Simple clarification on Ultimaker2 extruder gear

[Gregwar]

Hello,

The following line:

#define DEFAULT_AXIS_STEPS_PER_UNIT   {80.0,80.0,200,282}  // default steps per unit for ultimaker2

Imply that there is 282 steps per mm on the extruder gear, right?
It is a 1.8° stepper motor with 1/16 microstepping, still right?

Which means that there is 3200 steps (200*16) in a full revolution. So:

3200 / 282 = 2 * pi * r

Where r is the radius of the drive gear. Thus:

r = 3200 / (282 * 2 * pi)
r = 1.8 mm

Where am I wrong? I guess the drive gear is really bigger than that

[rafaellsi]

Full revolution = 3200* (extruder gear ratio)

[Gregwar]

Ok, but "extruder gear ratio" is actually the perimeter of the gear, right?
(So 2_pi_r where r is the radius of the gear)

[whosawhatsis]

@rafaellsi gear ration is 1:1.

@Gregwar The extruder uses a .9° stepper, 400 steps/revolution, so your first number should be 6400.

[Gregwar]

Ok @whosawhatsis I didn't know it was .9° steppers!
So this mean that the gear diameter in the code is 7.2mm, it seems right, thanks for the clarification