Despite being a readily-available source of useful plastic, massive numbers of disposable bottles go to waste every day. To remedy this problem (or take advantage of this situation, depending on your perspective) [Igor Tylman] created the PETmachine, an extruder to make 3D printer filament from PET plastic bottles.
The design of the extruder is fairly standard for such machines: a knife mounted to the frame slices the bottle into one long strip, which feeds through a heated extruder onto a spool which pulls the plastic strand through the system. This design stands out, though, in its documentation and ease of assembly. The detailed assembly guides, diagrams, and the lack of crimped or soldered connections all make it evident that this was designed to be built in a classroom. The filament produced is of respectable quality: 1.75 mm diameter, usually within a tolerance of 0.05 mm, as long as the extruder’s temperature and the spool’s speed were properly calibrated. However, printing with the filament does require an all-metal hotend capable of 270 ℃, and a dual-drive extruder is recommended.
One issue with the extruder is that each bottle only produces a short strand of filament, which isn’t sufficient for printing larger objects. Thus, [Igor] also created a filament welder and a spooling machine. The welder uses an induction coil to heat up a steel tube, inside of which the ends of the filament sections are pressed together to create a bond. The filament winder, for its part, can wind with adjustable speed and tension, and uses a moving guide to distribute the filament evenly across the spool, avoiding tangles.
If you’re interested in this kind of extruder, we’ve covered a number of similar designs in the past. The variety of filament welders, however, is a bit more limited.
Thanks to [RomanMal] for the tip!
I’ve lost count on how many times I’ve seen one of these bottle filament thingies, but one thing that I’ve always wondered was where people were getting such smooth bottles without any ridges from.
One I saw recently showed the missing step: you fill the bottle with compressed air, and heat it with a heat gun. Smooths it right out.
Huge bottles from beer market
Inflate and heat regular bottles
Or fill the bottle with fermenting homebrew. When the bottle creaks, the ridges are gone (and it’s time for rebottling the brew..).
I love how dry ice bombs creak before they explode.
It’s just a cool noise…Anticipation.
At 12-15€/Kg PETG I won’t even think about using plastic bottles… There’s a 0.25€ deposit for those bottles (which are 100% single-variety recycled for use in new bottles). Plus the label often uses some very sticky glue which 100% stays on the bottle.
I know this is not buy-off-of-amazon-a-day but some things just make no sense in some environments. This is one of them…
Bottle glue can be removed easily using spray bottle filled with acetone/ethanol mixture. Recycling should always be a priority unless otherwise allowed.
In my experience, plastic bottles used as dry ice bombs are returnable for deposit.
But they just glance at the pile and weigh them here.
Not Germany, talk about insane recycle process, attached caps?
I can think of no better thing to recycle a plastic bottle into then an explosive entertainment.
That said, California politicians love bad ideas.
Good thing their too busy dreaming of national office, hence acting sane for the moment.
I will say, you at least get something for the 0.25.
Euro bottles have thicker walls, might be more difficult to cut.
In addition to crazy deposit and ‘must be in like new condition, washed, with cap still attached’ rule.
I should experiment with dry ice bombs in Germany, but rules crazy relatives, always watching and judging.
I just judge them back…
Bet the stronger bottles make them even better.
The stupid attached-cap thing is not for deposit reasons but an EU thing for “we don’t want the caps to litter the environment”…
The deposit machine (Leergutautomat) scans the specially coated barcodes. Those must be readable by the machine. That’s what matters.
Regarding dry ice b*mbs with those bottles: I should try that. There’s even sturdier plastic bottles: 1.5L coke bottles :) They have walls more like >0.5mm thick yay
Welcome explosive pyromaniac!
Just be careful.
Don’t get caught.
Expect a longer delay then you’re expecting.
They creak for a few minutes sometimes, maybe 10.
Warm water speeds things up a lot, but increases chances of blowing up in hands.
Good luck in your future life as a pyromaniac.
Just for reference:
A properly executed dry ice bomb sets off car alarms for about a half block w thin walled American 2 liter bottles.
Exercise appropriate caution.
Try to get the deposit back, the bottles usually split up one side.
There is no deposit here in Ohio. We do have curbside recycling pickup but after all those documentaries about how plastic sent to be recycled often does not get recycled… Well in some environments things DO make sense.
Any ridged bottle can be smoothed
out easily. Just put the cap on tight and carefully start warming it on an electric stove. The air inside will expand as it is heated. Keep turning the bottle as it self irons out the ridges.
What´s the point of melting it once to transform a flat strip into a filament then once again in the extruder ?
Call me when one can just stack empty bottles in a tank and the created strips gets directly melted to the print.
because the strips won’t be cut evenly enough to guarantee a consistent volumetric flow and will not be round like normal filament, far better to extrude it into a consistent size/shape so that the slicer can produce the correct gcode for you.
Aluminum melts as well as plastic. Aluminum is cast into ingots, why not plastic ? Then use an extruder just like Aluminum extrusions.
I think it’s due to air getting trapped inside the molten plastic. You can heat aluminum as much as you want but plastic will burn.
Viscosity. Plastic will decompose before it becomes anywhere near as fluid as molten aluminum.
Every re-melt makes most plastics worse.
Actually all plastics, but some are so much worse.
Nylon take’s it pretty well.
Get the ‘plastic is like metal’ idea out of your head.
There are plastic extruders, tube, pipe, filament etc.
But they are different from metal extruders.
Molten plastic is a compressible liquid.
But that’s the realm of injection molding and real plastic extruding, 3d printing doesn’t get there.
I don’t know what I’d use the output from this device for, but, I wouldn’t want to print with it. I’d probably damage my old cheap printer. :D Usually I cut the tops and bottoms off of 2l soda bottles, use the top as a base for painting minis and other small things, the bottoms as parts trays (paint pallets, whatever), and sandwich the middle section between 2 3D printed parts to make display stands.
Not as good a repurpose as a dry ice bomb.
For the 10 year olds reading…I really should define terms.
Dry Ice ‘thingy’ process.
First, get plastic funnel, cut the output at diameter that just fits into plastic bottle.
Buy 10 pounds/5kg dry ice at grocery store (‘rents sent you to get it ‘for party fog’), store in cooler.
Wear gloves and safety glasses!
At scene of prank:
Hit the dry ice w hammer, breaking into bottle neck size pieces.
Put dry ice pieces into plastic bottle using funnel.
(optional: add some warm water, not recommended for first efforts).
Put lid on tight.
Put someplace where it won’t damage anything you don’t want damaged. (e.g. right under traffic camera, beware the second camera watching.)
Stand well back.
Enjoy creaking, then boom.
Run away laughing.
Don’t do this with glass bottles, you’ll likely only blow the cap off, but you might get lucky.
I should add:
Don’t do this.
This is not legal advice.
I love the re-creator guys, but I’ve always been concerned because I’ve heard from plenty of sources that these bottles have dyes and other chemicals in them (that we probably shouldn’t be drinking from in the first place), but are ten times worse whenever you melt them and evaporate some of it.
Be aware. Loading just the website, even with no scripting allowed,
automatically downloaded an unwanted pdf-file on my computer.
PET is hard to print as it will crystalize when from melting to solid. Such crystalization will cause shrink and warp the print.
I would much rather have an affordable machine that could turn supports, purges and failed prints back into usable filament.
What about this recycling extruder?
https://hackaday.io/project/181165-direct-granules-extruder-fdm-prints-from-powder
When state enforces bottle deposits, they should buy these machines from makers.
For all users of similar projects, here is a simple strip width calculator for you fillament thickness