Rotation Volume calibration

How to calibrate the Rotation Volume for a new pellet material in Ginger Slicer. This is the pellet equivalent of “flow calibration” on filament printers — and it’s the first thing to tune when starting a new material.

What Rotation Volume is

Rotation Volume = how many cubic millimetres (mm³) of plastic come out of the nozzle for one full turn of the extruder screw.

When Pellet Modded Printer is enabled in Ginger Slicer (default), the E value in G-code is interpreted as cubic millimetres of volume, not millimetres of filament. So E = 100 means “push 100 mm³ of plastic”.

The Rotation Volume tells the firmware how much screw rotation is needed to deliver that volume. Different materials — and even different grades of the same polymer — have different Rotation Volumes (variation up to 40% between PLA and PETG).

How the machine makes millimetres into cubic millimetres

Klipper has no idea what a pellet is: it thinks in millimetres of filament pushed through a nozzle. The G1 gets around that with one number in its configuration — the “filament diameter” is set to 1.1284 mm, whose cross-section is exactly 1 mm².

With a 1 mm² cross-section, one millimetre of “filament” is one cubic millimetre. Every flow figure on the machine — Rotation Volume, MVS, the extrusion readout — falls out of that single trick.

That diameter is not arbitrary: the slicer derives it from the Pellet flow coefficient in the material profile, which is 1 in everything Ginger ships. See Material profiles.

Note

Rule: do not modify firmware “rotation distance” values for pellets. Tune Rotation Volume in the slicer material profile.

When to do this

• Starting with a brand-new pellet material (different supplier, recycled, custom blend)
• Print quality is consistently off — bulges, gaps, lines wider/narrower than planned — even though the height is right
• After confirming temperatures are stable on all three Multi-Heating Zones

Prerequisites

• Pellets dried (PETG/PETG-V0 mandatory; PLA recommended)
• The three Multi-Heating Zones tuned and stable
• A clean nozzle and bed
• A simple cube model with a single skirt
• A caliper (or thickness gauge)
• About 30–45 minutes

Steps

A. Set up Ginger Slicer

1. Confirm Pellet Modded Printer is enabled (it’s the default)
2. Choose or duplicate a material profile close to your pellet (start from a Ginger profile or duplicate “Generic”)
3. Set Flow to 100% — leave it untouched throughout calibration
4. In First Layer settings, decide your line width and height (e.g. width 3.5 mm, height 1.5 mm)
5. Verify the values in Preview
6. Use the default first-layer speed (~50–70 mm/s)
7. Make sure no melting happens in the Feeding Zone (no soft pellets at the throat)

B. Print the test cube

Print a simple cube with a single skirt. You’ll calibrate from the first layer / skirt itself.

C. Set the height correctly first (Z offset)

Caution

Don’t skip this. Width measurement is meaningless until height is correct.

1. While the first line is printing, press Pause on the printer display
2. Measure the height of the printed line on a straight segment with the caliper
3. Compare to the slicer’s first-layer height
4. If the measured height is less than the slicer value, the nozzle is too low — raise it via live Z offset
5. If it is more, lower it
6. Resume and repeat until height matches what you set in the slicer
7. Only continue when height is correct

See Z offset and first layer for help.

D. Measure the line width

1. On a straight segment of the same line (avoid corners, overlaps), measure the width with the caliper
2. Take three readings along the skirt; use the average

E. Adjust Rotation Volume

Compare the measured width with the width you planned, then apply the formula below.

The direction catches people out, so it is worth understanding rather than memorising:

Rotation Volume is a statement about the material — how much it actually delivers per screw turn. The slicer works out how many turns to ask for by dividing the volume it wants by that number.

So if the line comes out too wide, the material is delivering more per turn than you told the slicer. You correct that by raising the figure to the truth: the slicer then asks for fewer turns, and the right amount comes out.

• Line wider than planned → increase Rotation Volume
• Line narrower than planned → decrease Rotation Volume

The formula

new Rotation Volume = (measured width / planned width) × old Rotation Volume

Quick examples

Starting from Rotation Volume = 460 mm³, planned width = 3.5 mm:

Measured width	New Rotation Volume
3.7 mm	~487 (+5%)
3.9 mm	~512 (+10%)
4.0 mm	~525 (+15%)
3.2 mm	~420 (−10%)
3.0 mm	~395 (−15%)

Where to change it

In Ginger Slicer:

1. Open the material profile
2. Find Rotation Volume (mm³ per screw turn)
3. Edit the value
4. Save the material
5. Re-slice and reprint the first layer

F. Validate

• Reprint the first layer with the new Rotation Volume
• Measure the width again
• If within ±5% of the planned width → done
• If not → one more small adjustment, repeat

G. Save the material

When satisfied, save the material profile with a clear name:

[Supplier]_[Polymer]_[Grade]
e.g. Formfutura_rPLA_natural

This way you can switch pellets in the future without recalibrating from scratch.

Rotation Volume is not a flow control

This is the part that gets misused, so it is worth being blunt about.

Rotation Volume is a property of the material. It says how much plastic leaves the nozzle for one turn of the screw — a fact about that pellet, not a setting you lean on to get a different result.

Do not scale Rotation Volume to change how much you extrude

If you want thicker or thinner walls, change the thickness in the slicer. That is what the setting is for.

Scaling Rotation Volume to force more or less material out makes the machine lie to itself: every flow figure downstream — the requested volume, the MVS, the extrusion readout — is computed from it, so they all become wrong together while the numbers on screen still look normal.

There is exactly one reason to change Rotation Volume: you printed, measured with a caliper, and the thickness does not match what the slicer said it would be. Then, and only then, you correct the figure to the truth.

Flow vs. Rotation Volume — don’t mix them up

	Rotation Volume	Flow
What it is	A property of the material: the volume that leaves the nozzle per screw turn	A small finishing tweak, a few %
When to change it	Only when a caliper says the printed thickness differs from the slicer	Last, for surface polish
Range	Material-specific, can vary 40%	Stay near 100%

Order of operations: Z offset → measure width → adjust Rotation Volume → re-slice → validate → optional tiny Flow tweak at the end.

Troubleshooting during tuning

Issue	Action
Width varies up and down	Dry pellets, slow first layer, stabilize temps
Melt creeping into feed throat	Lower Feeding Zone or use larger nozzle; see Multi-Heating Zones
Can’t reach planned width	Recheck Z offset; confirm Flow is still 100%
Bubbles / foam	Pellets wet — see PETG foaming and moisture

Adjusting Rotation Volume from a finished print

If a completed print shows walls or lines consistently wider or narrower than the CAD model, you don’t need to reprint from scratch. Use the same formula directly on the finished part:

new Rotation Volume = (actual_measured_width / target_width) × current_rotation_volume

Example: 5 mm nozzle, slicer set to 6 mm wall, actual wall measures 7 mm:

new RV = (7 / 6) × 456 = 532

Note

This is the same correction as during calibration, applied to a finished part instead of a first layer — the direction is explained in step E.

FAQ

Q: Should I change firmware “rotation distance” for pellets? A: No. Leave firmware alone. Use Rotation Volume in the slicer material profile.

Q: When do I touch Flow? A: Only after Rotation Volume is correct, and only for small surface-quality tweaks (a few %).

Q: My measured line is thinner than planned. What now? A: Lower Rotation Volume by roughly the percentage difference.

Final verification

• Print a small test object (cube, vase) with the calibrated profile
• Layers look uniform, no bulges, no gaps
• Layer width and height match Preview within ±5%

Related notes

• Ginger Slicer
• Multi-Heating Zones
• Max Volumetric Speed
• Z offset and first layer
• Creating a material profile

Sources

• Ginger Academy — Flow Control for Pellets: Know Your True Volume