Animatronic Rat

Step 4 Servos

Now comes mounting the servos. I didn't use store bought mounting hardware and just used some scrap basewood. Its crude but it works. I mounted the mouth servo on the upper U channel so it will move with the upper body and can open the mouth at the same time. I attached the servo linkage as shown and mounted the servo using a scrap of wood.

The body servo is mounted to the lower body L channel and connected to the bottom of the upper body U channel with a music wire connecting rod and linkage connector. The forward and back travel does not need to be extreme. You only need it to help you aim up and down about 45 degrees, if that much. The servo travel was extended by adding a cut down popsicle stick to the servo arm.

To rotate the rat side to side the servo is mounted in the bottom box. An R/C steering horn is attached to the rod or bolt that passes through the top of the box and linked to the servo. If you don't have something similar you can cut a control arm out of a piece of metal and jam two nuts on both sides. On the servo end I added a popsicle stick and metal strip to it to increase the servo arm travel. They are connected together with music wire. You only get 45 degrees of travel side to side, that's the limit of the servo travel. That means you can't squirt someone directly to the side of the prop but if you arrange your rat so people can't go behind it or directly to the side then it's not a problem. You could probably come up with improvements to let it rotate in a greater arc.

I mounted the water bottle, pump, rotate servo, battery pack, and receiver in the bottom with a on off switch. Everything is battery operated so the prop can be put anywhere in the yard without having to attach a power cord. For longer run times a wall wart would be better.