Rotation_distance clarification

General Discussion
1

According to https://www.klipper3d.org/Rotation_Distance.html

rotation_distance = <previous_rotation_distance> * <actual_extrude_distance> / <requested_extrude_distance>

which translates to

rotational_distance_A / rotational_distance_B = extrude_distance_B / extrude_distance_A

which makes rotational distance disproportional to extrude distance. I would expect them to be proportional, i.e.

rotational_distance_A / rotational_distance_B = extrude_distance_A / extrude_distance_B

…meaning the higher rotational distance the longer the extruded filament.

Is this a typo carried from a step per mm equation? Which I imagine is disproportional to extruder distance.

Am I missing something?

2

The formula is correct. A larger rotation_distance will result in less filament being extruded. If your rotation_distance is 20 and you ask the printer to extrude 20, it will send 3200 steps assuming 16 microsteps and a 1.8 degree motor. If you change rotation_distance to 40, the printer will only send 1600 steps because it now believes it only needs to make half a revolution to extrude 20mm.

1 Like
3

I see.

So it basically works as an input in the
step/mm = (360/step_degree) * ustepping / rotation_distance

formula in order to tune the actual step/mm for a motor.

4

I forgot to say thank you.

Thank you, @jakep_82