I took an old and decommissioned 3D printer and built a machine out of it that can turn
your old PET bottles into filament for 3D printing. This is the easiest and most consistent
way to make your own 3D printing filament at home. This material not only prints well
but with a trick becomes one of the strongest materials I’ve ever tested! Let’s find
out more. Guten Tag everybody. I’m Stefan and welcome to CNC Kitchen.
This video is sponsored by KiwiCo. Get 50% off your first month by using the link below!
Let’s start with a poll. If you have used a PET bottle in the last two weeks, leave
a like if you live in a world without PET bottles, feel free to leave a dislike! I’ll
share the results in a week. The thing is PET bottles are everywhere. They are a blessing
and a curse at the same time, providing lightweight containers but too often landing in landfills
or even in nature. But did you know that they can be a valuable resource for making 3D printing
filaments? Good 3D printing filament that you can even make at home! Pultrusion is an
amazing process that first cuts a PET bottle into a long strip and then pulls it through
a hot nozzle, making filament that you can use in any 3D printer. This way, you can really
recycle waste into new and useful parts. I finally built my own machine to show you how
easy it is to make one, and have my own supply of PET filament to do some tests and show
you that this is an underrated material!
So the most straightforward machines that you can find online are simply an old 3D printer
hotend screwed on a piece of wood through which a simple motor assembly draws the plastic
strip. On these machines, you usually first manually cut the bottle into a strip, wind
that onto a spool, and then load this spool into the PET-pulling machine.
Almost two years ago, I already did a strength test video on Bottle PET filament, which I
linked below. For that video, Joshua Tailor also known as JRT3D, who is one of the driving
forces in promoting PET pulling sent me the samples. He designed a variety of machines
for that process, and one of them is his MK5 Kit, where you salvage the parts of an old
Ender 3 and use them to build a compact Pultrusion machine. Why the Ender-3? Because it’s probably
the most popular beginner printer there was in the last year and many might still have
one that’s not working or that they don’t use anymore!
The files for the build can be found on Printables. I printed most of the parts from simple PLA,
only the hotend mount, which can get a bit, well hotter, as well as the gears were printed
from PETG. Since I had to print a complete enclosure for the electronics, it took me
almost 1½ spools of material and two days of continuous printing on my X1s, the Prusa
MK4, and the Snapmaker J1S.
With all the parts at hand, let’s get the old Ender-3 and take it apart for the pieces
we need for the build. The main things we need are the hotend that I removed initially.
Then it was time to salvage the 24V power supply which is totally oversized because
our filament maker only has one small heater and a single stepper motor. The frame of the
recreator is built from z-axis aluminum extrusions that I removed next. Then I unscrewed the
LCD which we still need to control the machine as well as the control board. It wasn’t
necessary to disassemble everything to the last bolt, but if you want to reuse as much
as possible, you can still take the rest of the machine apart. While sorting the pieces
I also found out why the LCD didn’t work anymore because somehow the cable got pitched,
which I quickly repaired. In the end, these were the parts that were necessary to build
the Recreator, plus a bunch of screws.
I first started building the bottle cutter, which slices the container into a strip. This
is a separate project that needs to be downloaded and printed. Joshua's design uses pennies
to protect the part from wear. Since I’m in Germany, I don’t have any pennies, but
due to the community around the Pultrusion machines, there are several different variants,
and one is sized for cent coins, that I printed. This design uses two bearings that ride on
each other to cut or better shear the bottle. It uses the bearings found in the rollers
of the Ender 3. Their edges are unfortunately, or rather by design rounded, so I used a belt
sander to grind one face of each bearing down until the edge was sharp. I screwed everything
together with the grinded-down faces pointing toward each other, forming the cutter. The
lead screw is used to later hold the bottle in place while cutting.
Then I continued with modifying the hotend. In it, the plastic strip will get soft and
reshaped to become a filament. The stock 3D printer nozzle is 0.4 mm in diameter, yet
the filament we want to create is 1.75 mm. So, I used a 1.7 mm drill bit to enlarge the
orifice and used a piece of filament as a gauge to see if I reached the proper diameter.
The heatsink also needs to be modified because you want to have a smooth transition between
the big strip to the thin filament. Since I forgot to get these stepless drillbits,
I went with a 60° countersink that did the job as well. Re-assembly is interesting because
you leave out the heartbreak that is usually between the heater block and the heatsink.
This is by design so that a longer section is warm helping to uniformly soften the plastic
strip. Joshua tries to reuse as many parts as possible from the old Ender 3, so the modified
hotend is mounted on the old x-axis carriage and even the sheet metal cover is installed
to not burn yourself as well as hold the fan to cool the heatsink. All of this gets screwed
onto the PETG mount we’ll install later on the Recreator.
So, as always, I didn’t properly read the assembly manual, which to my defense, might
need some rework. Well, turns out that the parts you salvage from the Ender-3 are not
totally sufficient to build a Recreator. Very early in the building process, I realized
that the 40 M4x8 and the 40 T-nuts are something I would have had to order and there are also
some other screws you should make sure that you have at home. Just keep that in mind when
you see some screws missing. I added them later. The extrusions are held together by
the handles onto which I mounted the power supply. Then, I installed the control board
on the carrier and added it to the frame. Then I screwed the AC socket into the case
and added and installed the screen on the other side. I connected the AC side to the
PSU and the 24V to the mainboard. After this, it was time to route the bunch cables for
the hotend, the two fans and the stepper motor down to the board and plug them in. Then I
mounted the hotend assembly and the cooling fan to the rails.
For the winder, you mount the stepper motor on the bracket and slide on the gear. The
reduction stage is quite interesting because Josh uses a leftover roller as a bearing block
that’s pressed into the mount. This is then mounted to the rail, as well as the other
side of the spool holder. The final component I added was the bottle cutter, and after adding
the enclosure parts on the bottom, the Recreator3D was ready to go! So let’s get some bottles
and make filament!
Last Sunday, we did a family trip down to Lake Constance because we recently had quite
heavy rain, which usually results in a ton of PET bottles being washed to the shore.
I really enjoy taking my daughter with me on trips like this because, for her, it’s
a treasure hunt for trash that we can now finally recycle ourselfs. She is currently
at the age where she wants to know why things are like they are and how things work like
they work. I want to excite and teach her about nature and technology so that one day,
she might come up with ideas that we don’t need to pick up trash in nature anymore. And
this is also the reason why we have been subscribers to KiwiCo, who are sponsoring this part of
the video, ever since she was a year old. They deliver a crate every month filled with
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Let’s start to prepare a PET bottle to make filament out of it. In Germany, we have a
very effective 25-cent deposit system on PET bottles, which is great because this results
in 98.5% of bottles getting returned and potentially recycled. So, making filament from these bottles
might not really be economical, at least here. Yet, there are exceptions to the system. We
have very hard water where I live, so we buy these 5-liter canisters to make our coffee.
They are big and without deposit, so they are a great contestant for making filament!
We first have to clean the bottle because everything that’s on or in it will end up
in our filament. Mine only contained water, so I don’t need to worry about the inside,
yet if you want to recycle your old Coke bottles you need to rinse them thoroughly. Some years
ago I collected even more bottles at Lake Constance but they were sometimes so dirty
that it was almost impossible to clean them. So keep that in mind when looking for resources.
We also need to remove the label. I usually use a heat gun on low to warm up the glue
which makes removing the label without paper residue way easier. The leftover glue needs
to be removed with a solvent. I used Acetone, but Limonene or special sticker remover might
work even better. I tried to make sure to remove everything because the sticky mess
will not only end up in your filament and therefore, your 3D printer but can also clog
up your filament maker. I then had to remove the beading on the bottle, which manufacturers
not only add for aesthetic reasons but also for stiffness. I made sure the bottle was
properly closed and then rotated it over my hot air gun. This first results in pressure
being built up on the inside, which helps push out the creases. Then, I specifically
rotated the bottle at one location to soften the plastic and, with the internal pressure,
smoothed it. I did this until the container was round and without any wrinkles. Then,
I cut the bottom of the bottle off. In hindsight, I should have used scissors for that because
those box cutters are probably the second most dangerous tool in the shop after the
table saw. Next, I cut a starter strip to thread through the cutter. A weight is placed
on top of the bottle to ensure it doesn’t wander out to the cutter. I cut the beginning
of the stip by hand and cut off the first uneven section. Then I used scissors to cut
a very thin section that I could thread through the hotend. Next, it was time to turn the
Recreator on. There is no special firmware required, and the only strange thing you’ll
see is a negative temperature for the bed because we didn’t connect the bed thermistor.
I set the hotend temperature to 210°C and waited.
Once the target was reached, I used some pliers to start the first bit of filament, and trust
me, pulling the plastic strip through the nozzle felt very satisfying! I finally threaded
the first bit of filament through the spool and tensioned it by hand. Josh prepared a
print file that you simply start, and that will turn the stepper motor for a while. And
then it was time to wait and watch the bottle getting sliced, the strip of plastic being
pulled through the nozzle, and the perfectly round filament exiting the orifice and being
wound on the spool. Pultrusion isn’t a fast process. This big bottle took a good two hours
to convert to filament. Yet, even though it’s satisfying to watch, you, of course, can always
just let it run in the background. Once it was finished, I cut the filament after the
nozzle and tried to ensure it didn’t poke out my eye. In the end, I removed the spool
and hand-wound the filament onto a small sample spool. I wanted to look at this process objectively,
so I, of course had to check the yield. The initial weight of the plastic bottle was 80
g, and the amount of filament I could make was around 31 g, which is a yield of 39% and
therefore not fantastic. Unfortunately, especially the top part of the bottle with the threads
weighs quite a bit and, of course, can’t be formed into filament. This yield will be
higher or lower, depending on the bottle that you use, and bigger containers usually will
result in a better yield.
The filament that I made is very interesting. Some might think that we melt the plastic
strip and extrude new filament. This is not what’s happening. The 210°C used on the
nozzle is below the melting point of PET, so we only make it soft. If we check how the
strip looks like after it goes into the hotend, it’s more obvious what’s happening. The
Recreator folds the strip and essentially creates a hollow tube of material. The drilled
nozzle makes sure that a consistent outer diameter is achieved, yet the inside of the
filament will always stay a bit hollow.
And this brings us to printing. PET bottle filament can be printed on any machine that’s
able to go to 250-260°C on the nozzle. The way we compensate that the filament is hollow
is by increasing the flow value in the slicer. For the materials I made, 130% worked quite
well! I printed on PRUSAs Silk PEI sheet heated to 80°C and didn’t have a lot of problems
with adhesion. I had the impression that PET doesn’t like to be printed fast, so I also
decreased the maximum flow to 4 mm³/s. That’s also one of the reasons why we primarily see
the Glycol modified PET-G used in filaments because it flows way better. Other than that,
the bottle PET prints remarkably well and easily. PET Pulling is not a downcycling process.
Using the PET bottle filament, you can’t only print your favorite vase, but it’s
also very well suited for practical parts, like this solar drain clip right here.
I wanted to demonstrate this by comparing the strength of this material against four
other common 3D printing materials: Polycarbonate, ASA, PETG, and PLA. The 5th, opaque white
sample is something special, which I already teased right in the beginning. This is also
PET, but this sample has been annealed, which changes its crystal structure and, for example,
also significantly improves thermal resistance. In order to find out what it does to strength,
I printed three samples of every material and tested them in my DIY universal testing
machine. ASAs tensile strength was the lowest with 43 MPa but it yielded a bit before it
broke. Next came the PETG sample with 45 MPa failure stress on average. PLA was able to
bear 51 MPa. Our as-printed bottle PET came next, failing at 53 MPa on average. Prusa
PC Blend came second place with 59 MPa and something I wouldn’t have expected, but
the annealed and crystallized PET was by far the strongest bearing 72 MPa on average before
failing. Honestly impressive! If you’re interested in a full material test of bottle
PET vs annealed bottle PET, let me know in the comments.
In the end, this simply shows how valuable of a 3D printing material PET is. At least
here in Germany, Pulltrusion is more a hobby than really something where you can save money
and I don’t even want to talk about the hassle working with different material properties
from bottles of different manufacturers and the unknown fumes a material not specifically
made for 3D printing could emit. Yet, where I see the most potential is honestly regions
on earth that don’t have the money and the simple access to 3D printing materials as
we have and where PET bottles are a waste and even a pest. Even though my setup with
the Recreator looks fancy, in the end, you only need a hot piece of metal with a hole
through which you can pull a strip of plastic. This gives you a resource to print parts for
building tools, repairing stuff, education or even printing prosthetics. I seriously
hope this finds more adoption all over the world because it is a way to recycle waste
and adopt 3D printing even in the last corner of the world because PET bottles, fortunately
and unfortunately, are everywhere. There is already a significantly community around PET
pulling with different designs and upgrades, so if you want to get involved, check the
links below! But what are your thoughts on Pultrusion? Did this video motivate you to
try it out yourself finally, or do you think it’s a tremendous waste of time? Leave your
thoughts down in the comments!