New features:

  • Integrated cutter with adjustable height
  • New thermocontroller (no special hacks needed)
  • Upgraded motor joint (secured with screw)


No more calculating PET bottle strip width, you can adjust its withs during the filament making. Easy temperature setting, you can rise temperature up and down during the process. You will be able to adjust desired temperature by your actuall needs without any difficulties. Easy build, since we can use a new thermocontroller, we dont need no diode, thermistor, w1009, no external thermometer, no mounts for external sensor.

Conversion from PETamentor MK1?

PETamentor MK1

Yes, its possible in the easy way. You dont need to buy too much new parts (thermocontroller, two microswitches and small dc motor for cutter. Most of the 3d printed parts are still the same. For adding a cutter you have to make two holes for the screws thru the plathorm on the right place. My First MK2 build is on the original MK1 platform. There is the same 12V (7RPM) DC motor with gearbox, because it is the best solution for the puller. The advantage of this DC motor (versus stepper motors) is no heating on the shaft, so your PLA printed motor joint (spool holder) will last much much longer. The power supply unit (PSU) I recommending is 5A+. The heater is about 40W on output, but htere is some consumption on DC motor too. So 5A is my recommended minimum.

The PET bottle cutter

The first idea comes after long frustration with cutting PET bottles into a strips to make some nice filament for my 3D printer. I was too happy with PETamentor, that I forgot the basic thing. It tooks some time when your first builds comes up to a live and you starting to asking me about some bottle cutter. The original one was a totall disaster and it was braking the progress of easy and quick production of my own filament. The worst obsticle was in the bottom of the cutter (nearly under the knife blade). PET bottles are tight and sharp and it can damage any PLA or PETG base under it. As you can see, my idea needs a long time to tweak something useful. This is picture of the very first mechanical solution. The problem was in the resolution of the gear. I had to make 30 spins with my hand to make some visible change on the blade height, So I decide to integrate a small 12V (300RPM) DC motor to achieve some strenght of the system and good resolution to make small height changes. The parts for the cutter are few (for buying) a small DC motor and two simple microswitches to make an easy circuit for changing spinning direction of the blade. And few hours of 3d printing.

Parts list:

Power supply 12V 5A or 10A

w1209 thermo controller diagram

This is heart of the Petamentor project. W1209 is designed for temperature control up to 110 ° C. That’s not much, so we have to change the behavior of the module using diode 5408 on the input.

12V (7RPM) DC motor

The motor is built into the holder and drives the spool for winding the finished pet filament. This 12V DC motor has its own gearbox (it is not necessary to print the gearbox). This means very high torque without any additional gear system.

PWM Regulator 12V 5A

Screws for cutter assembly, puller assembly and spool assembly. The screw is 10mm long – metric M3 type. You can choose the screw head as you like.

Thermocontroller (only 12V – up to 500°C – k-type)

thermocontroller pet filament

Simple wiring, simple remoting temperature. No hacks, no struggle. Be careful on params. You need 12V one with working temperature up to 500C!




12V N20 (300RPM)

Geared 12V (300RPM) DC motor for cutter. This part is moving cutter blade up and down with worm gear 3D printed gear system. The 300 RPM is good speed/torque foe easy, and slow moving the blade up and down.




Microswitch (2PCS)




diy pet filament heatblock

The heat block is the part heated by the heating element (12V 40W). When choosing, it is important to know that the larger the block, the slower it cools with less temperature fluctuations.

Heater 12V (40W)

Ceramic Heater 12V (40W)

Ceramic heater 12V (40W) is a component that is inserted into the heat block and ensures heating of the nozzle. It is a cheap and simple component.

Color Switch (230V)



M3 Screws (10mm)



Nozzle (must drill DIY)



WIring Diagram

There is a complete diagram. This nice and simple scheme is created by Steeve Pechot, THANK YOU STEEVE!♥

petamentor2 wiring diagram