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ProtoCycler

A plastic recycling system for 3D printers...junk goes in, filament comes out! Fully integrated, automated, novel tech & closed loop control

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ProtoCycler is a device meant to recycle waste plastic from either 3D printers (rafting, support, failed prototypes, etc) or post consumer (water bottles, styrofoam, etc) back into 3D printer filament. It has three parts - a grinder, an extruder, and a spooler. It can take in either waste plastic or raw virgin plastic pellets, and dye can be used with either pellets or recycled bits to change the colour.

ProtoCycler is fully integrated with the grinder, extruder, and spooling system all enclosed in a box. It's also fully computer controlled, allowing automation of common plastics like PLA, ABS, PET as well as the ability to hack into the system in two different ways, to completely control the system for experimentation - Either by hacking the hardware with the included software, or hacking into the software itself.

ProtoCycler was started to solve the problem of 3D printing being unsustainable. Between the cost of new filament and the waste generated, we weren't able to fully exploit it's potential! We're firm believers that 3D printing can change the world - but that's only going to happen if it's accessible to everyone, and doesn't contribute to the plastic waste in the world.

We first started ProtoCycler quite a few years ago, right around the time the first extruders (Lymann, Filabot, Filastruder, etc) came to be. We were disappointed by the lack of reliability and performance anyone else offered, and spent over a year trying to perfect that basic design - but no matter what we tried, you had to be a plastics master to get anything usable to come out, and even then the slightest problem would result in a roll of waste, instead of a roll of printable filament! Plus, none of them came with a grinder, or a spooler...so actually converting garbage into filament was a pretty labour intensive process.

We decided to create a machine that would change all of that, a tool that would do literally everything from grind the waste to spread it evenly on the spool of your choosing. It was very important to us that ProtoCycler could be fully automatic and hassle free - because some people just want their tools to work, so they can use them to make other awesome stuff - but it also had to be fully hack-able, so that anyone could modify it to their hearts content.

So how does it work? The grinder section is pretty simple - two really strong toothed wheels bite into the plastic and take little chunks out of it. If you search for shredding videos on youtube, you'll get the idea! The extruder is a lot more complicated. Some key discoveries along the way were that shrinking down industrial scale tech just wouldn't work, and that making an extruder "smart" is incredibly valuable. That's why ProtoCycler features MixFlow technology, to get some of the most consistent extrusion available, as well as a real-time diameter feedback loop, to ensure that nothing ever messes up. In total, ProtoCycler has 5 motors (2 steppers for extruding and pulling, a fan for cooling, a servo for spreading, and a small little motor for spooling) and 3 sensors (1 temp and two diameter) to accomplish it's job reliably. The ground up waste or raw plastic pellets start their journey in the hopper. From there, they're pressurized by the auger/stator assembly. They then leave the auger behind and enter the hot section, where MixFlow mixes and melts them until they're a uniformly goey mess of molten plastic perfection ;). After passing through some filters to make sure you don't get any bad stuff in your filament, the plastic exits the nozzle, where it immediately gets measured by diameter sensor #1. It's then cooled fully, re measured by sensor #2, and finally passes through the puller. The puller adjusts it's speed constantly to ensure the diameter is always perfect, based on the readings of the two diameter sensors and some heavily modified PID algorithms. Last but not least, the filament passes through a servo controlled spreader arm, and onto a spool. All of this happens automatically, and quite quickly - it's easy to get over 5 ft per minute with 1.75mm PLA and, if you can believe it, over 10 ft/min with 1.75mm ABS (cooling is the major limiting factor, and anyone who's 3D printed knows PLA needs to be cooled way more than ABS!). As an added bonus, the energy used to do all of this is only about 60 watts - significantly less than any other extruder, especially when the speed is taken into account.

It's pretty awesome to run ProtoCycler automatically, because you can go off and make stuff while it makes you more filament (which you can use to make even more stuff, while it makes you even more spools to make even more stuff, etc etc). But tinkering and hacking are key to making - after all, this IS Hackaday! - and so anyone can hack into ProtoCycler, even if they've never touched C++...

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  • 1 × ATMega32u4 The brains!
  • 1 × 200 oz in Stepper The brawn!
  • 1 × Tempco Band heater The heater
  • 2 × TI Stepper Drivers Used to power both main motor and puller motor
  • 1 × TSL1401CL For diameter feedback - linear optical array

View all 12 components

  • Grinder Optimization, Intelligent Extrusion returns?

    Dennon Oosterman08/05/2015 at 18:36 0 comments

    We've been working on the grinder tooth profile to create the proper sized chunks with only one pass through the grinder. Depending on the infill percent, shape of the material, etc, the waste can sometimes get shredded into strips instead of ground into smaller bits. While we're optimizing the grinder assembly for longevity, weight, and overall awesomeness we decided it was the perfect time to try and nail down the best tooth profile as well. We're about halfway through right now, as we're now able to grind fully solid stuff without issue (which is something we weren't able to do before), but super thin materials are still creating strips instead of chunks. It seems to be a bit of a trade-off between strength and chip size!

    In other news, as we lost the current feedback system from the DC motor (which augmented, but is not required for, the diameter feedback system) there's no way to tell what force is on the auger, unless the stepper begins stalling, which is obviously not ideal. This means that our Intelligent Extrusion feature has to be implemented a different way. We're testing a few different theories to try and re-gain this capability, and one of the ideas that's looking the most promising is comparing the size of the filament at each sensor. We've noticed through testing that filament that's a little too cool gets stretched out overly aggressively - think of a more parabolic profile - than filament that's the right temperature. And, filament that's too hot gets bubbly and rough. Once the temperature has been settled on, adding an encoder to the stepper would allow us to increase the pressure until it begins to stall, and back off again. While it would be a slightly less elegant "searching" process, the end result would be the same - ProtoCycler can learn about what type of plastic it has without needing you to tell it!

    The very general process we're going to test is to heat the melting section in 10 degree increments until the plastic is extrudeable at a medium speed. Then, the diameter sizes will be compared to find the correct draw down ratio, corresponding to the correct temperature. Finally, the speed will be increased until the stepper begins to stall and / or the diameter becomes inconsistent. At this point, everything will be properly set for that plastic!

  • Motor troubles solved!

    Dennon Oosterman07/08/2015 at 18:37 0 comments

    Had a motor issue with our main auger motor, previously a geared DC motor. It turns out that torque ratings for DC gear motors are for peak load only, and not continuous...and that the continuous load is only about 1/10th of the peak (so much for a 3:1 factor of safety...)

    After much experimentation, we've switched over to a stepper motor for the main auger. This involved changing both the control scheme and physical implementation of the MixFlow melting section so that the stepper's constant speed could be reliably translated into a constant pressure to the plastic. Performance has improved in a number of areas including reliability, tolerance for non-uniform input material, power efficiency at higher speeds, etc. However, intelligent extrusion is not as reliable at this point as there is no pressure feedback...work is being done on the algorithms to try and restore this functionality, but for now testing and design for manufacturing are moving ahead to speed delivery to our Ingiegogo backers.

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Dennon Oosterman wrote 07/16/2015 at 01:14 point

Yes we are! Just need to finish up the "details" section...which I'm doing right now :)

  Are you sure? yes | no

Jasmine Brackett wrote 07/13/2015 at 21:41 point

Hello Dennon & Team, are you going to enter this for the Hackaday Prize and Best Product?

  Are you sure? yes | no

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