Recycling HDPE plastic containers into filament

I've been researching the process of turning things like milk and detergent bottles into plastic that I could use in my printer. I think the idea of recycling plastic takes on a whole new appeal if people knew they could use the bottles to create free plastic objects. I think that the barrier now lies in the fact that currently you have to shred the plastic in order to recycle it into long lengths of filament. I have an idea that there could be a way to melt a bottle and push the melted plastic straight to the extruder nozzle during printing. I'm not sure if it could work, but I'd like to experiment with this idea more in the near future.

jkelso, you can shred the bottles in a rock tumbler from harbour freight or a hardware store, and then use a granular feed type extruder with your reprap.

Maybe.

(It's not in the wiki, but someone may have done it already on a personal blog.)

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-Sebastien, RepRap.org library gnome.

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Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything!

I'm thinking that you could flatten up to 5 or 10 bottles in the chamber, then use a hand crank to thread the chamber closed so that the plastic pushes through the bottom. I would think that you would only need to heat the bottom area of this chamber. I guess it wouldn't be efficient to feed this straight to the printer but maybe it could be a way to make your own filament without shredding


Edited 1 time(s). Last edit at 09/07/2010 11:37AM by jkelso.

Grains->Filament->Extruder is an extra processing step, compared with
Grains->Extruder.

Also, I think you need a few hundred plastic bottles to have a few pound of thermoplastic. A Personal Recycler may be a blind alley or frustrating process compared to doing stuff through a local filament supply place that can buy a ton of shredded recycled plastic at a time. (I'm not sure.)

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-Sebastien, RepRap.org library gnome.

---

Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything!

In general, I agree that this could be a **HUGE** source of frustration at first but I think we need to find a way to make this work. The Makerbots now have self unloading platforms and I would expect quick resetting to become common with reprap systems soon. That combined with more reliable extruders leads to an ability to print a whole lot more than ever before. Right now the cost of the filament is minimal compared to all the other cost of equipment and time, but as these systems perform better, the biggest cost will be the consumables, specificly the plastic.

You are right, there really isn't much plastic in a milk jug but you can get pretty well all you want by buying it from your local recycler for what they would get paid or being the local recycler. Thats kind of a lifestyle choice. I happen to live next door to the most active local recycling advocate so its not an issue with me.

Additionally, the ability to melt down your own plastic and extrude it will make failed print jobs a lot easier to deal with.

On the side , I would expect that the presence of such a system would put more pressure on the idea of having the print head stationary like in the makerbot, than have it move around like in darwin and mendel. Personally I see strengths in both configurations but I lean towards the stationary printhead idea. Neither are evil. :-)

I'm very interested in the recycling plastic idea. If I could get enough printable plastic cheaply, I could print larger and more things which leads to greater usefulness.

bowden extruder?

Bowden extruder could work, but it would require the entire length of the extruder to be heated to ensure the plastic remains fluid while it travels to the print head...

One way of doing it might be to cut off the necks and bottoms of bottles and slit the resulting cylinder into a continuous strip that can be fed directly to the extruder, instead of double-handling via filament processing. The next problem would be how to change source strips automatically.

Edited 1 time(s). Last edit at 11/25/2010 07:40PM by murrayd.

I am currently working on a project that I have posted on kickstarter. This device called a Filabot will allow for just that. I have already made some HDPE plastic filament of of some milk jugs and a detergent bottle.

Check the Site out here.

I started researching 3d printers because I have an unlimited supply of HDPE available from local ice cream shops in the form of ice cream buckets with 1mm thick walls. It would be relatively easy to get about 150 m of continuous 1mm by 1mm square filament from one of these buckets by setting up a razor blade and fence to push it through (the hardest part would be scraping the paper decal off). Does the filament need to be rounded or sized or could it be used as is?

if you could do a consistant 1x1 square section you might be able to get something working
duno how well it would work once it got to the hotend, as I understand it the round filiment expands as it heats up blocking the hole in the ptfe and stopping backflow.
another problem you're going to have with HDPE is it shrinks a lot as it cools. so it's not easy to print with.

I shredded a few buckets since my last post. It is easier to get a consistent 1x2 cross-section although the equipment I am using at the moment is a bit crude. Is there any reason the extruder intake couldn't be rectangular?