(and probably less expensive) servo. Sometimes low tech is
the way to go!
Tilting the head was accomplished by attaching a 9”
piece of channel to the nod servo into which the second
HS-425BB servo was installed. One end of a 6” rod was
affixed to the servo horn, while the other end was
connected to a 7” piece of flat aluminum. The center of this
piece was mounted on a swivel joint which allows the head
plate to tilt right and left (Figure 14). A second hub mount
with a bolt that ran in a slot in the wood plate was
attached to the channel to provide additional stability.
The assembly went quickly, and in no time I had a
working mechanism ready for the mounting plate to which
the mask will ultimately be attached (Figure 15). The shape
of the mounting plate was first laid out on a foam board
where alterations were simple to do. Once I was happy
with it, I then transferred it to a 1/4” wood piece.
Additional bulk was added to provide support for the
mask by gluing foam scraps to the plate. The foam is easy
to carve to the desired shapes necessary to fully support the
mask. I’ll also add some foam to the top of the shoulder
plate to give it the proper shape. The final finishing touch
for the mechanism will be the addition of a beige woman’s
stocking to be placed on the bottom of it to cover the
visible portion of the mechanism and to act as the neck.
The mechanism to control the jaw was built using a
Hitec HS-225BB mini servo. This servo has more torque than
the Hitec HS-425BB in a smaller package. I added a
mounting plate to a hinge to which a fitted wood piece
42 SERVO 08.2015
Figure 15. Completed three-axis mechanism.
Figure 16. Mini servo to drive the jaw plate.