Step 13.40 — Set the extruder rotation distance (Ch 14 procedure)¶
Step 40 of 54 · Chapter 13 — Initial startup
(no image — see text)
Gather for this segment — steps 13.40–13.43 (~30 min)
Tools and consumables
- Prusament ASA, dried
- steel rule or caliper
- masking tape
- the laptop with PrusaSlicer 2.9.6
- the
Voron_Design_Cube_v7.stlfile · bin 00-jigs - Prusament ASA, already loaded
- IPA
Already on the bench
- the flex plate, cleaned
Parts:
- Prusament ASA, dried · consumable
- steel rule or caliper · tool
- masking tape · consumable
Do: Load filament. Spool on the holder arm, filament through the PTFE reverse-bowden, tip cut square, fed down the tube to the Clockwork 2 gears. Send G28, then LOAD_FILAMENT TEMP=260; it heats and waits. Wipe the extruded blob off the nozzle.
Check
R reads ≈20 mm, so the extruded amount is within 0.5 % of target: 99.5 to 100.5 mm for a 100 mm request.
What you're looking at
The first print is the last check in this chapter, not the start of tuning. The cube is printed once, here. Step 13.40 loads the first filament and measures rotation_distance — this step owns that measurement; Ch 14 Step 14.7 only re-checks and refines it after the first print. The cube's measurement is Ch 14's and stays there. Keep the cube.
rotation_distance is how far the filament advances for one turn of the extruder motor. Until it is right, every flow number downstream is wrong by the same percentage. The measurement is indirect: the rule reads the remainder, not the amount extruded.
The arithmetic, how to iterate, and the two classic mistakes
actual_extruded = 120 − R
new_rotation_distance = old_rotation_distance × (actual_extruded / 100)
R is what the rule reads, not the amount extruded — forgetting the subtraction is
the classic way to land a rotation distance five times too small. The other one:
always use your current rotation_distance in the formula, never the original.
And remember a higher value means less filament comes out.
Iterate without restarting using
SET_EXTRUDER_ROTATION_DISTANCE EXTRUDER=extruder DISTANCE=<value>, then write the
final number into [extruder] rotation_distance and RESTART. M83 before every
G1 E100 — in absolute mode the move only extrudes 100 mm if E happens to be 0.
Extruding slowly is deliberate: it removes the pressure-related error a fast extrude
introduces. If you would rather not raise max_extrude_only_distance, the Voron
guide's way is to extrude 50 mm twice instead.
Starting value for Clockwork 2 is rotation_distance: 22.6789511 with
gear_ratio: 50:10; expect to land within about ±2 % of that. If you are 5 %+ off,
you have the wrong gear_ratio (50:17 is Clockwork 1), not a calibration
problem.
Measure. Add max_extrude_only_distance: 150 to [extruder] and RESTART — Klipper's default is 50 mm, so a single G1 E100 errors out with "Extrude only move too long". G28, park with G0 X175 Y10 Z50 F6000, heat to 260 °C. Put a piece of tape on the filament at the 120 mm mark, measured from where the filament enters the extruder. Then extrude 100 mm slowly, in relative mode, at 1 mm/s:
M83
G1 E100 F60
Measure from the extruder entrance to the tape again — that reading is the remaining distance R.
Caution
Watch the gears. If the filament is pushed back up the tube, invert [extruder] dir_pin by adding or removing the ! on nhk:PB9, RESTART, and send the macro again. That is the extruder direction test. If the gears do not grab, open the CW2 latch, push the filament past them by hand, close it and repeat.
Tip
write the value you end on into [extruder] rotation_distance, RESTART, and commit. This has to be right before the first print; extrusion error looks exactly like a flow or first-layer problem.
Source: Voron startup wizard § Extruder calibration (e-steps) · Klipper docs § Rotation distance · Klipper docs § SET_EXTRUDER_ROTATION_DISTANCE · Ellis' Print Tuning Guide — extruder calibration · leviathan-printer-rev-d-sbv2.cfg LOAD_FILAMENT