Sep 9, 2015 | By Alec

The link between food and 3D printing is becoming increasingly evident with the advent of food 3D printers, but did you know that there’s more than one way to combine the two? While we never thought we needed it, one Hackaday user has created the ultimate machine for all those picky Skittle eaters out there. Called the 3D printed Skittle Sorting Machine, it has been designed by Nathan Peterson with the express purpose of dividing each Skittle based on color. Do you enjoy one particular Skittle flavor? Do you avoid one like the plague? If so, this is the machine for you.

Remarkably, Nathan Peterson himself (going by the Hackaday handle MrPrezident) claims to not be such a picky Skittle eater. Instead, he claims he was simply looking for a new and fun challenge. ‘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, MrPrezident claims over at Hackaday. ‘I wanted to build a compact machine that would sort skittles accurately and quickly.’

But as you can imagine, there is a lot more to this than a few simple 3D printed parts attached to a little motor. For one, how you efficiently separate Skittles? MrPrezident decided on a remarkably clever design, of a series of rotating discs that move the candy to separate containers. ‘[This] allowed me to make a more compact design,’ he says. And as you can see in the clip below, this actually works quite well.

But the real question is obviously about how to distinguish between the various colors. Well, the designer settled on a remarkably simple color sensor system. The entire build essentially revolves around a TCS3200 programmable color sensor, hooked up to an Arduino. This is capable of identifying different colors, though not very well. Once identified, it gets dropped into a rotating sorter that spins around until reaching the pre-programmed container for this color. This disk is powered by three DC motors, as well as a couple of other sensors capable of detecting when a Skittle has been dropped in the right position.

But as you can imagine, this was not without its problems during design. Especially the color sensor wasn’t everything it was promised to be. ‘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,’ he says on Hackaday. ‘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.’

This problem was almost completely solved by adding an additional 3D printed ‘shield’, that blocks 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,’ he adds.

A further problem was the surface glare on the shiny Skittles, which was solved by placing polarizing filters on the LEDs and on the sensor. ‘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,’ he explains. And as you’ve seen for yourself, this works quite well. The Skittles that are not dropped in containers are the calibration Skittles, which enable the machine to recalibrate itself.

But the best news is yet to come: you can recreate this fantastic machine yourself. Everything necessary, including schematics, source code and 3D printable files can be downloaded at the project page on Hackaday here. But before you try it, here’s one word of warning: this machine doesn’t quite work on M&Ms yet. ‘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,’ the designer revealed. ‘Also M&Ms have six colours, and this Machine is only designed to sort five.’ Perhaps a follow-up project is required?



Posted in 3D Printing Applications



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