Voron Adaptive Printing — Pressure Advance, Flow, and Temperature Auto-Calibration

Klipper Calibration Advanced

Getting the perfect print on your Voron requires dialing in Pressure Advance (PA), flow rate, temperature, and retraction. Traditionally this means hours of manual testing — print a tower, measure, adjust, repeat. Klipper's adaptive calibration features automate most of this process. From PA auto-calibration with the built-in tuning tower to filament-specific profiles that adjust on the fly, this guide covers everything you need to set up fully automated print quality optimization for your Voron. Last updated: May 2025.

The Problem with Manual Calibration

Every time you change filament brand, color, or batch, you potentially need to recalibrate pressure advance and flow. A different ABS from a different manufacturer can have significantly different melt flow characteristics. Manual calibration involves:

Printing a PA tower (1-2 hours)
Visual inspection and measurement
Updating printer.cfg
Printing a flow tower (another 1-2 hours)
Repeating for temperature and retraction
Total: 4-8 hours per filament type

With Klipper's adaptive calibration tools, you can reduce this to under 30 minutes per filament — and with the right setup, you can automate the entire process so it happens during the first print of any new filament.

Pressure Advance Auto-Calibration

Klipper v0.11.0 introduced the PRESSURE_ADVANCE_CALIBRATE command, which generates a test pattern and analyzes it to determine the optimal PA value automatically.

Single-Filament PA Calibration

The basic workflow:

# 1. Heat the nozzle to your normal printing temperature
M104 S240
M109 S240

# 2. Run the PA calibration tool
# This prints a series of lines with increasing PA values
PRESSURE_ADVANCE_CALIBRATE

# 3. Examine the printed pattern
# Choose the line that shows the smoothest corner without bulging
# Note the PA value printed next to that line

# 4. Save the result
SAVE_CONFIG

The calibration prints a pattern of lines at the perimeter of a small rectangle. Each line segment uses a different PA value. Inspect the corners — the correct PA value produces crisp corners with no bulging at the start of the line and no gaps at the end.

For a Voron with a standard Rapido or Dragon hotend, typical PA values are:

PLA: 0.020 — 0.040
ABS: 0.035 — 0.060
PETG: 0.040 — 0.070
PA-CF / Nylon: 0.060 — 0.100
TPU: 0.100 — 0.200

These are starting points — your specific hotend, nozzle size, and filament will vary. Always use the calibration tool rather than guessing.

Automatic PA with SAVE_CONFIG

After running PRESSURE_ADVANCE_CALIBRATE, if you're happy with the result, save it with:

SAVE_CONFIG
# OR save to a specific section
SAVE_CONFIG VARIABLE=pressure_advance VALUE=0.045 SECTION=extruder

This updates your printer.cfg directly. No manual editing needed.

Multi-Filament PA Profiles

For Vorons with toolchangers (StealthChanger, TapChanger, or similar), you can set PA per tool:

[extruder]
pressure_advance: 0.045  # Default for ABS

[extruder1]
pressure_advance: 0.030  # Different for PLA in tool 2

[extruder2]
pressure_advance: 0.080  # For flexible filament in tool 3

For single-extruder printers, use filament-specific G-code commands in your slicer:

# In OrcaSlicer filament settings → Start G-code:
SET_PRESSURE_ADVANCE ADVANCE=0.045  # For this specific filament

This overrides the printer.cfg value during the print, so each filament profile carries its own PA value.

Flow Rate Calibration (Extrusion Multiplier)

Klipper doesn't have a built-in flow calibration command, but you can use a combination of G-code routines and post-print measurement to automate it. The key is measuring the extrusion volume per millimeter of filament.

Method 1: Single-Wall Flow Calibration

This is the traditional method, automated with macros:

[gcode_macro FLOW_CALIBRATE]
gcode:
    # Prints a single-wall cube for flow measurement
    # Measures wall thickness with calipers to determine flow
    M104 S{params.TEMP|default(240)}
    M109 S{params.TEMP|default(240)}
    G28
    G1 Z5 F3000
    
    # Draw a 20x20mm single-wall square, 10 layers tall
    M117 Printing flow test cube...
    G1 X10 Y10 F6000
    G1 Z0.2 F300
    G91 ; Relative mode
    G1 X20 Y0 Z0.2 E10 F300  ; Wall 1
    G1 X0 Y20 Z0.2 E10        ; Wall 2
    G1 X-20 Y0 Z0.2 E10       ; Wall 3
    G1 X0 Y-20 Z0.2 E10       ; Wall 4
    ; Repeat for 10 layers...
    G90
    M117 Measure wall thickness with calipers

Measure the wall thickness of the printed cube. The expected wall should be 2x nozzle width (0.8mm for a 0.4mm nozzle). Calculate the correction:

New flow = Current flow * (Expected thickness / Measured thickness)
Example: New flow = 1.0 * (0.80 / 0.76) = 1.053

Method 2: Extrusion Volume Verification

A more precise method:

[gcode_macro EXTRUDE_VERIFY]
gcode:
    # Mark filament at 120mm from extruder entry
    # Then extrude 100mm and measure actual vs commanded
    M83 ; Relative extruder
    G1 E100 F300 ; Extrude 100mm
    M82 ; Absolute extruder
    M117 Measure distance from mark to extruder entry
    ; If you marked at 120mm and measured 22mm after extrusion:
    ; Actual extrusion = 120 - 22 = 98mm
    ; Correction = 100 / 98 = 1.0204
    ; Apply: M221 S102.04 (flow rate 102.04%)

Automated Flow Calibration via Macros

For fully automated flow calibration, use a macro that measures extruder rotation distance:

[gcode_macro CALIBRATE_EXTRUDER_ROTATION]
gcode:
    # 1. Heat nozzle
    M104 S240
    M109 S240
    
    # 2. Mark filament 100mm above extruder
    M117 Mark filament at 100mm above extruder
    
    # 3. Extrude 50mm at slow speed
    M83
    G1 E50 F60
    M82
    
    # 4. Measure remaining distance from mark
    M117 Measure distance from mark to extruder entry
    
    # 5. Calculate new rotation_distance
    # Commanded: 50mm, Actual: measured difference
    # New rotation_distance = (commanded / actual) * current rotation_distance
    # Update printer.cfg accordingly

Enter your measurement result and the macro can calculate and apply the new value.

Temperature Auto-Tuning

Finding the ideal printing temperature for a new filament typically requires a temperature tower — a multi-level print where each level uses a different temperature. While Klipper doesn't have a built-in temperature tower generator, you can automate temperature changes during a print.

G-Code Temperature Tower

Use a temperature tower STL from resources like Filament Stories or Teaching Tech, then add temperature change G-code at specific Z heights:

; Temperature tower using CHANGE_TOOL command or M104/M109
; At Z=10mm: Set temperature
{if layer_z == 10}M104 S255{endif}
{if layer_z == 20}M104 S250{endif}
{if layer_z == 30}M104 S245{endif}
{if layer_z == 40}M104 S240{endif}
{if layer_z == 50}M104 S235{endif}
{if layer_z == 60}M104 S230{endif}
{if layer_z == 70}M104 S225{endif}

In OrcaSlicer, add these to "After layer change G-code". Better yet, create a Klipper macro that handles the temperature changes for you:

[gcode_macro TEMP_TOWER]
gcode:
    # Usage: TEMP_TOWER BASE=250 STEP=-5 EVERY=10
    {% set BASE_TEMP = params.BASE|default(250) %}
    {% set STEP = params.STEP|default(-5) %}
    {% set EVERY_MM = params.EVERY|default(10) %}
    {% set current_z = printer.toolhead.z_position %}
    {% set step_num = (current_z / EVERY_MM)|int %}
    {% set new_temp = BASE_TEMP + (STEP|int * step_num) %}
    M104 S{new_temp}
    M117 Temp tower: {new_temp}C at Z={current_z}mm

Call this in your slicer's "After layer change G-code":

TEMP_TOWER BASE=250 STEP=-5 EVERY=10

Putting It All Together: Adaptive Print Start Macro

The ultimate setup is a PRINT_START macro that detects which filament is loaded, looks up its pre-calibrated profile, and applies PA, flow, and temperature automatically:

[gcode_macro PRINT_START]
gcode:
    {% set BED_TEMP = params.BED|default(100) %}
    {% set EXTRUDER_TEMP = params.EXTRUDER|default(250) %}
    {% set FILAMENT = params.FILAMENT|default("ABS") %}
    
    # Apply filament-specific calibration
    {% if FILAMENT == "ABS" %}
        SET_PRESSURE_ADVANCE ADVANCE=0.045
        M221 S100  ; Flow 100%
        M117 Profile: ABS (PA=0.045, Flow=100%)
    {% elif FILAMENT == "PLA" %}
        SET_PRESSURE_ADVANCE ADVANCE=0.025
        M221 S102  ; Flow 102%
        M117 Profile: PLA (PA=0.025, Flow=102%)
    {% elif FILAMENT == "PETG" %}
        SET_PRESSURE_ADVANCE ADVANCE=0.055
        M221 S98   ; Flow 98%
        M117 Profile: PETG (PA=0.055, Flow=98%)
    {% elif FILAMENT == "PA_CF" %}
        SET_PRESSURE_ADVANCE ADVANCE=0.085
        M221 S105  ; Flow 105%
        M117 Profile: PA-CF (PA=0.085, Flow=105%)
    {% else %}
        # Unknown filament — use defaults
        M117 WARNING: No profile for {FILAMENT}, using defaults
    {% endif %}
    
    # Heat bed and nozzle
    M140 S{BED_TEMP}
    M104 S{EXTRUDER_TEMP}
    
    # Home and level
    G28
    QUAD_GANTRY_LEVEL
    G28 Z
    
    # Optionally run PA calibration for unknown filaments
    {% if params.CALIBRATE|default("no") == "yes" %}
        PRESSURE_ADVANCE_CALIBRATE
    {% endif %}
    
    # Bed mesh
    BED_MESH_CALIBRATE ADAPTIVE=1
    
    # Heat soak
    M190 S{BED_TEMP}
    M109 S{EXTRUDER_TEMP}
    
    # Purge
    G92 E0
    G1 X10 Y10 Z0.3 F3000
    G1 X100 Y10 E20 F300
    G92 E0

In your slicer, call it with the filament type:

PRINT_START BED=100 EXTRUDER=245 FILAMENT=ABS

Per-Filament Profile System

Store profiles as a save variable in Klipper:

[save_variables]
filename: ~/printer_data/config/filament_profiles.cfg

[gcode_macro SAVE_FILAMENT_PROFILE]
gcode:
    {% set NAME = params.NAME %}
    {% set PA = params.PA %}
    {% set FLOW = params.FLOW %}
    {% set TEMP = params.TEMP %}
    SAVE_VARIABLE VARIABLE=filament_{NAME}_pa VALUE={PA}
    SAVE_VARIABLE VARIABLE=filament_{NAME}_flow VALUE={FLOW}
    SAVE_VARIABLE VARIABLE=filament_{NAME}_temp VALUE={TEMP}
    M117 Saved profile for {NAME}

[gcode_macro LOAD_FILAMENT_PROFILE]
gcode:
    {% set NAME = params.NAME %}
    {% if printer.save_variables.variables.filament_{NAME}_pa is defined %}
        SET_PRESSURE_ADVANCE ADVANCE={printer.save_variables.variables.filament_{NAME}_pa}
        M221 S{printer.save_variables.variables.filament_{NAME}_flow}
        M104 S{printer.save_variables.variables.filament_{NAME}_temp}
        M117 Loaded profile: {NAME}
    {% else %}
        M117 ERROR: No profile for {NAME}
    {% endif %}

Usage:

SAVE_FILAMENT_PROFILE NAME=ABS_SUNLU PA=0.045 FLOW=100 TEMP=245
LOAD_FILAMENT_PROFILE NAME=ABS_SUNLU

Retraction Calibration

While there's no single Klipper auto-calibration for retraction, you can build a macro that tests different retraction values in a single print:

[gcode_macro RETRACTION_CALIBRATE]
gcode:
    # Prints small tower segments with varying retraction
    {% set BASE_RETRACT = params.BASE|default(0.5) %}
    {% set STEP = params.STEP|default(0.1) %}
    {% set SEGMENTS = params.SEGMENTS|default(10) %}
    {% set current_z = printer.toolhead.z_position %}
    {% set seg = (current_z / 5)|int %}
    {% if seg < SEGMENTS|int %}
        SET_RETRACTION RETRACT_LENGTH={BASE_RETRACT + (seg * STEP|int)}
        M117 Retraction: {BASE_RETRACT + (seg * STEP|int)}mm
    {% endif %}

Use a retraction tower STL and call this in your slicer's layer change G-code. Each 5mm section of the tower tests a different retraction distance.

Voron-Specific Tuning Considerations

Voron printers have specific characteristics that affect adaptive calibration:

Direct drive extruder: Vorons use direct drive (Clockwork, Galileo, Orbiter), which means very short Bowden tubes. This gives better PA response but requires precise PA values — overshoot is more visible than on Bowden setups.
High acceleration: Vorons run at 5,000-20,000 mm/s^2. High acceleration amplifies PA issues. Always calibrate PA at the acceleration you actually print at.

Enclosed chamber: ABS/ASA in an enclosed Voron can drift in temperature over a long print. Consider adding chamber temperature compensation:

[gcode_macro CHAMBER_COMP]
gcode:
    {% set chamber_temp = printer.temperature_sensor_chamber.temperature %}
    {% if chamber_temp > 60 %}
        # Reduce PA by 5% at high chamber temps
        SET_PRESSURE_ADVANCE ADVANCE={printer.configfile.settings.extruder.pressure_advance * 0.95}
    {% endif %}

Long hotend zones: Dragon, Rapido, and other Voron hotends have longer melt zones than typical Creality hotends. This increases the PA value needed but also gives smoother flow curves.

Verification and Fine-Tuning

After running auto-calibration, always verify with a real print. Look for:

Corners: Sharp corners should be crisp with no blobs. Slightly rounded corners indicate too little PA. Blobs at corners indicate too much PA.
First layer: Consistent extrusion width across the first layer indicates correct flow. Too much flow causes elephant's foot; too little causes gaps.
Overhangs: If overhangs curl or string, your temperature may be too high. Drop by 5 degrees and re-test.
Bridging: Sagging bridges indicate too little cooling or too high temperature. PA doesn't affect bridging much, but flow does.

Keep a calibration notebook (or a text file in your printer_data/config directory) with notes for each filament brand and color. Over time, you'll build a library of profiles that make every new filament setup faster.

Troubleshooting

PRESSURE_ADVANCE_CALIBRATE gives inconsistent results: Make sure your nozzle is clean and not partially clogged. Run a cold pull to clean the nozzle before calibrating. Also ensure your extruder rotation_distance is accurately calibrated — PA calibration is sensitive to extruder accuracy.
Flow calibration changes after changing filament color: Even same-brand filaments can vary by 2-5% between colors. White pigments often require slightly higher flow. Black filaments sometimes flow more easily (lower flow needed).
Temperature tower shows no noticeable difference: Your temperature steps may be too small. Use 5-10C steps instead of 3C. For ABS, the usable range is typically 230-260C — test across the full range.
Profile isn't being applied: Check that your slicer's start G-code includes the FILAMENT parameter: PRINT_START BED=100 EXTRUDER=245 FILAMENT=ABS. Verify the variable names match in your macro.
PA value changes over time: Nozzle wear changes the flow characteristics. Replace your nozzle every 3-6 months and re-run calibration. Also check for extruder gear wear.

Example: Complete Adaptive Calibration Workflow

New filament arrives (e.g., eSun ABS+ Gray)

1. Load filament and heat to 245C
2. Run PRESSURE_ADVANCE_CALIBRATE → optimal PA = 0.048
3. Print single-wall cube → wall measures 0.78mm (target 0.80) → flow adjustment = 1.026
4. Print temperature tower from 255C to 225C → best surface finish at 245C
5. Save profile: SAVE_FILAMENT_PROFILE NAME=ESUN_ABS_PLUS_GRAY PA=0.048 FLOW=102.6 TEMP=245
6. In OrcaSlicer, create filament preset with:
   - Start G-code: PRINT_START BED=100 EXTRUDER=245 FILAMENT=ESUN_ABS_PLUS_GRAY
7. First real print — verify and adjust if needed
8. Total time: ~45 minutes (vs 4-6 hours manual)

Next time you print with this filament:
1. Select the filament preset in OrcaSlicer
2. Start the print — profile auto-loads
3. Perfect results every time

With adaptive calibration, you treat each filament as a known quantity with a known profile rather than guessing and hoping for the best. The upfront time investment pays off every time you switch filaments.