Fx impact valve control knob UK spec

Forums PCP Airguns Fx impact valve control knob UK spec

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    bucketboy
    Participant
    Member

    The uk spec valve control knob is slightly different to the higher power models. Instead of a bump ball it has a  secondary valve return spring.

    The knob is in 4 parts, the cover cap, that limits access to the valve knob control screw, the return spring and main body.


     

    I was having slight consistency issues, the gun would occasionally send pellets at two different speeds. I was sure it was not reg or hammer related and suspected it was something to do with the valve control knob.

    When I got it off the gun, I pushed a dowel into the knob to simulate the valve rod hitting the spring. I could feel the coils of the spring riding over the threads for the adjuster screw inside  the main body. Repeatedly pushing on the spring it would frequently snag up and not return to its full length.

     

    my solution was to make a ptfe sleeve to fit over the spring and a guid to fit inside the spring.


     

    fully assembled, the spring now moves much more smoothly, with no binding or hang ups.
     


     

     

    I have slightly modified the guide shown in the photo to accommodate a small rubber bump bead, hopefully this will give better consistency and ease tuning.

     

    Bb

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    Airgun-hobbyist
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    Member

    Very nice work!

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