Chewing ABS to Make New Filament

Like many other 3D printer owners, I’ve long dreamed of processing post-consumer plastic into new filament for printing. I’ve now taken a couple of steps in that direction.

ABS plastic pelletized with sheet-metal nibbler tool

It should come as no surprise that at times I’ve had a surplus of CRT monitors (surplus of CRTs is redundant, I guess?), many not working. I pulled their PCBs and salvaged their components, put out the metal for recycling, and … cut up the ABS cases into flat chunks and stored them. Did the same with dead inkjet printers people kept giving me — I think they must come in the bottom of cereal boxes.

In tangentially-related news, I’m doing some OpenSCAD design work and a friend is printing the parts for me, as my CupCake has not rehabilitated itself yet. The parts are supposed to friction fit and he has only PLA and I think it’s too brittle for a good fit — if the parts fit at all, they slide too easily. I think they need a little give to slide together, stick in place, and slide apart, so I want to try ABS. I have 3-mm ABS filament but his printer of course uses 1.75-mm filament. I could buy some 1.75-mm ABS filament, but I have all this bulk ABS sitting around …

kitty litter bins of post-consumer ABS plastic

So last night I dug out my bins and color-matched my project to the medium grey ABS and scrubbed it in the kitchen sink with soapy water and let it dry.

washing post-consumer plastic in the kitchen sink

Still hadn’t figured out how I was going to chew it up into pellets. There are plastic shredders, even DIY ones, but they seem frightfully expensive especially once you include the motive power.

I pondered misusing all my different power tools, bearing in mind that my goal was to get pellets somewhere in the size range of rice to peas. ABS dust would probably be fine for re-forming into filament — but much more difficult to capture/collect without impurities like wood dust from other use of the power tools. Tablesaw, sander — dust. Bandsaw, rotary rasp — coarse dust. Drill press — interesting idea but would probably produce spirals that would have to be re-cut; plus any type of bit would be prone to grabbing the plastic and having to clamp it down in each position would take time.

Router table with router set to lowest speed and taking shallow passes — very promising, and very finger-scary. Jointer — definitely the right size chips, and more finger-scary. Lathe — hilarious!

And remembered my hand-operated sheet-metal nibbler.

This morning I produced a good tablespoon of pellets (shown at top) in ten minutes of hand-work as a proof of concept and today I ordered a Filastruder.

I’m still pondering … but I do have a pneumatic nibbler somewhere and I’m thinking about a table design whereby I could feed the plastic to the nibbler. That should be pretty safe, as the nibbler’s up/down action won’t be nearly as prone to grabbing the workpiece and sucking in my fingers.

Although I am going to want some red ABS for this project …

Leave a Reply