Overscan

When the head accelerates and decelerates, it spends a moment changing speed. If the laser fires during those moments, the start and end of each fill line get more energy than the middle (because the head moves slower there), burn-in.

Overscan solves this by having the head travel past the edge of the fill before turning around. The laser turns on / off at the actual fill boundary, but the deceleration / acceleration happens beyond the boundary.

The basics

For a fill that goes from X=0 to X=100, an overscan of 5 mm means the head moves from X=-5 to X=105 each line. The laser is off in the overscan regions; it fires only between X=0 and X=100.

The result: every fill line gets uniform energy.

How Beam Bench handles it

Overscan is added automatically by the planner based on the layer's speed and the machine's acceleration profile. You generally do not configure it manually.

The Preview window has a Show Overscan toggle that visualizes the overshoot region, useful for verifying the planner is doing what you expect.

The Output Policy in the machine profile has a Use G0 for Overscan toggle that emits the overscan as rapid (G0) moves instead of feed (G1) moves. The default is enabled, so Beam Bench emits overscan travel as G0.

When it matters

• Engraving solid fills on contrast-sensitive material (anodized aluminum, leather), without overscan, the edges look darker than the center.
• High-speed engraving: the higher the speed, the longer the acceleration / deceleration distance, the more overscan helps.
• Tight fills near work boundaries: make sure your design has enough margin around the fill for the overscan distance. The Preview shows whether it does.

Related

• Preview dialog: Show Overscan toggle
• Device Settings dialog: Output Policy
• Scan interval
• Fill modes