This is a treat feeder I designed to feed my dog a Dentastix treat after every meal. After designing and building it, I realized I made this thing waaaaay more complicated and $expensive$ than it needed to be! So yes there’re simpler ways (I intend to make REV2 later on which will be fully printable) but I stuck with my initial idea till the end just to finish it.

Disclamier: This project is NOT FOR BEGINNERS as it is ONLY for an individual who is comfortable with electronics, programming, and machine shop tools. (Also there is one part that is made of stainless steel sheet metal which requires a laser or skilled band saw cutter. I’ve included a printable template so that you can print it out and cut/drill the profile and holes. See PDF for more details. If there are a lot of request (10+) for a non sheet metal base, I will consider redesigning a printable one and posting it.)

Inspiration:
I got tired of constantly having to remember/get up in the middle of dinner to give him a Dentastick after he finishes eating. Being a machine designer by trade I decided to automate this task so he can become more self reliant.

How it Works:
Your Dog places it’s paw on the “Paw” lever which turns ON the machine, then the machine decides if a treat will be dispensed or not and turns OFF the machine (to conserve battery). It keeps track of the “next treat time” and “treats left in the tube before rotation” by storing these values in the EEPROM on the Arduino so they remain in memory even after the machine turns OFF (main reason I used an Arduino). The machine is programmed to only dispense a (half) treat every 8 hours and resets this value every time a treat is dispensed.

Loading the Machine:
You load the machine with an entire bag of Dentastix (Toy dog type). Since I only give him one a day, I break them in half and load each tube with 4 total halves.

2. Purchase all of the components on the list.

3. Download and print all 3D parts.
+ I included gcode files just in case you wanted to start right away. They were created with CURA @ .1mm layer height

4. Cut clear poly the tubes into (12 X 6 inch long tubes)
+ Also cut a 3 inch long tube then in that tube cut a slit .82 inch from top half way though the tube then make another slit (again half way through) 1.75 inch down from the first one. I used a band saw with a blade thickness of .03″

5. Download and make sheet metal base per drawing. (Like I stated earlier if I get enough people (10+) requesting a printable base I will redesign and post.)

1. Tack weld an M5 hex nut to a piece of .02″ sheet metal (see weld nut assembly PDF for more info) I would suggest using an M5 X 35mm hex bolt to help hold it in place and help keep it square while the nut is being tack welded. You will also reuse this M5 hex bolt to drive the gate assembly back and forth. (FYI have a grinder handy as you may have to grind off some threads to make it fit)

5. Assemble 3D printed parts and other mechanical parts
+ 2 X M6X20mm hex bolts with M6 nylock nuts for the paw paddle
+ 2 X M5X20mm flathead screws with M5 nylock nuts to attach the paddle to the base
+ 8 X M4X12mm flathead screws with M4 nylock nuts to attach lazy suzan
+ 14 X M3X12mm flathead screws with M3 nylock nuts to attach , paw switch, paw switch base attachment, battery holder and base skirt. (see materials list for McMaster Pt No.)
+ 15 X M3X8mm button head screws to attach micro switches, arduino to battery holder, relay to battery holder, and side motor cover (you’ll need M3 nylock nuts for motor cover) (McMaster pt no; 91239A113).
+ 1 X M3X8mm socket head set screw
+ 1 X 1/4″ diameter dowel pin 1″ long (could probably print one)
+ [Yes I was dumb to use all different sizes of fasteners but I was lazy and didn’t feel like changing them after all was said and done] Dont Hate!!!!

6. Connect all electronic parts (per diagram)
+ The micro switches need to be wired with a 10k pull up resistor like in this diagram : http://www.me.umn.edu/courses/me2011/arduino/technotes/microswitch/
7. Download sketch to the Arduino
8. Enjoy!