new_rotation_distance = current_rotation_distance x (actual_extruded / requested_extrude)


Example: If rotation distance is 7.710, you asked for 100mm, and measured 98mm:

new = 7.710 x (98 / 100) = 7.556


Update in `printer.cfg` and restart.

### Step 2: Calibration Print — Single Wall Test

This is the gold standard for flow rate calibration.

**Model:** A hollow cube (no top, no infill) with 1 or 2 walls, 20x20x20mm.

**OrcaSlicer settings:**

- Layer height: 0.20mm (for 0.4mm nozzle)
- Line width: 0.44mm (extrusion width = 110% of nozzle)
- Wall count: 1
- Top layers: 0
- Infill: 0%
- Bottom layers: 3 (just for first layer adhesion)

**Print and measure:**

1. Print the cube
2. Wait for it to cool
3. Measure wall thickness at 4 points on each side (12+ measurements total)
4. Average the measurements

**Formula:**


new_flow = current_flow x (target_width / measured_width)


Example: Target width 0.44mm, measured average 0.47mm:

new_flow = 1.0 x (0.44 / 0.47) = 0.936


### Step 3: Flow Rate Tower

Many slicers include a flow rate calibration tower that varies flow at each segment.

**In OrcaSlicer:**

1. Create a calibration print: **Calibration > Flow Rate**
2. Set range: 0.85 to 1.15 in 0.02 or 0.025 increments
3. Print and inspect each segment

**What to look for:**

| Symptom | Flow Rate Issue |
|---------|----------------|
| Rounded, bulging corners | Too high |
| Rough top surface | Too high |
| Layer lines visible between segments | Too low |
| Gaps between wall lines | Too low |
| Smooth, flat top with crisp corners | Just right |

### Step 4: OrcaSlicer Built-in Calibration

OrcaSlicer has an excellent built-in flow calibration:

1. Click **Calibration > Flow Rate** (or **Calibration > Pass 1**)
2. OrcaSlicer generates a test print with varying flow rates
3. After printing, use the built-in measurement tool
4. Enter your measured wall thickness
5. OrcaSlicer suggests the new flow rate

This is the easiest and most reliable method for Voron printers.

---

## Pressure Advance Interaction

Flow rate and pressure advance interact. The calibration order matters:

### Correct Order

1. **Rotational distance** — Foundation
2. **Pressure advance** — Tune first (PA changes effective flow)
3. **Flow rate** — Fine-tune after PA is set
4. **Retraction** — Tune last

### Why PA First

Pressure advance slightly changes actual extrusion volume:

- **High PA values (0.06+):** May reduce effective flow on small features
- **Low PA values (0.01–0.03):** Minimal flow impact
- **Without PA:** Flow rate must compensate for ooze/blobs that PA would normally handle

**If you calibrate flow rate first, then add PA, you may need to re-calibrate flow.**

### Practical Approach


# Step 1: Set a reasonable PA (even if uncalibrated)
SET_PRESSURE_ADVANCE ADVANCE=0.045

# Step 2: Calibrate flow rate with this PA active

# Step 3: Fine-tune PA (it might change flow slightly)

# Step 4: Re-check flow rate if PA changed significantly
#    (e.g., if PA went from 0.045 to 0.030, expect ~1% flow change)


---

## Per-Filament Flow Rates

Different filaments need different flow rates. Build profiles:

### With Save Variables (Klipper)


[gcode_macro SAVE_FLOW_RATE]
description: Save current flow rate for a filament type
gcode:
    {% set filament = params.FILAMENT|default("default") %}
    {% set flow = params.FLOW|default(1.0) %}
    SAVE_VARIABLE VARIABLE=flow_{filament} VALUE={flow}
    M117 Flow rate {flow} saved for {filament}

[gcode_macro APPLY_FLOW_RATE]
description: Apply saved flow rate
gcode:
    {% set filament = params.FILAMENT|default("default") %}
    {% set flow = printer.save_variables.variables["flow_" ~ filament] | default(1.0) %}
    M221 S{flow * 100}
    M117 Flow set to {"%.3f"|format(flow)} for {filament}


**In PRINT_START:**

[gcode_macro PRINT_START]
gcode:
    # ... setup ...
    {% set ftype = params.FILAMENT_TYPE|default("PLA") %}
    {% set flow = printer.save_variables.variables["flow_" ~ ftype] | default(1.0) %}
    M221 S{flow * 100}
    M117 Using flow {flow} for {ftype}


### Slicer Profiles

Maintain separate slicer profiles per filament:


PLA:  flow 0.95, PA 0.045, temp 220
ABS:  flow 1.00, PA 0.035, temp 250
PETG: flow 0.92, PA 0.030, temp 240
TPU:  flow 0.98, PA 0.020, temp 230


---

## Typical Flow Rate Ranges for Voron Extruders

| Filament | CW2 / Clockwork | Galileo | Sherpa | Orbiter |
|----------|:--------------:|:-------:|:-----:|:-------:|
| PLA | 0.92–0.98 | 0.90–0.96 | 0.93–0.98 | 0.92–0.97 |
| ABS | 0.95–1.02 | 0.93–1.00 | 0.96–1.02 | 0.95–1.00 |
| PETG | 0.88–0.95 | 0.87–0.93 | 0.89–0.95 | 0.88–0.94 |
| ASA | 0.95–1.02 | 0.93–1.00 | 0.96–1.02 | 0.95–1.00 |
| Nylon | 0.95–1.02 | 0.93–1.00 | 0.96–1.02 | 0.95–1.00 |
| PC | 0.97–1.05 | 0.95–1.02 | 0.98–1.05 | 0.97–1.03 |
| TPU | 0.95–1.02 | N/A | 0.95–1.02 | 0.95–1.00 |

**Note:** These are starting ranges. Every filament roll is different. Always calibrate for each new spool.

---

## Advanced: Full Extrusion System Calibration

### Step 1: E-Steps (Rotational Distance)

Already covered above. This is non-negotiable for accuracy.

### Step 2: Filament Diameter Measurement

Measure filament diameter at 10+ points along 2 meters:


Measurements: 1.74, 1.75, 1.76, 1.74, 1.75, 1.75, 1.76, 1.74, 1.75, 1.75
Average: 1.749mm


Update slicer's filament diameter from 1.75 to 1.749 for this spool. (Small difference, but every bit helps.)

**Pro tip:** Store the actual diameter in `save_variables`:


SAVE_VARIABLE VARIABLE=fd_eSun_PLA_PRO_value=1.749


### Step 3: Nozzle Size Verification

Measure your nozzle orifice with a pin gauge or drill bit:

- 0.4mm nozzles often measure 0.38–0.42mm
- Update slicer if significantly off (±0.02mm matters)

### Step 4: Extrusion Width Settings

For Voron printers with 0.4mm nozzles, common extrusion widths:

| Feature | Width | Notes |
|---------|-------|-------|
| First layer | 0.44mm (110%) | Better adhesion |
| Walls | 0.42mm (105%) | Standard for .4mm |
| Sparse infill | 0.44mm (110%) | Faster infill |
| Solid infill | 0.40mm (100%) | Denser top layers |
| Internal bridges | 0.40mm (100%) | Better bridging |

### Step 5: Full Sequence Print

After individual calibrations, print a stress test:

- A Benchy or Voron cube
- Clean surfaces, good overhangs, sharp corners
- Measure with calipers — dimensional accuracy within ±0.1mm is excellent

---

## Troubleshooting Flow Issues

### Over-Extrusion Signs

**Symptoms:**
- Rounded corners (elephant's foot on corners)
- Rough top surface (pillowing or ridges)
- Visible blobs at layer seams
- Dimensional measurements larger than expected
- Gaps between infill and walls

**Fixes:**
1. Reduce flow rate by 2–5%
2. Check filament diameter (might be undersized)
3. Verify rotational distance
4. Check pressure advance (too high can cause over-extrusion at corners)

### Under-Extrusion Signs

**Symptoms:**
- Gaps between wall lines
- Weak or brittle parts
- Visible layer separation
- Thin walls (measure less than expected)
- First layer not bonding

**Fixes:**
1. Increase flow rate by 2–5%
2. Check for partial nozzle clog
3. Verify extruder tension
4. Check filament diameter (might be oversized)
5. Increase nozzle temperature (affects flow viscosity)
6. Check for heat creep in hotend

### Inconsistent Extrusion

**Symptoms:**
- Alternating thick/thin layers
- Periodic underextrusion
- Surface roughness varies

**Fixes:**
1. Check extruder gear condition (worn gears slip)
2. Verify extruder tension (too tight grinds filament)
3. Check filament quality (out-of-round, inconsistent diameter)
4. Increase extruder current (skipping steps?)
5. Check for debris in extruder path
6. Verify PTFE tube is fully seated in hotend

### First Layer Flow Issues

**Symptoms:**
- First layer too thin (transparent)
- First layer too thick (ridges)
- Poor adhesion despite correct Z offset

**Fixes:**

For a transparent first layer (under-extruded):

First layer flow: 1.05–1.10  (105–110% of normal flow)
First layer width: 0.48mm     (120% of nozzle)


For a ridged first layer (over-extruded):

First layer flow: 0.90–0.95
First layer width: 0.42mm


---

## Slicer-Specific Settings

### OrcaSlicer

OrcaSlicer has the best Voron flow calibration tools:

1. **Calibration > Flow Rate** — Generates the test print
2. **Calibration > Pass 1** — Quick single-wall test
3. **Filament Settings > Overrides > Extrusion multiplier** — Per-filament control
4. **Advanced > Flow ratio** — Alternative to extrusion multiplier

**Recommended settings:**

Filament Settings > Overrides:
  Extrusion multiplier: [calibrated value]

Quality > Precision:
  Wall generator: Arachne (better variable-width walls)


### PrusaSlicer / SuperSlicer

1. **Filament Settings > Extrusion multiplier** — Set calibrated value
2. **Print Settings > Extrusion width** — Keep as 0.44mm for 0.4mm nozzle
3. **Layer and perimeters > Quality (speed)** — Higher quality gives more consistent flow

### Cura

1. **Material > Flow** — Set percentage (e.g., 95%)
2. **Experimental > Enable "Use Arachne"** — For better wall handling
3. **Special modes > Print thin walls** — For fine features

---

## Integrating Flow Rate into PRINT_START

Combine calibration with your print start macro for full filament tracking:


[gcode_macro PRINT_START]
description: Start a print with per-filament flow settings
gcode:
    # ... homing, heating, mesh ...
    
    {% set ftype = params.FILAMENT_TYPE|default("PLA") %}
    {% set fbrand = params.FILAMENT_VENDOR|default("Generic") %}
    {% set flow_key = "flow_" ~ fbrand ~ "_" ~ ftype %}
    {% set flow = printer.save_variables.variables[flow_key] | default(None) %}
    
    {% if flow is not None %}
        M221 S{flow * 100}
        M117 Flow: {".0f"|format(flow * 100)}%
    {% else %}
        # Try generic type key
        {% set generic_key = "flow_" ~ ftype %}
        {% set generic_flow = printer.save_variables.variables[generic_key] | default(1.0) %}
        M221 S{generic_flow * 100}
        M117 Flow: {".0f"|format(generic_flow * 100)}% (generic)
    {% endif %}


---

## Maintaining Calibration Over Time

### When to Re-Calibrate

- **New filament spool** — Even same brand, different batch
- **Nozzle change** — Different size or brand
- **Extruder change** — Different gear ratio
- **Hotend change** — Different melt zone characteristics
- **After 100+ print hours** — Extruder gears wear

### Keeping a Calibration Log

Track your results:

| Date | Filament | Brand | Nozzle | Flow | PA | Temp | Notes |
|------|----------|-------|--------|------|----|------|-------|
| 2025-04-15 | PLA | eSun | 0.4 | 0.95 | 0.045 | 220 | Great results |
| 2025-04-20 | ABS | Polymaker | 0.4 | 0.98 | 0.035 | 250 | Needs drying |
| 2025-05-01 | PETG | Overture | 0.4 | 0.92 | 0.030 | 240 | Stringing reduced |

Store this digitally with `save_variables` or as a comment in your `printer.cfg`.

---

## Common Myths

### Myth: Flow Rate Should Always Be 1.0

**False.** Nearly every printer and filament combination benefits from slight adjustment. 0.92–0.98 is normal for most Voron setups with quality filaments.

### Myth: Higher Flow = Stronger Parts

**False.** Over-extrusion causes dimensional inaccuracy, poor inter-layer bonding, and can actually weaken parts by introducing voids and stress concentrations.

### Myth: Calibrate Flow Once and Forget

**False.** Filament batches, nozzle wear, and extruder condition all change over time. Periodic re-calibration keeps quality consistent.

### Myth: OrcaSlicer's Auto-Cal Replaces Manual Tuning