Old indian trick for setting bevel/pinion mesh:

Discussion in 'Gun Building, Modifications & Repairs' started by Automobilie, Jun 6, 2019.

  1. Automobilie

    Automobilie Active Member

    A good mesh between the pinion and bevel provides a quiet gun with minimal squeal (Provided the tooth profiles match).


    I started doing this awhile ago as part of my shimming routine in order to get the pinion/bevel mesh as good as I could realistically get.

    The steps go as follows:
    1. Cut a little window in the top shell so you can see the edge of the bevel gear.
    2. Shim the gun, I generally start with the spur and get it as low as possible to provide as much room for adjustment as possible.
    3. Close up the gun and test fire, adjusting the motor height until tightening just starts to add some high pitched noise back in, then back off 1/4-1/2 turn where the gearbox is the most quiet.
    4. Check the mesh, if the edges mesh, it's about as good as it'll get, though if the gearbox is still noisy you can try moving the bevel up and down and see if it helps; bear in mind some gears just don't mesh with each other well and you'll need to play musical gears.

    In the above photo, the bevel is a little on the low side and may need a 0.1mm raise. However, if the gun is quiet, the mesh is likely fine.

    5. If the pinion is not flush, either raise the bevel so the pinion can set further in or lower the bevel so the pinion sits further out.


    On V.2 guns, I have an extra M4 grip I cut and use to provide a window. In the above photo, the bevel is a little too low and could go up a 0.1mm shim.


    That's all there really is to it. Hope this helps!
  2. Hyperslow556

    Hyperslow556 Active Member

    However, once you put the GB in the receiver and connect the grip to the GB and receiver and slide the motor in place, you will find the motor is lower than what you set it as the receiver is holding the grip to a lower point.

    As far as I know, tuning motor height involves sticking half the shell in the receiver with bevel, then adjusting grip screw till motor has proper mating. For yeas I've been doing this by ear, after eyeballing the half-shell in receiver, motor to bevel alignment.

    This looks like a good method, but I wouldn't tune the height without the GB being in the receiver.
    kazuchan likes this.

  3. Automobilie

    Automobilie Active Member

    This isn't so much for setting the motor height (you'll being using a different grip than you test one when done) as much as it's for setting a good bevel height so that you can adjust by sound. If the bevel height is off, you can still adjust by sound; a quiet point will still be there, but it won't be "the right point".
    -Spitfire- and Hyperslow556 like this.
  4. kazuchan

    kazuchan Member

    on earth
    look like it will suitable more for ver3 gearbox xD.
    Hyperslow556 likes this.