Max Volumetric Speed (MVS)

The maximum rate, in cubic millimeters per second (mm³/s), at which the G1 pellet extruder can melt and push out plastic. MVS is what the extruder can deliver — but it is rarely the number that decides how fast a good print finishes.

Why MVS matters

Set too high, the screw can’t push enough material against the back-pressure. The extruder stepper draws maximum torque, can’t deliver, and starts skipping steps. You’ll hear the characteristic “tak-tak-tak” and see the screw coupler jerk instead of rotating smoothly.

The G1’s mechanical kinematic limit is about 300 mm/s. You’ll rarely reach that — extrusion is what slows things down. Recommended print move speeds:

Normal printing moves: 120–150 mm/s
Travel moves: up to 300 mm/s

What actually limits throughput

Three different things cap print speed, and which one is in charge depends on the setup:

Limit	When it takes over
Extruder motor torque (E0)	The limit that defines MVS. When the material demands more torque than the motor can deliver, the motor skips
Kinematics	With small nozzles — consuming the full MVS would need move speeds beyond what the motion system can do, so print speed caps out first
Layer time	In practice, on any print you actually want to keep. Each layer has to cool before the next lands on it

Everything that raises achievable MVS — SmoothFlow, higher temperature, a larger nozzle — works by reducing the torque the screw needs, not by making some other part of the machine faster.

Situation	MVS
What the shipped profiles set	200 mm³/s for almost every material — see Material profiles
Larger nozzles	above 300 mm³/s
Specific PETG grades — e.g. SKYgreen SF200	up to ~500 mm³/s. Not standard — depends entirely on the grade
With Liquid Masterbatch	reduce — masterbatch lowers screw grip

MVS vs. nozzle diameter

Smaller nozzles increase back-pressure and reduce achievable MVS:

Nozzle	Max MVS (mm³/s)	Example layer	Print speed
8 mm	~500	10 mm × 5 mm	~10 mm/s
3 mm	~300	4 mm × 1.5 mm	~50 mm/s
1 mm	~150	1.2 mm × 0.6 mm	~208 mm/s

These are ceilings. There is a floor as well: run the flow low enough and the barrel inlet starts to plug, because the pellet flow is what carries heat away from the feed throat. It is a window rather than a line — the risk appears below roughly 150 mm³/s and becomes real around 100.

Read the 1 mm row against that and the two meet. Its ceiling is 150, so the 1 mm nozzle never gets out of the clog window — it works inside it always, and its Feeding Zone has to be kept low as a matter of course rather than as a fix. See Nozzle and barrel clog.

Note how the bottleneck moves as the nozzle gets smaller. At 8 mm the extruder is the limit and the machine crawls at 10 mm/s. At 1 mm, consuming the full 150 mm³/s would require 208 mm/s — above the 120–150 mm/s recommended for print moves — so the motion system, not MVS, sets the pace.

Symptoms of MVS too high

Stepper motor “clicks” or “tak-tak-taks” — see Extruder motor skipping
Screw coupler visibly jerks (look from the right side of the extruder)
Under-extrusion at high-flow regions (infill, large features)
Audible torque struggle from the motor

Fixing high-MVS issues

When the motor skips:

Reduce print speed in real time from the display or Mainsail until smooth
Stop the print and lower MVS in Ginger Slicer before restarting

To recover lost speed without lowering MVS:

Raise the temperature by 5–10°C — softer melt needs less torque
Add SmoothFlow — less friction, so the screw needs less torque for the same flow
Combine both — usually the most effective

Both work the same way: they lower the torque the motor has to supply.

Switching to a larger nozzle without increasing MVS

A common mistake: switching from a 3 mm to 8 mm nozzle but keeping the same MVS (e.g. 250 mm³/s). The larger nozzle can theoretically flow much more, but the slicer is still capped at the old value → the print takes longer, not shorter.

Fix: when switching to a larger nozzle, raise MVS in the material profile to match the new nozzle — take the figure from the material profile rather than carrying the old one over.

Special considerations

Liquid Masterbatch + high MVS

Masterbatch reduces the friction between pellets and screw. At high MVS, the screw stops “biting” and you get under-extrusion. Lower MVS or reduce masterbatch percentage to restore grip.

Insufficient layer cooling

If small parts deform, layers haven’t cooled in time. Don’t fix with MVS — increase Min Layer Time in the slicer’s cooling section.

This is the same limit described in What actually limits throughput: on a print that comes out well, layer time is what governs, and no MVS value can buy speed back from it.

Where to set MVS

In Ginger Slicer:

Open the material profile
Find Max Volumetric Speed (under speed/cooling settings)
Set the value
Save the profile and re-slice

Tuning workflow

Start at the safe value for your material
Slice and print a test cube
Listen — any “tak-tak”? Any irregular extrusion?
Yes → lower MVS by 25 mm³/s, retest
No, smooth print → optionally try increasing temperature or adding SmoothFlow to push higher
Save the final value in your material profile

Sources

Ginger Academy — Ginger Slicer