What is intended is to give it all the naturalness possible as seen in the film, therefore, it is quite a challenge to work with such a small space, which presents certain difficulties.
The first thing to note is that the line of the eyes is not in a horizontal position, they are forming an angle, this presents a difficulty because operating the orbits of both eyes involves independent servos and, consequently, double space. For this reason the eye sockets only have a right-left movement, up-down is discarded for space.
The head incorporates 6 servos inside, with them I try to give it all the expressiveness possible, they are arranged as follows:
- Eye sockets.
- Eyebrow (Frown)
- Upper eyelids
- Lower eyelids
This is a complete picture of the head mechanism:
This is a picture from the bottom:
Holes are provided in the chassis (green part) to facilitate the passage of the servo wiring.
On the outside, a cutout has been made to serve as an Exoskeleton and the external skin has a consistent base to attach to. Below you can see the original image and the cutouts made for mounting.
This piece has been printed without filling and with 1.8mm of layer thickness at 100% although depending on the printer it may be necessary to increase the thickness.
All cutouts have been previously marked in pencil and then cut with a small dremel cutting disc. You have to be very careful in this step since the outer layer is very fragile.
For the interior anchorage a screw is used in the front part (we will see it in the assembly steps) and two lateral ones in the hearths of the ears.
In the lower photo we can see how the sides go, these holes can be marked with a pencil from the inside.
The external part of the head is downloaded from here: https://www.thingiverse.com/thing:4021315