Definition

A slicer can write explicit Z moves before and after travel, or firmware retraction can apply a configured lift with G10/G11. The physical direction depends on machine kinematics, but the intended nozzle-to-part clearance increases during the crossing.

Z-hop can reduce scarring and collisions with curled edges, yet it adds motion and time and may worsen stringing by extending travel. It does not replace correct bed leveling, extrusion or part cooling, and an unsafe lift can exceed axis limits near maximum build height.

What matters in practice

Temporary height change

A hop should be paired with a return before the next printed path.

Two encodings

It may be explicit Z G0/G1 motion or hidden inside firmware-retraction settings.

Tradeoff, not cure-all

Extra clearance can help with contact but adds travel time and cannot fix warped geometry.

Example in G-code

Explicit 0.4 mm hop

G91
G0 Z0.4 F600
G90
G0 X100 Y80 F9000
G91
G0 Z-0.4 F600
G90

Raises Z relatively, travels, lowers by the same amount and restores absolute mode.

What this viewer can show

In this viewer

Explicit Z-hop moves appear in the rendered travel path and height timeline. A hop hidden in G10/G11 firmware settings is only measurable when the file or metadata states its value.

Primary sources

This explanation uses firmware documentation and details visible in G-code. Your printer's settings still determine what the machine does.