[Ondřej Šraitr] has several videos, including the one you can watch below, about his PETamentor2 — a machine for turning PET bottles into printable filament. You can grab the files on Thingiverse, and there aren’t many parts you have to buy.
The device looks good, and from the videos, it appears to work well. A blade slices the bottle into a strip that feeds what is essentially a hot end that pushes out the filament. The blade is adjustable to set the amount of plastic fed at any given time which is important because you need enough to create a solid piece of filament but not any more than that.
Surprisingly, the bill of materials doesn’t include any sort of microcontroller. There is a PWM speed control module to drive the 7 RPM motor and a temperature controller. Of course, you need a power supply, a heater block and a heater. The nozzle is, oddly enough, a standard 0.4 mm nozzle. You drill it out to 1.5 mm and die swell takes care of getting to the final 1.75 mm size.
It takes about 45 minutes to eat up what looks like a 1-liter bottle. The filament produced looks good in the video. We aren’t sure, but we think that was a roll of solder used as a ballast weight on top of the bottle keeping it moving in a downward direction. Bottles imply wetness, of course, so after producing the filament, it needs to be dried.
This is the second version of the machine and we were a bit surprised that we never saw a video of the filament in use. But it looks like it would work and it isn’t like we haven’t seen this technique used before. In fact, we’ve seen it several times. We can’t remember any that looked as stylish as the PETamentor2, though, and we are interested to hear about anyone’s results with the resulting filament.
*belches* It is just so perfect and well working, but me liver would advice to switch to non-alcoholic beer for making this work. Sadly there is a recovery system in my country (and a few other EU countries) that prevents these shenanigans by putting a small refundable deposit on each bottle.
Same. I would love to try one of these out, but the recycling system in my country also works with a rebate, and it is cheaper to just turn my bottles in for recycling and buy PETG on a spool. I’m not sure which is the more eco-friendly option tho.
What about cutting the strip to be 5 times thinner and feeding strips from 5 bottles to single extruder in parallel? That would yield 5 times longer filament….
My thoughts exactly.
Ok, now you’ve the filament, but what next ? How do you print with PE in a standard 3d printer, without destroying it ? The usual part in the printer are in PTFE, and can’t support the temperature requirmeent of a PE filament, right ?
Not sure, isn’t printing PETG relatively easy? Is it only because of the added glycol?
Not personally tried the bottle through the printer but I understand the temperature requirements to print it to be well within the range of even the cheapest printers, its not some super exotic that needs hugely high hot end heat, listed melting point is 250C, which is low enough it should be fine for any printer.
melting at 230° for me. The size and the velocity help low temp
The nozzle and hotend will be 250c but with a heat break the ptfe tube can be much cooler. Snapmakers dual extruder head claims 60c at the PTFE tube while 250c nozzle.
Considering he uses a modified standard nozzle to make the filament, I’d expect you can use a standard nozzle to print with it.
I thought pretty much everyone switched to all-metal hotends years ago for exactly that reason. I’m guessing it’s been 4 maybe 5 years since I replaced my J-head and I thought I was way later than most people in doing so. I replaced it with some cheap thing off Fleabay that called itself an “all metal J-head” but actually is as far as I can tell, a clone of an E3D V6. I think they go for between $10 and $15 US these days.
I’ve read bad things about these cheap clones. I followed the advice from a Youtube video where a guy the inside of his clone hotend using a drill-bit in a Dremel tool and toothpaste. Mine has worked great! I don’t know if the drilling process was necessary or if it would have worked as well without it.
Before the switch I struggled against warping, printing in ABS because I wanted to make things that could survive inside my car on a hot day. (PLA cannot) Now I do almost everything in PET-G and am still very happy I made that upgrade!
There are known problems using 100 recycled materials. Typically only using 20 percent. One would be carborizing, two brittle parts. Curious how this might work.
The biggest problem of this method is the filament size. One 2L bottle can do around 10 meters of filament, and join 2 pieces is a pain. This method is old, about 7 years, and on all the forum, facebook or youtube, the problem always is do more filament with more than one bottle
Seems this tech is still missing reliable processes for making the flat strips and joining filament lengths. I wonder if joining filament strips would be more reliable, thinking of an angle cutting and fusing fixture like in a movieola.
Er, meant “I wonder if joining *flat strips *(before extruding) would be more reliable.”
Yeah, amazes me no one has come up with a tried and true trusted method to either join the strips or the filament that quicker than the ones that appear effective if you don’t wind your filament to a small diameter roll.
I’ve also wondered about drilling a MIG tip out to 1.7mm. I’ve seen that report by one user for their system and reads like that style tip threads are the same for their MK8 nozzle.
The 1.7mm tips aren’t common in the U.S. from what I’ve seen… though I’m not a welder and search engine are strange at times maybe?
It seems to me like adding a filament sensor so the printer automatically stops and alerts wouldn’t be that bad of a compromise. (maybe a simple beep, maybe a phone alert via Octoprint or similar) It sounds easier than joining filament. But then I haven’t tried this yet.
Since there is probably a bit of filament left after the sensor anyway, it would be cool if the printer could be smart enough to finish the wall it’s working on (if it’s working on a wall) and pause at the infill so as to hide any stop/start marks.That seems like it would take merging the slicer and the firmware though.
Maybe it could be accomplished. What if the slicer added comments to the G-Code indicating what is wall and what is infill. Maybe the comment could include what length of filament the section is expected to take to complete. Then an Octoprint plugin could read that information as well as the filament sensor alert and make some really smart choices about when to stop both minimizing the wasted filament and always stopping in the infill.
Or does all this capability already exist? I have not played with a filament sensor yet.
One option is to use a printer with filament swapping capability or filament runout sensor like the Prusa to run multiple short lengths of filament on a single print. I’ve done this on my Prusa to use up multiple short ends from spools, works fine just requires you to pay a little attention and do the swap in a timely fashion.
Can we be far from an extruder mod that takes the flat strips directly? It seems like a waste to have to melt the plastic twice. Also, there ought to be a simple way to weld strips together to get any length. Something like a heated pair of pliers that just presses them together. Didn’t ancient film editors sometimes use a hot splice that worked like this?
Or, how about a hopper and auger that replaces the extruder altogether, with the auger driven by a stepper motor? Of course, then you have to cut or grind the bottle into proper granules, but it wouldn’t be limited to just PET.
That would be great to see someone try. Experimental data is better than guesses. My guess though it is won’t turn out as well.
I’m thinking forcing it through the extruder hole standardizes the filament diameter. If you printed from the ribbon directly, how stable is the width? Also to consider is different bottles having different material thickness or even different parts of the same bottle.
One might think that the extruder of the printer itself would serve the same purpose. But as you get to bulkier or less bulky regions of ribbon when making round filament maybe it just varies the speed at which the filament comes out while still resulting in the same dimensions. If you vary the speed filament comes out during a print however you get problems since it has to be timed with the movement of the carriage.
OTOH, that reduces the number of times the plastic is melted by one and that will help improve quality.
This was actually already done and featured on hackaday:
https://homofaciens.de/technics-machines-3D-printer-Granule-Extruder-V3_en.htm
Sorry, I should have been more specific. I was responding to the first part of BBJ’s comment, printing directly from ribbon not granules. Printers that print from granules are pretty much the norm already when looking at large format printers. I know I have seen them at Maker Faires printing things like usable chairs and life-size statues. The one that sticks out in my mind had the pump/top of a shop-vac built into the extruder and the vacuum hose extended down into a large barrel full of granules. That was pretty cool.
Of course the extrusion size was big enough it’s output could have probably been used as filament in most of our “normal” printers.
I thought I remembered, back in early rep-rap days someone had tried that at sizes more like what most of us have at home. Maybe that’s your link here? I’m going to go check that out.
I remember reading that the ISS was using a printer that could recycle old prints in space. Don’t remember seeing any detail on how it worked though. Would be interesting to see.