Reusing The Plastic
January 09, 2008 12:11AM
After a part is produced and considered no longer useful, is there a way to heat it back into a thread using a small hole and some guiding loops or is the properties of the plastic changed after the initial heating. if its possible, could call it the 'darwin companion' smiling smiley

idea i have so far is a hopper like object (similar in paint ball guns) to toss in the broken apart plastic pieces. A nozzle with the size of the thread desired, the hopper internally heated to melt the plastic and fans or some sort of colling system to cool it back into a solid thread.
Re: Reusing The Plastic
January 09, 2008 03:03AM
A longer term goal is to have the RepRap be able to use granules or shredded household plastics directly so no need for a filament (thread) this would allow reuse of any plastic that can be extruded.

CAPA and as far as I know any other thermoplastic can be recycled/ reused


Ian
[www.bitsfrombytes.com]
Re: Reusing The Plastic
January 09, 2008 09:04AM
Ah never though about using the plastic already in the house. I figured the plastic RepRap used was special for some reason or another. Hm, I think I'll experiment with it and let you guys know how it turns out in a while, still building a reprap myself.
Re: Reusing The Plastic
January 09, 2008 10:22AM
One of the plastics we've been working with, HDPE, is the same stuff that milk jugs and grocery bags are made of. I worked out that I accumulate 1.5lb (700g) of grocery bags each year. That's nearly enough to build another RepRap.

I can just imagine what'd happen if someone came up with an easy way to use grocery bags as feedstock. The local grocery store has a big bin at the front door where people can deposit their used bags. I wonder if they'd mind people making withdrawals. :-)
Re: Reusing The Plastic
January 09, 2008 10:35PM
lol good question. good luck on finding a way to melt em down smiling smiley
Re: Reusing The Plastic
January 10, 2008 08:46AM
I managed to do a small quantity in the oven at 350F. Probably not practical for larger volumes, though.
Re: Reusing The Plastic
January 10, 2008 11:00AM
Maybe it should have a small blender type attachment, cut up the plastic into shavings so when it gets to the melter, less heat is needed.
Re: Reusing The Plastic
January 10, 2008 01:35PM
There's some info on a possible granule extruder here: [reprap.org]

Might work with shredded plastic as well. Feeding plastic bags into it might be interesting.
Re: Reusing The Plastic
January 10, 2008 03:18PM
wow great link grinning smiley managed to overlook it completely. hm but how would the plastic bag one work now? maybe a tube with a plunger on top that slowly pushed the bag to the bottom to be melted?
Re: Reusing The Plastic
January 10, 2008 03:38PM
How about using a couple sets of small rollers to feed a plastic bag directly into the extruder head near the bottom of the drive screw? The last set of rollers could preheat the plastic film a bit. I understand that a strand is what is currently being fed into some extruders, a twisted plastic bag makes a pretty ok piece of rope. Would be heck-a neat to be able to recycle bags directly into parts.


The Guy
Re: Reusing The Plastic
January 10, 2008 03:40PM
wow nice idea O_o 2 thumbs up
Re: Reusing The Plastic
January 12, 2008 04:21PM
You better hurry, there is a rather strange debate going on right now among the enviromental ocultists (i.e. public media) on putting a ban on the plastic bags for enviromental reasons. There is a ban in some 3d world countries since plastic bags seems to clog up the suers. They of course refuse to realise that the real problem is a total lack of waste management :-(
Re: Reusing The Plastic
January 12, 2008 04:26PM
well if plastic bags get banned at least water bottles seem to be in abundance x_x (tap water kinda guy). i look forward to the day i can use my brother's coke bottle to create things to harass him winking smiley
Re: Reusing The Plastic
January 12, 2008 05:12PM
Transparent bottles are generally poly(ethylene terephthalate) (PET). I don't know if anybody has tried it for FDM, its melting point (260C) is a bit too high for the current extruder.

Milk bottles are a good source of HDPE in the UK.


[www.hydraraptor.blogspot.com]
Re: Reusing The Plastic
January 12, 2008 09:16PM
oh i didn't know that about transparent bottles. I'll make a note to look for HDPE from now on smiling smiley
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