ReFil

reFil

A machine that makes filament suitable for 3D printers out of normally unrecycled plastic parts such as HDPE from bottle caps, failed prints etc.

Folders

• schematics - All of the schematics made with KiCAD. Including the gerber files, kicad files (schematic, netlist, pcb, etc.)
• src - The source code running on the arduino nano (arduino/C/AVR ASM)
• mechanics - mechanical parts

Material

The following material is needed for the whole project.

Mechanical parts

The machine is made of lathed aluminium and brass. All the plans will be available in the "mechanical" folder. Including 3D models, plans and specs

Electrical parts

The controller board consists of an arduino nano and a custom board. Using a 24V power supply, a LM7805 regulator is used to drop down the voltage to a usable 5V signal to drive the logic. Since the drop is quite significant and the LM7805 is a simple linear regulator, a decent amount of heat will be produced. This can compromise the functionality of the circuit, so a heat sink has to be appended to it in order to better disipate the heat.

The board will be used to:

1. display the current temperature
2. drive the motor
3. drive the heating element

Temperature sensor

The temperature sensor consists of a PT1000 RTD as part of a voltage divider circuit. The conversion from voltage to temperature can be made by either: looking up a table, or using a formula.

Once the temperature is known, the arduino uses BCD encoding to controll the CD4543BE 7 segment display driver, which displays the temperature.

Motor driver

The motor is a E192.24.246 Micromotors brushed DC thing. It has a 1:246 gearbox that allows it to move things with a high torque (at the expense of a lower rate of rotation. But we don't care about that)

It is using the 24V from the barrel jack and is toggled using a SRD-05VDC-SL-C relay from SONGLE industries.

Heating element

The heating element is a simple nichrome wire that is also toggled with a relay on the 24V power line.