How I made a guac machine

I am Mexican and I eat guacamole everyday, so I made a guacamole machine. Watch video to see why, the build, and the tests :) Continue reading below for tutorial.

 
 


This machine has three main mechanisms: the chopping, the swiveling, and the sweeping.

The sweeping knife

I basically copied my old Automated French Press build and made it horizontal to move a big knife to sweep all the good stuff onto a bowl that I screwed onto the cutting board.

Things I re-used (links are NOT affiliated) :

I cut the cutting board to fit the bowl and mounted it with the worm drive clamps (see image). Then I mounted the stepper motors with the brackets to the opposite side of the cutting board, and then I just added the threaded rods to the steppers with the couplers.

I used the same old wooden stick (1” x 10”) from the french press project 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 stands to hold the rods level to the stepper motors.

Automated French Press github.

The chopping Mechanism

Things I used (links are NOT affiliated)

I tried looking for a linear actuator motor that could stamp a knife onto a board, but after doing some research (5 min Googling) I realized those motors are very expensive. So I went to my favorite local electronics shop EPO (not sponsored - this is my favorite store and I want them to thrive forever) and bought a suburban RV Furnace Motor for $30 bucks!

I also bought some gears. That’s what mechanical engineers use right? Back in the lab I tried sketching and trying to put the gears together, I remembered how I did not take enough physics in college or ANY mechanical engineering classes so I called my Friendgineer™ Ian.

Ian is a mechanical engineer, an electrical engineer, a computer engineer, AND YouTuber. He invents crazy stuff like these skates and this something…. THEN raffles his inventions to support good causes. He is an incredible engineer and friend. Please consider subscribing to his channel =)

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.

 

motor

motor specs

 

Ian’s fancy drawings:

I am not sure what else to say here but good luck!!! hahaha go watch the video.

The swiveling knife

Materials (not affiliate or sponsored, ServoCity please sponsor me hahah)

I needed my knife to also swivel, so after sending my cruddy drawings over to Ian he modified them to be a bit safer.

To 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.

I mounted it to the oak plank with the Phillips screws.

And that’s it! Hopefully the images are more helpful than my description:

The knives

What I used (again, not affiliated):

The easiest way to make holes through the knives for me was with a Dremel press and these bits. 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 also put cutting oil on the knife. That is all I can say about making holes through steel. God speed.

The Electronics and code

What I used (not affiliated):

Code is here.

The Raspberry Pi was the brains of the whole machine. I programmed a state machine which controlled the motors in each mechanism. I used the Unicorn Hat to tell me what the machine was doing:

  1. At start show“G 0”

  2. Show next ingredient drawing

  3. Countdown “3”, “2”, “1”

  4. Show current ingredient

  5. Show next ingredient, until done with ingredients

  6. Show “D O N E”

Playing with the Unicorn Hat was probably my favorite thing because I got to draw all of the ingredients and animate them with pngs. I drew a rainbow cat just for fun.

I used the tall headers to be able to solder wires to the Pi and also stack the Unicorn above that.

Aaaaand I think that’s it!! Let me know here in the comments if I am missing something or if you need any clarifications / help, ok byeeeeee!!

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BuildsEstefannieComment