact regulator mod tutorial

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    weatherby
    Participant
    Member

    Hey Guys,

    As a lot of you seem to be interested in the modification I did to my Crown regulator to prevent creep and improve the settling time, I decided to take my Crown apart to make a tutorial.
    disclaimer: Don’t do this mod when you are not feeling comfortable doing it, I can’t  estimate someone else’s technical skills, and you need to work very clean and precise. There is a risk of messing up the parts.

    Tools needed:
    Metric allen keys of good quality, sizes 2mm, 2.5mm, 3mm, 4mm and 5mm
    Size 11mm thin spanner (I had to grind one down to fit the narrow space between gauge and action.
    Artery clamp 
    Silicon grease.

    Step 1, remove the safety lever with a 2.5mm allen key:

    Step 2, remove the power adjuster wheel with a 2mm allen key (be careful not to loose the 2 ball bearings underneath the adjuster wheel)

    Step3, remove the stock (3mm and 4mm allen key):

    Step 4, remove the stock 

    Step 5, remove the bottle

    Step 6, If the reg. isn’t degassed yet, (see gauge) dry fire on lowest power setting of both power wheels until the regulator bleeds all air.

    Step 7, remove gauge (bottle pressure) 11mm spanner.

    Step 8, remove regulator adjustment screw (2.5mm allen key)

    Step 9, remove the regulator retention screw (5mm allen key)

    Step 10, remove the regulator piston (artery clamp) and make sure not to damage it, as it is Delrin (soft). I’ve put some tape around the noses of the clamp to prevent it from damaging.

    Step 11, stack the belleville washers in a different way
    original setup, 16 bv washers stacked like this: ()()()()()()()()

    my setup: |))(())(())(()) I started at the piston side with a drilled out and O.D. turned down m3 washer to prevent the sharp edges of the belleville washers from digging in the soft Delrin surface. Any fitting washer will do the trick, as long it is flat and fits the hole.
    The belleville washers are twice as stiff in this config, and the travel has decreased a lot.
    Note that my stack is shorter, with a longer stack the regulator piston could not reach the adjuster screw anymore, so the reg. could not be adjusted.

    Step 12, assemble in reverse order, and adjust reg pressure as specified by FX (but now you can run a higher reg pressure than FX’s recommended 150bar.)
    Note: all regulator parts should be assembled “finger tight”, the o rings will seal the parts, not the threads. Rather be on the loose side than too tight. Especially the regulator adjustment screw.

    As a bonus, my way of adjusting down without degassing: 

    When you dryfire a shot, the gauge of the regulator gauge takes a big dip in pressure.
    This dip normally takes about 1 second before the pressure settles again.
    In this second, the regulator piston is not making contact with the adjuster screw.
    So, within this second, I immediately turn in the reg adjuster screw about 1/8th of a turn.
    Now the regulated pressure will be down, and can be worked up to the desired pressure again.
    Works perfect and saves a lot of hassle (degassing)  

    Good luck, Gijs

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    jking
    Participant
    Member

    Gijs, since I have a Crown coming, I for one really appreciate the effort and well written and photographed tutorial. So you’ll end up with two spring washers being left out. Would it have been too to stiff with the last set added on the washer end against the  2 other singles? Definitely going to save this one to my favorites.
    Thanks again,
    Jimmy
     

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    bzizzi373
    Participant
    Member

    Thanks for taking the time to do this tutorial, I have the same set of Mitutoyo calipers and digital 0-1” mics
    in a case. I have lamanite Crown and have noticed a slight creep but so far really not that severe. However, I will do the mod to to eliminate any creep. I called FX and spoke to Earnst Rowe, he sent me all the O rings that the regulator uses and a couple belville washers along with 5 probe or breech O rings.
    He said working on your own FX Airgun will in no way void the warranty and actually encouraged it.
    I am a tool and Die maker by trade so I have access to a full machine shop, I have my own Bridgeport mill and Harding lathe that I use quite often. 
     

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    weatherby
    Participant
    Member

    @jimmy, I noticed when I made the stack the same length as original, the piston could not move far enough to function properly because of the more limited travel of the double stacked BV washers .
    Regarding stiffness, it doesn’t make a difference as long as you stack the BV washers in the same way. They work in pairs now, i.s.o. alone in the stock configuration.
    If you ad a pair, you are only increasing the spring travel, but not the stiffness. 

    @bzizzi, I studied tool and die maker as well, but now I do something copletely different. However, as a hobby, I have a microcut Lathe and a Micron Drill/Mill combination and I’m always trying to improve stuff. Too much fun :)

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    ashes5
    Participant
    Member

    I disagree with the not voiding the warranty. FX is pretty strict. I sent in my Impact to AOA under warranty and they checked it out to see if I had worked on it. that has been my experience.  

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    2D1C
    Participant
    Member

    +1 to you sir! I will be ordering my Crown Shortly. Book marking everything I see to aid in the my enjoyment.
    Looking forward to it immensely!!

    Thank you!

    Dennis

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    agnthooziast
    Participant
    Member

    Please explain what you mean when you say “creep” as I have a crown coming. Bill

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    weatherby
    Participant
    Member

    “agnthooziast”Please explain what you mean when you say “creep” as I have a crown coming. Bill

    
The regulator pressure creeping up from the adjusted regulator pressure, for instance, you adjust the regulator to 150 bar, and over time, it creeps up to let’s say, 170 bar.
    When you fire a shot, the pressure is at 150 again, but will creep up again instead of staying put at 150 bar. (very annoying…)

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    Michael
    Keymaster
    Keymaster

    Thanks for taking the time to share this!

    We’re working on a new image hosting plug-in that will allow users to upload multiple pics at the same time. 

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    bzizzi373
    Participant
    Member

    That was when AoA was the US importer and service center, AoA is no longer the importer and primary service center. FX opened up a USA distribution and service center in NC with Earnst Rowe heading up the service end. I got this info right from him. So according to FX USA if you repair gun yourself FX will send you parts no charge under warranty. This includes changing the regulator like Weatherby has done. 
    I would say the only way FX would void warranty if user extensively altered or modified gun.

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    RMORRIS
    Participant
    Member

    Thank you Weatherby. I would like to know if FX approves of this repair or if they have a better idea to address regulator creep in the Crown, Like a regulator upgrade kit  that the customer could install without voiding his warranty. If yours is the best fix  then Fx should send customers that washer with your instructions. Thanks again for your input on this topic, it gives me hope that I can fix my regulator.

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    lavahunter
    Participant
    Member

    Thank you so much for this.
    Had my crown for a week now and notice that every first shot after sitting a while is always 1/2″ low, so I must have some creep.
     

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    agnthooziast
    Participant
    Member

    +1 to RMORRIS’s take and resolution!

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    AirSupply
    Participant
    Member

    Hey Gijs, thanks for taking the time to explain your modification. I did this to my Crown a couple of days ago and I’m happy with the results. 
    It has virtually eliminated the creep from the regulator. Before the modification I was getting 10+ bar creep over a day without use. 
    One thing to add. 
    The 11mm spanner  needs to be narrow to fit under the gauge. 
    Otherwise I had no issues. 
    I found some time to shoot the gun today. I didn’t do a whole shot sting but checked speed of a few pellets. 
    On setting B getting around 865fps. Reg pressure just under 120bar. 
    It was very calm and I managed this 5 shot group at 100y

    Id like to say this happens all the time. Truth is it’s the best 100y group I’ve ever shot and I hope I can do it again. 
    Thanks again Gijs +1

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    sonny
    Participant
    Member

    WOW!  nice group

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    jking
    Participant
    Member

    Nice group Airsupply, was that with the 25.4’s or Heavies? Definitely restacking the spring washers didn’t hurt that’s for sure.
    jk

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    weatherby
    Participant
    Member

    “AirSupply”Hey Gijs, thanks for taking the time to explain your modification. I did this to my Crown a couple of days ago and I’m happy with the results. 
    It has virtually eliminated the creep from the regulator. Before the modification I was getting 10+ bar creep over a day without use. 
    One thing to add. 
    The 11mm spanner  needs to be narrow to fit under the gauge. 
    Otherwise I had no issues. 
    I found some time to shoot the gun today. I didn’t do a whole shot sting but checked speed of a few pellets. 
    On setting B getting around 865fps. Reg pressure just under 120bar. 
    It was very calm and I managed this 5 shot group at 100y

    Id like to say this happens all the time. Truth is it’s the best 100y group I’ve ever shot and I hope I can do it again. 
    Thanks again Gijs +1

    Sweet lord, that is a nice group Michael!
    Love it that this mod worked for you as well :)  Could be that in the beginning the spring stack needs some minor time to settle, but mine stays rock solid at 150 bar for weeks.
    At least one advantage of having no time to get out and shoot LOL. 


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    RomeoAlfa
    Participant
    Member

    How high are you able to set the regulator the way it comes from the factory before it starts having creeping issues?

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    weatherby
    Participant
    Member

    “RomeoAlfa”How high are you able to set the regulator the way it comes from the factory before it starts having creeping issues?

    In most cases things start to get unpredictible above 150bar.
    With my modification it is possible to adjust it to a higher pressure without creep.
    A little sidenote: as the hammer of the Crown is rather light, it is not very useful to go way beyond 150bar, because the hammer is starting to get difficulties to knock the valve open.


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    AirSupply
    Participant
    Member

    “jking”Nice group Airsupply, was that with the 25.4’s or Heavies? Definitely restacking the spring washers didn’t hurt that’s for sure.
    jk

    
That was the 25.4 pellets Jimmy. On  many occasions I’ve landed 3 or4 pellets almost on top of each other and then had a stray. As you’d expect they are a lot more sensitive to the wind than the Heavies  But you do sense when shooting it if you get the right conditions this could happen. 
     

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