Reprap gear ratio

X axis 8t
Y axis 8t
Z axis 8t -> 20t gear ration 20/8=2.5
extruder 11t -> 39t

Nema17 stepping motor  1.8 deg/step    360/1.8=200 step/rotation

http://richrap.blogspot.tw/2012/01/slic3r-is-nicer-part-1-settings-and.html

In most firmwares like Sprinter or Marlin you will find lines in the Configuration.h file that look like this –

//// Calibration variables

// X, Y, Z, E steps per unit – Metric Prusa Mendel with Wade extruder:
float axis_steps_per_unit[] = {80, 80, 3200/1.25,700};

X,Y are 80 step/mm  80X1.8=144deg

Z are 3200step/mm Pitch 1.25 mm M8 screw ,so 3200/1.25=2560 step/mm,due to gear ratio 20/8=2.5    2560X2.5=6400step/mm

Extruder 700 step/mm

Stepper motor – RepRap wiring include

All kinds of stepper motor and wiring.

Stepper motor – RepRapWiki.

The wire color of step motor depend on factory

List below two type are most common one.

Normal wiring

Name	Pololu pin	Color
A	2B	Red
B	2A	Blue
C	1A	Green
D	1B	Black

other type wiring

Red: A+         Red

Green:A-      Blue

Yellow:B+    Green

Blue:B-         Black

similar type wireing

Name	Color
A	Red
B	Black
C	Green
D	Yellow

RAMPS 1.4 – RepRapWiki wiring

RepRap Arduino Mega Pololu Shield 1.4

RAMPS 1.4 – RepRapWiki.