Designing and building an automatic cat feeder

One of the most popular DIY projects you'll find on the Internet is an automatic pet feeder. Although automatic feeders can serve the useful purpose of feeding your pets while you are away, they serve the even more useful purpose of disassociating the pet owner from the pet's perception of human as the dispenser of food. The Pavlovian response of the pet as the owner enters the kitchen is thus transferred to the whirring of a motor as food magically appears in the dish. In this article, I try my hand at creating a dual pet feeder for my two cats.

Concept

One of my requirements was that the food had to be fully enclosed, so the kibble would not be exposed to the air to give off tempting aromas and would be inaccessible to prying paws. I decided to accomplish this by building a small tub that rotated within a larger tub, matching open slots through which the food falls. This design required that the tubs fit fairly snuggly, without touching, so kibble would not be trapped in between.

I used littleBits modules [1] with a Cloud bit to activate servomotors that rotated the inner tub. An IFTTT recipe [2] controlled when the mechanism was activated and followed the cats' usual feeding schedule.

Structure

The most difficult part of the project was designing the structure that holds the food dispensers. Luckily, I own an Alessi Tigrito cat bowl [3] (Figure 1) with an ascending tail, on which I could hang an aluminum Actobotics [4] mounting bracket. Figure 2 shows the bracket with the littleBits servomotors attached. To build the mount, I used the following parts:

• 1x 4.5-inch channel
• 1x 1.5-inch channel
• 1x quad hub mount
• 4x flat channel brackets
• 12x socket head screws

Figure 1: The Alessi Tigrito cat feeder by Miriam Mirri. The tail, which is usually used to pick up the bowls, served as a convenient place to hang the bracket mount for the food tubs.

Figure 2: The feeder mount. The hole in the hub mount at the top fits over the tip of the tail on the feeder. The servo arms are attached to the inside tub in the final design.

Figure 3 shows the mounting bracket with one set of tubs installed.

Figure 3: The mounting bracket with one feeding apparatus attached. The tub with the red lid (left) holds the cat food and sits inside the larger tub (right).

To hold the food and protect it from the external environment, I used a set of nesting food containers. With an X-Acto knife, I cut a small hole in the center of the inner tub (Figure 4). In the outer tub, I cut a rectangle (Figure 5) in which to insert the top of the servomotor, along with two mounting holes for the screws. When the tubs were nested, the servo arm hub poked through the small hole in the inner tub, and the arm was attached (Figure 6).

Figure 4: Inner tub with hub hole.

Figure 5: Outer tub with servo slot and holes for socket head screws.

Figure 6: Nested tubs with servo arm attached.

Each tub had a slot cut into its side. The slot in the outer tub faced down to deliver the food. The slot in the inner tub was offset and only aligned with that in the outer tub when the servomotor was activated. The size of these slots depends on the size of the kibble and the amount to be delivered.