How I Made a Robot Chef

Hey world! I tried making a guacamole robot and ended up with a chef robot. Here's what happened:

**None of the links are affiliated

• 2 Stepper motor driver DRV884
• 2 stepper motors
• 2 stepper motor mounting brackets
• 2 of these kits which include the threaded rods, nuts, and couplers
• Any wood cutting board
• 2 worm-drive Clamps
• A bowl
• Any wood scraps / plywood
• A large cleaver
• Any knife
• 222650 DC Motor - which is a Suburban RV Furnace Motor (I got a used one)
• 1 DC motor driver
• 1” x 3” x 6” Oak board for arm (or any wood but it needs to be a hard wood)
• 2 worm-drive Clamps
• Quick Disconnect Kit
• Actobotics Hardware Pack A (if you choose to get all the Servo City stuff)
• 1.5” x 1.5” Pattern Plate
• Zinc Plated Steel Wheel Axle
• 0.75” Hub Spacer
• U-Channel (7 Hole, 6” Length)
• 2 3” U-Channel, 3-Hole, 3 inch length
• 2 1/2” Thrust Bearing
• 4 0.5” Clamping Hub
• 0.5 x 6” Stainless Steel Precision Shafting
• Servo Plate
• Waterproof Servo
• Servo Horn
• 6-32 Ball Linkage
• 6-32 Threaded Rod
• Phillips Flat head Screws #6 Size 3/4” long
• Dremel Workstation
• Carbide burr bits
• Cutting Oil
• A Raspberry Pi 4
• 1” female stacking header
• Unicorn Hat HD

The best way to get started is by copying your own old work. This mechanism is basically my old Automated French Press but horizontal. This is to sweep all the ingredients across a cutting board onto a bowl at the end.

First I used a jigsaw to cut a hole through the cutting board to fit a bowl, then I screwed worm-drive clams to the edges to hold a bowl (see images).

Then I mounted the stepper motors to the cutting board with brackets and added the threaded rods to the steppers with the couplers.

I used a 1” x 10” wood plank to drive the cleaver with the nuts. I drilled two holes through the cleaver and secured it to it. Then I just made two little wooden stands to hold the rods level to the stepper motors.

I went to my favorite local electronics shop EPO (not sponsored) and bought a used suburban RV Furnace Motor for $30 bucks! Then I met up with my Friendgineer™ Ian to brainstorm the chopping mechanism, give him a follow he is an incredible maker and engineer =) We had a couple calls where we brainstormed the project, I sent him the specs of my motor, and he sent me fancy drawings of the project for me to follow.

The drawings are attached here and honestly they are very straightforward to follow, if you have any questions please comment below!

To make the knife swivel, I got the Servo City stuff and put together. I placed the servo plate on top of one of the u-channels and secured it in place. Then I slid the shafting through the middle hole, then slid one thrust bearing on the top (top of the servo plate) and one clamp to secure it. I slid the other u-channel to the end of the shafting and secured both u-channels with the clamps. The knife will be secured to that second u-channel. I fastened the servo to the plate and then screwed the servo horn to it. I cut the threaded rod to 1” length and screwed two linkages on each end of it. Then I screwed the linkage to the servo horn on one side and the top clamp.

Hopefully the images are more helpful than my description.

To mount the knives I need to make holes through them, I tried a lot of things for a long time and what worked for me was using a Dremel with the Dremel Workstation, Carbide burr bits, and cutting oil.

I paused every few seconds to check the temperature of the bit and if it was warm to the touch I put it in water to cool down. I put a drop of cutting oil on the knife. God speed.

The Raspberry Pi was the brains of all the mechanisms. I used the tall header to be able to solder straight to the Pi's pins and also add the Unicorn Hat on top of it.

I programmed a state machine to make guacamole:

1. At start the Unicorn Hat shows "G 0”
2. The Hat shows which ingredient I should place on the board
3. The Hat shows a countdown “3”, “2”, “1”
4. The chopping mechanism is activated
5. The Hat shows the next ingredient I should place on the board
6. The Hat shows a countdown “3”, “2”, “1”
7. The chopping mechanism is activated
8. Show next ingredient, until done with ingredients
9. Show “D O N E” when all guacamole ingredients are done.

The code is here

Then when I didn't want to do guac anymore I just made it so it chopped until killed and then activated the sweeping script.

My favorite part was playing with the Unicorn Hat because I got to draw all of the ingredients and animate them with pngs. I drew a rainbow cat just for fun =)

Let me know here in the comments if I you need any clarifications, ok byeeeeee!!

Estefannie