28-BYJ48 Motor and 3D Pen Tip Extruder

Custom extruder made with a 3D Pen hotend and a 28-BYJ48 motor.

Spanish documentation:
https://drive.google.com/file/d/0B-ibO1cgI-iFM2lHTGJUdngtLTQ/view


Marlin configuration

\#define PID_MAX 16
\#define DEFAULT_Kp 2.10
\#define DEFAULT_Ki 0.16
\#define DEFAULT_Kd 7.08
\#define EXTRUDE_MINTEMP 160
\#define DEFAULT_AXIS_STEPS_PER_UNIT {160,160,8000,2250}

Pololu
Microsteps: 32
Vref: 0.2 V