3D Printed Skittles Sorting Machine

This is a custom designed 3D printed skittles sorting machine that sorts skittles by color into bins.

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I started working on this project because I thought it would be a fun project as it has some unique challenges, and it gave me the chance to make heavy use of my newly acquired 3d printer. I wanted to build a compact machine that would sort skittles accurately and quickly. I thought of the idea to use rotating discs to move the skittles to separate bins because it allowed me to make a more compact design. Here is the video of it in action:

You may notice that there are some skittles that don't get sorted into the bins. Those are calibration skittles that are used to calibrate the sensor every time it starts up. You can actually sort different flavors of skittles by replacing the calibration skittles with whatever flavor you want to sort.

  • 1 × Arduino Uno
  • 1 × ZITRADES Color Sensor Module (w/ TCS3200)
  • 2 × HY860D Photo Interrupters
  • 3 × DC Motors with gearboxes These are from the MAKE: IT ROBOTICS GEAR MOTORS KIT
  • 1 × LED

View all 7 components

  • The Color Sensor

    Nathan Peterson09/07/2015 at 03:31 6 comments

    I ignorantly bought the cheapest TCS3200 color sensing module that was being sold on amazon at the time. The TCS3200 chip itself is good, but I wouldn't recommend this board that I used mainly related to the on-board LEDs. They are not pointed correctly, there is no mechanism for blocking light from the LEDs directly onto the sensor, and they do not distribute light evenly on close objects. I mostly solved one of the problems by printing a shield to block the light from directly hitting the sensor. Ideally I would have added a diffuser to help with the other two issues, but I have not gotten around to that.

    Anyway, here is color sensor:

    There was another problem as well in that the surface of the skittles are very shiny and irregular, so they end up producing a lot of glare. I figured out how to get around this issue by placing polarizing filters on both the LED light source as well as over the color sensor itself (at a 90 degree angle relative to the other filter). The idea is that any polarized light will remain polarized if it is just being reflected off of the surface as glare and will get filtered out by the second filter, whereas the rest of the (non-glare) light will depolarize and will not be filtered out.

    Here I'm glueing the filter over the LEDs with hot glue:

    LEDs lit up with filter:

    Here is what a skittle looks like without a filter:

    Here is the same skittle with a filter:

    Here I'm gluing the filter on the part that goes over the sensor:

  • The Motors

    Nathan Peterson09/07/2015 at 01:23 0 comments

    The DC motors came from a robotics kit that I bought at RadioShack:

    Powered by the Adafruit Motor Shield v2:

    Here are the incremental encoder rings that provide position feedback for the discs. They are alternating slots that are read by photo interrupters. After the initialization sequence, this is sufficient information for the microcontroller to tell what positions the top and bottom discs are in.

View all 2 project logs

  • 1
    Step 1

    I don't really have time to create step by step instructions right now, but hopefully you can figure out most of it by looking at the 3d model, source code, and blog entries. I'm also available to answer questions if anyone wants to attempt the build. I'd love to see someone try it!

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Enjoy this project?



arya.camba wrote 11/27/2016 at 20:39 point

Hi! I want to do a sorting machine as you for my school projet but I'm wondering which sensor I should use ? I thought about taking the same as you before seeing this post, but regarding on your experience I'm not sure if I should take it... Do you know something which can work the same way ? I found this: ADA1334 but I wanted your advice first :)

Thank you !

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Nathan Peterson wrote 05/06/2016 at 16:49 point

Hi Nora. I would love to see someone attempt a build and I would be happy to help out and answer any questions if you want to attempt it :) I'm not gonna lie though. The build is a bit difficult, but that shouldn't stop you if you have the determination to do it! These parts have tight tolerances, so you may need to either sand them a bit to get them to fit together, or worse case modify the design depending on your printer. There is also a bunch of soldering involved, and you might not be able to find the exact electronic parts that I used, which means that you might need to modify the design slightly to fit whatever parts you end up purchasing, so you will most likely need to learn how to use tinkercad (which, honestly is not all that hard), but the other thing is that you will probably need to know how to debug the individual sensors and motors to make sure they are connected correctly and functioning properly.

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Nora Jaapari wrote 05/06/2016 at 15:44 point

Hello Nathan, I am not an expert in Arduino nor in 3D printing. However i am fascinated by this idea and interested to attempt the build. May i ask the difficulty level of this project? In your opinion, is it easy or moderate?

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Nathan Peterson wrote 03/08/2016 at 18:43 point

3d files can be downloaded from the tinkercad website that I have linked to on this page. Let me know how the build goes!

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Mithilesh Domala wrote 02/17/2016 at 07:04 point

Hey Nathan, awesome project. I'm interested in building this at my place. Can you share the 3d files so that I can print the separate blocks and assemble them? Thanks.

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MicroPrototype & Design wrote 09/08/2015 at 16:06 point

The world is now a safer place ;-)

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Nathan Peterson wrote 09/07/2015 at 03:52 point

Good to know.  Technically this machine will sort of work with M&Ms, but not as well because M&Ms are a bit smaller and get jammed easier.  Also M&Ms have 6 colors, and this Machine is only designed to sort 5.

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Luke Beno wrote 09/07/2015 at 02:22 point

Awesome, you know color sorted M&M's are really popular for wedding favors and they are pretty expensive, just need an army of these machines.  

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