Glossary · Calibration

3D printing

Input shaping

A function of the printer firmware that compensates for vibrations in the mechanics. This keeps surfaces smooth even at high speed.

Explained in more detail

When direction changes quickly, the mechanics keep vibrating, and ripples appear on the surface behind edges, known as ghosting or ringing. Input shaping determines the printer's resonant frequencies, usually with an accelerometer, and shapes the motion commands so that these vibrations cancel each other out. There are different shaper types. Klipper lists ZV, MZV and EI, among others, and recommends MZV or EI for most printers. The Klipper firmware introduced input shaping at the end of 2020, and today it is active out of the box on many printers. Loose belts or a wobbly frame should be fixed first, as input shaping does not replace solid mechanics.

Where does the term come from?

The name means shaping the input signal. The term comes from control engineering: the control commands are shaped so that a system prone to oscillation comes to rest without ringing.

In practice

• Recalibrate after moving the device or rebuilding it, as the surface and mechanics change the natural frequencies.
• According to Klipper, printers without an accelerometer can also be tuned with a test print: you calculate the frequency from the spacing of the ripples.
• Shapers smooth fine detail somewhat. Choose the acceleration so that hardly any ripples remain, without corners becoming visibly rounded.
• Manufacturers sometimes call the function something else, such as vibration compensation or resonance compensation.

Not to be confused

Input shaping depends only on the mechanics and applies to all materials. Pressure advance, by contrast, compensates for material flow and is set per filament.

Frequently asked questions

Do I need an accelerometer for input shaping?

Not necessarily. Klipper also describes setting it via a test print. With a sensor it is faster and more accurate, which is why many current printers have one built in.

What is the difference between filters such as MZV and EI?

According to the Klipper documentation, filters that cover a wider frequency range damp more vibrations but smooth the parts more. ZV smooths the least but reacts most sensitively to a wrongly measured frequency.