Thread: Discussion Walkera 4F200 3 blade head
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Old Aug 31, 2012, 12:56 AM
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United States, MN, Coon Rapids
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4F200 Modification for Installation of EMAX ES08MD Servos

The EMAX ES08MD servos are an upgrade option for the 4F200 cyclic servos. They perform better than stock and are an all metal gear digital servo. These servos are also a tad more responsive than the prior Futaba S3154 servos I had installed in my 4F200. Not a major difference, although small enough to notice from a non-pro 3D heli pilot like myself.

Here is the original manufacturer's web page for this servo:

They are priced around $12.00 each and can be purchased from the following USA web sites:
But, modification of the 4F200 will be required if you want to upgrade, since these servos are taller in dimension than the stock servos. The rest of this post I have documented the steps I took to get these servos to fit securely into the 4F200 air frame.

DISCLAIMER: This post does not represent the one and only way of doing this. It only represents "a" way of doing it. If you are up-to-the-task of modifying your 4F200 then proceed and only proceed at your own time and cost. I shall not be held liable for any type of loss associated with the modifications described by this post.
  1. Here is why modification is necessary. The ES08MD servos are simply taller than the stock servos.

  2. Tools you will need to get the job done.

  3. Prepare all servos. Use a file to trim away plastic. An unmodified servo is on the right.

  4. Modify elevator servo insert.

    Use dremel cut-off bit to assist with trimming. Most important here is to relocate bottom two holes to a lower position. Use 1/16 inch drill bit to help with relocation.

    Here is how the elevator servo insert looks with the bottom aluminum support re-installed.

    Here is the elevator servo re-installed and fitting nicely.

  5. Here are the two aluminum pieces that need to be modified. These are the pieces that are used to mount the pitch and aileron servos.

  6. Modify the HM-4F200-Z-15 piece.

    Clamp this piece to the work bench and use a file. Grasp the file firmly with two hands, hold it level and steady moving through a consistently firm forward and back motion in order to achieve the best results. It doesn't take much force to file away the soft aluminum, so be careful and take your time.

    The finished HM-4F200-Z-15 piece. Use a 5/64 inch drill bit to enlargen the servo slots. The original is on the left.

    The pitch and aileron servos test fitted into the modified HM-4F200-Z-15 piece.

    The HM-4F200-Z-15 piece re-installed into its original location.

  7. Modify the HM-4F200-Z-16 piece. Use a file to trim this one. Notice the two screws are filed down as well.

  8. Use a 1/16 inch drill bit to help elongate the servo tab mounting holes downward.

  9. Use a 1/16 inch drill bit to help elongate the holes in the fiberglass frame upward. Here also the pitch and aileron servos are test fitted.

  10. Here is how the pitch and aileron servos look re-installed.

  11. Last modifications are the servo horns. I use the inner most hole and use wire cutters to trim off the portion of the servo horn not being used.

The final steps are to mount the servo horns to all servos at 90 degrees as much as possible. Then adjust the servo horn to swash plate linkages. Ensure the swash plate is located in the center of its travel (pitch up and pitch down travel) Ensure the swash plate is level.

Finally go for some test flights and fine tuning of linkages and fine tunning of electronic settings in both transmitter and receiver.

Modification complete.


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