Saturday, May 18, 2013

DIY Cat feeder v2.0

Bingo, I just finished my cat feeder v2.0 ! No more cereal dispenser, I built everything myself ! I had the choice between different systems, but i chose an archimedes' screw. I had several prerequisites:

  • An accuracy of 5grs
  • Dispense food in two bowls
  • Easily get feedback

So I chose the Archimedes' screw, but I still had to supply it with dry food. So I get my saw and medium to build the box. I had set a size constraint : do not exceed the formwork of the radiator in the kitchen, or 11cm. In addition, I wanted to hang it on the wall and paint it in the color of the kitchen, in order to make it less visible.

The box is 11cm x 30cm x 32cm, and is made mostly from 8mm and 12mm medium. (It is almost my stock of wood scrap that determined the thickness).

The system is simple : It's a funnel for the dry food fall into the Archimedes' screw. I had some trouble with biscuits blocked in the hole (causing empty distribution). I solved the problem with some dremel sanding to cut the holes. I then have no worry with it.

When the biscuits reach the bottom of the tank, the Archimedes' screw, which is inside a 4cm diameter PVC pipe, moves the dry food to the two holes.

On this intermediate release, you can see the various components i used : an Arduino, a proto-shield, a DS1307 based RTC board, and a relay board with the IKEA screwdriver motor (FIXA 3.6V).
To attach the motor to the wood, i used polymorph. The binding is very strong and stable, I did not notice any vibration at startup. Pretty awesome.

I also improved the interface by adding a LCD screen, and a serial interface to allow modification of parameters (RTC time, number of distributions per day, reset the last fooding date) and dispense a dose, by sending command throught serial link : h to print help, + to increase the daily distributions...

And finally, here is the LCD display when a distribution occurs. It's a HD77480 LCD screen I bought on ebay for 5€. I used the classical 4-bits interface and the LiquidCrystal library available with the Arduino IDE. I create some custom characters to draw a small clock on the second line.
The first line print the current time and the number of distribution per day, the second the remaining time before the distribution.

Here is a test-run of 24 distributions :

All the code is available on my github


  1. Looks like you need a larger receptacle...

  2. Projet super sympa !
    Je pense que le flux de croquettes pourrait être diminué ou contrôler avec un tube en PVC plus proche du dessus de la gamelle !
    En tout cas c'est excellent :)

    1. En fait, j'ai un souci que j'ai remarqué une fois le conteneur vide : un petit bout de plastique polymorph qui faisait l'étanchéité en croquette a sauté. Du coup, les croquettes tombent aussi au milieu (on le voit bien dans la vidéo...) :(

  3. Thanks a lot for the tip about polymorph plastic, I had as you found Sugru but that only takes you half way! Im now waiting for my polymorph plastic order to arrive. Have you got any pictures of the archimedes screw before you mounted it in the tube? Also how did you mold it, did you do it it parts or just shaped it from one big piece of plastic by had in one go? Thanks for sharing your build.

    1. I have picture of the screw, see here :) In this article, I link some interesting documents about polymorph molding.

      I made it with 1mm sheet of polymorph and then use a powerful lighter to meld the sheet and the axis. It was a very long process !

  4. Nice technology used.I like your post.
    Router Mill

  5. I want to use this motor for a project. Do you know the current it consumes?