How to Make a DIY Filament Maker from Discarded PET Bottles: A Step-by-Step Guide
A short video of the process
In this article, I will walk you through how I made a DIY Filament Maker Homemade. Just Like my article about DIY 3D printer, tries to see if we can make a homemade filament maker with minimal materials and tools.
Nowadays, 3D printing is getting very popular not just within the manufacturing industry, but with hobbyists and maker communities as well. As we all know, sometimes prints fail mid-print. And we will discard that failed print. Even though this project won’t be about recycling failed 3d Prints, that’s a topic that I would like to address with another project in the future. In this project, we are going to try to make our filament using discarded PET bottles.
There are some benefits to making homemade filament. First of all, it’s very cheap. Per day, we at least come into contact with a PET bottle at least once. Many of them are discarded ones. If we can stop those discarded bottles from going into the trash heap and recycle them it would make a huge environmental impact.
When we make our own filament we can make the appearance of the material and properties to fit our needs. For example, if we want green-colored filament, we just need to find green-colored pet bottles. This would also be a very educational project for anyone, making your filament will teach you a lot about materials, the extrusion process, and quality control. And you won’t have to rely on suppliers to get filament, you won’t have to wait for filament to get delivered and you will always have filament on hand.
Note: This project is not finished. There are a lot of improvements I have in mind that need to be implemented. However, this will give you an idea about the process and this is a very simple project. You will be able to try this on your own, with just a few hours invested. We’re currently working on updating this article to bring you the most current information. Stay tuned!
PET bottles into filament
There are a few things that we have to understand before we go to build the filament machine. The first thing is the quality of the filament you’ll make will depend mainly on the prep work. You will have to clean the PET bottles inside and outside well. You will have better quality filament if you source clean new bottles that don’t have scratches and dents.
After you source your bottles, you will have to clean them thoroughly. Remove any stickers, glue, and labels. Most bottles that you find in the wild will have some patterns or will formed into different shapes. We need to turn them into uniform round tubular shapes so we can cut them into strips of consistent width.
The way we are going to do that is by heating them. But, we can’t just point a heat gun at the bottles and expect them to turn into proper tubular shape. We will have to put a little bit of water in the bottle and close the lid. Then heat the bottle slowly. You can use a heat gun or a gas stove to heat the bottles. but in my experience, the gas stove worked well heating the whole bottle instead of just one place.
When we heat the bottles, the water inside the bottle will turn into water vapor(steam). Because we have closed the lid of the bottle, the vapors will stop the bottle from deforming into unusable shapes. The bottle will shrink in size a little bit but that’s fine.
After we heat the bottles and form them, then we will cut them into strips. The width of the strip will depend on the thickness of the plastic strip. Usually, 4-5mm strips work fine. You will have to test this yourself.
We can use different methods to cut the bottles into strips of consistent width. But, the best way I found was to use two bearings. When I say “with two bearings”, it’s only fair that you get confused. With that, I meant we can make a strip cutter at home with two bearings and a few nuts and bolts.
It is very easy to make and it produces plastic strips with consistent width. In contrast, if we used a pair of scissors or a utility knife to cut the bottles into strips, the results would be too inconsistent and not worth the effort. This strip cutter makes it effortless to cut the bottles into strips.
Note: The filament we make with this machine will be hollow inside. The filament we buy is solid inside. What happens if we use this filament without changing printer settings (slicer extrusion multiplier) is that the prints will have under extrusion because the filament is hollow inside. We can remedy this under-extrusion by changing the “Extrusion multiplier” in the slicer software.
The reason for this hollow space inside the filament is that we don’t heat the PET strip to its melting temperature when we make filament this way. We just heat it till it becomes malleable enough to pull that strip through a cone-shaped nozzle to form it into a round filament. If we heat the strip enough for it to melt, the process will be much more complicated than this. At least for now doing it this way is the best.
I’ve set the extrusion multiplier to “1.3” = (130%) in my slicer settings. Normally if you’re using filament that you bought from a supplier or a store, by default this value will be “1” = (100%). But since I am using filament I extruded myself, I have to change this value to “1.3” to account for the less material in the filament.
Materials and Tools Needed
You will only need a few things and tools for this project.
Materials
- DC power supply 12V 10A
- 1.75mm nozzle (This is the filament diameter most printers in the market use you can choose a different diameter nozzle if you want filament with a different diameter.)
- DC blower fan
- Microcontroller (I’m using an ESP 8266 but you can use Arduino Nano or Uno)
- A thermistor or a temperature sensor.
- Relay or SSR (Solid State Relay)
- Heating element 12V
Note: You can buy the heating element + thermistor + heating block for very cheap on Ali Express. For around 3 bucks which would save a lot of time if you wanna go with that. I have made the heating block the heater myself so I know how much of a headache it is. It’s not worth it trust me 😂
Tools
- Screwdrivers
- wire strippers
- Base plate (I used wood, but any non-conductive material will be fine)
Building the Homemade Filament Maker
Now let’s get started with the build. First I will give you an overview of how this process and machine works. We are going to cut the pet bottles into strips first, then we are going to feed them through a heated nozzle to change it from a strip into a circular filament which or printer can use. We are going to use the microcontroller to manage the temperature, it will read the temperature using the thermistor and turn the heater on or off.
From my experience, it’s OK if the temperature varies by a couple of Celsius during the process. So the simple heat On heat Off system worked fine. We will use a relay to turn the heater on or off with the signals from the microcontroller. However, it would be better if you could use a Mosfet or an SSR (solid state relay) to turn the heater on and off. It would provide many benefits compared to using a relay. It would eliminate the clicking noise produced by the relay when in operation. And relays are prone to fail because they’re mechanical (contacts welding together after repeated use). SSR would eliminate all these downsides
Above are the basic electronics that you need to make this work. I have a single relay and a 10KNTC thermistor with a 10K resistor for the voltage divider. You can always add a display to show the current temperature and set temperature of the hot end. But this would work well enough to make some filament. You will have to fine-tune the temperature on the first time though.
I didn’t have a thermistor at hand when I was making this, so I had to improvise and use a non-contact IR temperature when making this. Which was totally over the top and made it more complicated than it needed to. It was also hard to get an accurate reading because it was non-contact. I strongly suggest using a thermistor if you’re planning to build this.
In the above image, you can see the different components.
- Old laptop blower fan to cool the filament after it exits the nozzle
- Induction heater circuit
- Contactless IR temperature sensor
- Nozzle and Induction coil
- Aluminum block to cool the filament.
How the machine works
When we turn on the machine, we can set the nozzle temperature. Although it’s very convenient to be able to control the nozzle temperature. I think being able to change the nozzle temperature is not very important. My argument is that all the PET bottles start to deform at around the same temperature. I only say this from my personal experience. Although it is very convenient to be able to control the nozzle temperature. We can make the coding part and wiring even simpler if we don’t intend to change the nozzle temperature with a display and a rotary encoder.
After setting the temperature, the relay will close and turn on the heater. When the temperature sensor detects the nozzle temperature reaching the set point, the relay will open and stop the heating element from further heating the nozzle.
after the nozzle reaches the set temperature, we can start pulling the plastic strip through the nozzle. At the moment I haven’t added a motorized pulling mechanism to pull and wind the produced filament into a spool. For now, I’m only using a spool mechanism with a hand crank to pull and wind the filament.
The aluminum block in front of the nozzle has a 1.75mm hole. This aluminum block has two purposes. One is to cool the filament, The other goal is to ensure that any variations in the filament’s diameter remain consistent throughout the entire length, so the filament maintains uniformity and works smoothly with 3D printers without causing issues. Since I’m not using a motorized spooling mechanism to pull the filament through, filament diameter will vary slightly without this aluminum block. since I can’t control the force my arm produces, consistently and accurately.
The images above don’t show the power supply, the relay module, ESP32, and the 7805 voltage regulator which I used to regulate the 12v to 5v to supply the ESP32. these components are fixed on the underside of this machine.
If you’re willing to spend a few bucks, you can buy a hot-end heater block from Ali Express for around 3 bucks. This is the easiest way since it comes with the heating block, the heating element, and the thermistor. All of that for just 3 bucks. All you have to do is add a 1.75mm nozzle, the Arduino Nano, and a relay.
In this prototype version of the
At the moment I don’t have this motorized, so we have to manually pull the filament through the hot end. Even though it’s time-consuming the results have surprised me. I thought the filament thickness would vary a lot considering that I can’t put a constant pulling force on the crank to get the same thickness. But from what I’ve seen it doesn’t affect the filament thickness very much.
I’ve printed some models with the filament that I pulled manually. I was expecting some over and under-extrusion in the printed parts. But they came out relatively good considering how little effort it went to make the whole thing 😂.
We’re currently working on updating this article to bring you the most current information. Stay tuned!