PET Bottle Recycling: Waste to 3D Printing Filament

PET Bottles are everywhere, but did you know that you could recycle them into 3D printing filament and this at home! Let me show you how I used the parts of an old Ender-3 to build a filament maker out of it. I also tested the strength of this material, which can even be improved by a trick!

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Chapters:
00:00 Introduction
00:35 PET Bottles
01:37 Pultrusion Machines
02:31 Printing the Parts
03:00 Disassembling the Ender 3
03:44 The Bottle Cutter
04:32 Modifying the Hotend
05:40 Building the Recreator
07:06 Sponsor
09:16 Preparing the Bottle
11:33 Starting the Pultrusion Process
13:55 Printing BottlePET
14:55 Strength Test
16:10 Summary

#3Dprinting #recycling #pultrusion
DISCLAIMER: Part of this video was sponsored by KiwiCo.
FTC Disclaimer: A percentage of sales is made through Affiliate links

[CNCKitchen]

Is Pultrusion a big waste of time of a feasible way to make good filament?

[brezovprut]

Nice video as always Stefan. Just few important notes for fellow makers:
1. Dry your bottles (or bottle strips) in dehydrator for 8hrs on 70C before pultrusion
2. Pump the pressure of the bottle before heat treating surface with schrader tire valve.
2. Check the thickness of the bottle and readjust bearing cutter by using Petamentor2" calculator or manually (thinner the bottle wider the strip)
3. Each bottle brand might need specific pultrusion and printing temperature (eg. some of my bottles even couldn't be purged below 280C)

[davidkint]

Whether it is a waist of time or not, the best part about doing something like this is the excitement it creates to go out and clean up trash. Plastic bottles are everywhere.

[eideticex]

Note for those of us with SAE drill bits. A 1/16th bit will produce a 1.57mm hole on a drill press but chucked into a handheld drill gets much closer to 1.7mm. The test hole I drilled in a scrap piece of steel fits a cutoff of 1.75mm filament snugly.

[dailyscarystories]

im glad you are bringing this to a bigger platform, a lot more people are going to try jt now

[fluxx]

I would very much love to see some more testing of this material. But there may be too much variables to control to do it justice. I went down the rabbit hole and built myself a rig for pet recycling during COVID. I gathered all the info I could and used it to make my own experiments and I consider it to be a great overall material, similar to perg, but seems even better in some aspects. However, I ended up using entirely different set if parameters than yours, with still great results (though I have no hard data to prove it, other than my opinions and observations). To me, it is only a viable option if it can replace my need for commercial filament. This means it must be easy to make in enough quantity when I need it and produce comparable results. It also needs to be cheaper, which comes down to how much time it takes to make as in my country (Serbia), the bottles are everywhere. First, the quality - it's definitely comparable, perhaps only except color. You are a bit more limited there. You can try and color the strips and it somewhat works, but the colors aren't as saturated. Second, the time it takes to make - I used different parameters for pullstrusion and I can get a 2l coke bottle done in 25mins and it yields 15-20g of filament if prepared right. An order of magnitude faster than what you mentioned. I don't know if there are downsides, I didn't measure, but the quality is perceptibly the same as the longer methods. I used 235°C and a fast enough feedrate to land on 25mins for lets say 18g of filament. Even if this is slow for some, the process can be parallelized by having multiple machines running at the same time. But the device has to be cheaper than an old ender 3. Luckily, there are people who managed to bring the cost down to very cheap. Check out Petamentor for example, but there are more. Now we come to the biggest problem - quantity. 20g of filament is simply not enough for a lot of the prints and if it is, you are left with a few grams of unusable filament in the end either way. A solution is to join more filaments together. Joining then reliably is a problem. The biggest one for me, which in the past has made me give up on using recycled material. First - forget about joining strips, they simply can't survive the stress of pulling through the nozzle. Plus, like you mentioned, the process doesn't actually melt the strip, so it won't melt the strips together either. I tried joining strips in multiple ways and never had a successful pull through. I tried 100s of times - melting, mechanically interlocking, chemical solvent based bonding, and combining it all, it doesn't work in a diy environment. Otoh, joining finished filament is deceivingly simple. You take a piece of PTFE tube, melt two ends by flame or heater (I used a soldering iron) and while still molten, you slide on the tube. When it cools, the joint is done. However, the joint is very stiff and brittle and often breaks even if you just try to wind it on a spool. If it kinks before it gets in the extruder - forget it. Relieving the pressure on the joint helps somewhat, by making the bends before and after it to increase mobility. I tried faster and slower cooling, various things, but IMO, this is still the biggest issue and stops you from making a spool of say 200g of filament and just hitting print. I recently stumbled upon a guy that solves it by making a huge diameter spool, which is a genius idea (function3d on yt), he has many different good ideas too. This prevents the filament from bending too much and breaking the joint. Also, fresh off the machine, the filament tends to uncoil and spring back to a big diameter, making spooling it impossible. But not if you have a big enough spool. I will have to try that, as it looks like it's the missing puzzle piece for making the process of making filament viable.

Next - printing. I found that printing at high temperatures enabled faster printing. I had little zero issues of crystalization. I print on 280°c and have great results. I think layer adhesion is great, but have no numbers. I think overall strength is good, but have no numbers.

Other notes: it's prone to moisture absorbtion like petg. Drys easily. Appears to be somewhat self-regulating in terms of density consistency, I had good results on same settings with vastly different strip widths and thicknesses. Once the joint makes it into extruder, it doesn't cause problems. It frequently snaps while entering. Clogs weren't common. Cleaning wasn't too important, except for label adhesive. White spirits/turpentine works good, less toxic than acetone. I blow up bottles with a bicycle pump to 2 bars before treating with hot air gun, that way the bottle doesn't shrink. More than 2 bars risks explosion.


I'd love to see annealing at least, but other tests too!

[_Xantras_]

Little tip if you struggle to remove the POM wheels from the bearings : leave them a few minutes on a 90°C bed, they will easily fall off

[drauc]

I love these recycling-themed videos you do. Praying a cheap and reliable pultrusion machine comes to market soon!

[ronnybergmann]

I had the same thoughts on using PET Bottles here in Germany so I looked out for a different material that is used everywhere and always thrown away. Joghurt and curd cups are abundant and made from polypropylene (PP). PP is a pain to prepare and cut with the bearing cutter but there is a razor cutter somewhere on thingyverse or cults3d that works nicely. My recreator version is not ready to test yet but I made some PP filament in the past and found that PP has some really interesting material properties like environmental and chemical resistance and being dishwasher compatible. Might be interesting to have a look at! Thank you for sparking new interest for turning waste into useable stuff!

[Fejszi]

I’ve built a machine since your previous video about this topic, its a quite nice hobby, but the best thing in my opinion would be desgning a lowcost filament extruder in a sinilar fairly easy to build manner. Then we could use the whole bottle, use the caps of the bottles or even something like a milk jug or containers that pudding comes in. In my country (Hungary) we have a bearly functioning collection strategy with no deposit so I’d love to build an extruder, but the ones alaready in the wild are either really expensive or built from literal scrap

[ldomotorsjason]

Thanks! Insane that you made one. We are keeping support and sponsor Joshua / ReCreator, but we finally decided not to make a kit for it, since it’s much easy to get parts from scraps, and save cost. Great video, thanks for spread recycling sprit! See you soon.

[AdlersAesthetics]

The hollow result makes me want to see if you can stuff other materials into the center before pulling making composites, would that be something you could try?

[IanFiebigwi]

I've been gathering so many different versions of these. But no easy to follow video like this. This is exactly what I was looking for as I've been starting one of these PEt recycle projects!
Thanks!

[Silor]

I would be interested to see a full test round on crystallized PET. Amorphous PET will momentarily become extremely sticky while melting, and that basically stops up any industrial machine melting plastic. For that reason PET pellets are crystallized in special machines that keep them moving while heating them, like a washing machine but with infrared light instead of water. From experience crystallized PET is really similar to PBT but possibly more brittle, usually in manufacturing we try to avoid crystalization afrter remelting by cooling the parts quickly. Slower cooling after remelting results in crystalization - opacity and brittleness

[Cengizhan]

But the Pfand tho 😭😭😭 jk it looks so cool

[Brian-S]

A curious child is a wonderful thing and I couldn't think of someone better to be the teacher. Your daughter is going to be one smart kiddo

[BaldEagleD]

been making pet filament for 1 year now, and for the price of less than 2 euros per kg (electrical bill), it has been great, better thermal resistance, better uv resistance, easy to print. made my own version of a pet pull, even made a tutorial how to build one. the downsides: short pieces of filament, not easy to splice together, not the best looking prints(transparent filament, standard blueish colors, more stringing )

[ethanbunch]

I work in a diesel shop and we get pallets of water bottles in to drink. All of these are tossed in the garbage but the advantage is that they're all the same brand they're all clean and the shop even gave me a recycling bin so that I can use the filament out of it! I pretty much have the perfect setup and although I have doubts about how much time it would take I'm sitting on a potential Gold mine of filament

[williamelewis]

I like your optimism, not a lot of people have that lately.

[cwjwh]

Anything that helps recycle OR gives inspiration to create something better is always a good idea. Danke!