Featured Front of AEG cylinder interfering with tappet plate movement?

Discussion in 'Gun Building, Modifications & Repairs' started by gkatev, May 20, 2020 at 6:44 AM.

  1. gkatev

    gkatev New Member

    9
    0
    Heraklion
    Hello,
    I've been doing some work on my AEG's air components, and I noticed that my tappet plate(s) do not seem to complete the full range of motion they were designed to, because they are bumping to the front of the cylinder:

    056.jpg

    I don't know if it's easy to see, but the tappet plate has terminated and is resting on the cylinder instead of on the cylinder header. I'm thinking that it should be able to move back a little more, because at the sector side, the plate has to flex just a bit when the sector clip reaches its "furthest point".

    Honestly, this is not that big a problem, and I'm kind of over-engineering at this point, but I am wondering if it's only my gearbox that has this problem?
    If I take out the cylinder+head I can clearly see that the face of the cylinder head is not flat with the cylinder. Is the slot for the cylinder on the gb too far to the front, or is this pretty much standard?

    I'm thinking of grinding a little bit on the front of the cylinder at the bottom side, to allow for -marginally- smoother motion and feeding.

    315.jpg 056.jpg
     

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  2. cetane

    cetane Well-Known Member

    922
    443
    Markham & Stouffville, Ontario, Canada
    You can trim a notch where the tappet runs. Modify makes some cylinders that are already notched that way..

    [​IMG]
     

  3. gkatev

    gkatev New Member

    9
    0
    Heraklion
    Ah, that's also what I was thinking, just wanted a second opinion.
    Thanks!
     
  4. Guges Mk3

    Guges Mk3 Well-Known Member Supporting Member Lifetime Supporter

    5,842
    3,580
    Minneapolis
    Your shell doesn't have a slot where the cylinder snap fits in?

    Like this?

    [​IMG]
    You can clearly see the cylinder window
     
  5. gkatev

    gkatev New Member

    9
    0
    Heraklion
    Yes it does, and it fits well. As far as I remember it's a VFC box.
     
  6. Guges Mk3

    Guges Mk3 Well-Known Member Supporting Member Lifetime Supporter

    5,842
    3,580
    Minneapolis
    And it over hangs still?

    I think your cylinder head may be an issue if it does. Is that stock or after market?
     
  7. gkatev

    gkatev New Member

    9
    0
    Heraklion
    Well, I've tried a couple cylinder heads, another cylinder and another shell as well, and it seems the same. Do they normally lie flush?

    But still, I don't think the cylinder head affects this. Even if the cylinder head was flat with the cylinder edge, but the cylinder remained in the same position, the tappet plate would not be able to go as far back as it seems it was designed to.

    The way that I judge that the tappet plate should be going back more, is by slowly turning the sector gear, with either the gb closed or open, and observing that the plate has to flex a bit because it can't be dragged back more, as it bumps on the front of the cylinder.
    If I install only the cylinder head, tappet and sector, the movement seems correct.
     
  8. Guges Mk3

    Guges Mk3 Well-Known Member Supporting Member Lifetime Supporter

    5,842
    3,580
    Minneapolis
    They should lie flush or close to it...seldom if ever over.

    Are you working with all stock parts?

    Tappet do normally flex a bit...but that is also dependent on your set-up.
     
  9. gkatev

    gkatev New Member

    9
    0
    Heraklion
    Yea I suppose. Another cylinder head that I found is flush-er. Almost none of the parts is stock :).

    But basically regardless of whether it's flush or not, my "problem" (it's not actually a problem) comes from the placement of the cylinder slots inside the gearbox and the sector-tappet design.
    For reference, the sector is an SHS with the small bearing as sector clip, and the tappet plate is also an SHS (but the same result is observed with some other no-name ones).

    When I say flex I don't exactly mean from the initial impact with the sector clip or from being "violently" dragged along, but rather because it's constrained in the horizontal axis, and so it has to flex/rotate a bit when it's in its fully-retracted position.

    I could post some photos to demonstrate this better

    Either way, I could definitely leave it as is. If I make a small notch on the cylinder like the one in cetane's photo, the effect will be that the nozzle will retract a bit more (how much will depend on the sector/tappet design, and the perhaps on the cylinder head), and the tappet's operation will be just a tad bit smoother, whether that matters or not...
     
  10. Guges Mk3

    Guges Mk3 Well-Known Member Supporting Member Lifetime Supporter

    5,842
    3,580
    Minneapolis
    So the Cylinder should drop into the cylinder window...like below.

    ACM Type

    [​IMG]

    If you cylinder sits in the window and the cylinder head seats on the pegs...well...who is the maker of the mechbox shell?
     
  11. gkatev

    gkatev New Member

    9
    0
    Heraklion
    Yes agreed. When I say the cylinder potentially limits the plate's movement, I mean by <1mm :)

    The shell is a VFC. The "Enhanced Ver.2 Gearbox Shell", I believe.
    IMG_20200520_203115.jpg

    I went ahead and ground away a small notch, and the nozzle does retract more.
    It might not make a difference for a different cylinder head..
    IMG_20200520_203206.jpg IMG_20200520_203147.jpg