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Cut Settings - Fill Mode

Fill mode has different settings, shown below:

'Fill mode' was called 'Scan' in older versions of LightBurn, because it scans back and forth across the shape, but was renamed to 'Fill' to make it easier to understand for new users.

Bi-directional Fill

When enabled, the laser will engrave in a side-to-side sweeping motion, engraving in one direction and again for the return direction. When disabled, the laser will engrave traveling one way, then return to the start of the next line, not engraving the return pass.

Cross-Hatch

When enabled, runs a second engraving pass at 90 degrees from the first.

Overscanning

When enabled, adds extra moves to the beginning and end of each line to give the laser time to speed up before firing, and slow down afterward. If your machine has low acceleration or you see darker burns at the sides of your fills, you may need to increase the amount of overscanning. If you do not see this setting, your machine is likely a DSP controller and handles this automatically in hardware.

Line Interval

Controls the spacing between scanned rows, and indirectly controls 'Lines per Inch'.

Lines per Inch

A different, often more intuitive way of controlling the line interval, or spacing between rows.

Scan Angle

Normally 0, meaning the laser will scan back and forth horizontally across the image, progressing from the bottom of the image to the top. If you set this to 180, the laser will scan the image from top to bottom. Setting this to 90 will scan the laser vertically over the image, progressing from left to right.

NOTE: If you have a DSP controller, we do not advise using angles that aren't a multiple of 90 degrees. Horizontal and Vertical scanning is supported natively by the hardware, and it will automatically handle over-scanning beyond the sides of the image to get the head to full speed before engraving starts. Scanning at non-90 degree angles is "emulated" using normal cutting moves. It works, but it's mostly useful as a style option, and not recommended for general use.

Number of Passes

Sets how many times the laser will run this filled shape.

Z Offset

If Z moves are enabled, this setting controls how much to raise or lower the Z axis when executing this fill. Lifting the laser a few mm, for example, can make the beam wider, allowing the use of larger interval values, which can make filling a large area faster.

Z Step per Pass

If using multiple passes, and Z control is enabled, this number controls how much to move the Z axis between passes. This could be used to shift the focus into the material on subsequent passes if you are engraving for depth.

Fill Grouping

These options control which shapes are filled at the same time on the laser. If you run your laser fast, OR your laser accelerates slowly, it is often most efficient to scan things all at once, so the laser spends most of its time moving at the speed you've chosen, and less time changing direction. If you are engraving slowly, or your laser accelerates fast, or the design contains a lot of blank space, it can be more efficient to fill clusters of close shapes, or just fill the shapes one by one. If you aren't sure, try different options and use the preview to estimate the time.

  • Fill all shapes at once: The default, this setting means that everything on this layer will be filled at the same time, sweeping back and forth across the whole job. If you are running the laser fast (300 mm/sec or more) this is usually the most efficient option, with some exceptions.
  • Fill groups together: This setting will fill all shapes in a group at the same time.
  • Fill shapes individually: This setting fills all shapes one by one.

Advanced settings

Under the Advanced tab you'll find a couple useful, but less frequently used options.

Ramp Length

This setting can be used to slope the sides of an engraving by varying the laser power, and is useful if you create rubber stamps, particularly if the designs have thin regions that need extra support. The ramp length controls how far from the design the slope will extend.

Note: On a DSP controller, the ramp varies the laser power from Min Power to Max Power, so you must set these differently to get a ramped side. Typically you would set Min Power to be just above the firing threshold of your laser.

Flood Fill

This option is incredibly useful when you need it, but is very sensitive to machine tuning and backlash, and can end up leaving gaps in your engraving if the design is complex and/or your machine is not set up optimally. Flood fill tries to eliminate travel moves across blank space, so it's perfect for engraving something like a large, empty rectangle, where the blank area in the middle would consume most of the time spent.

If used on complex designs, Flood Fill can produce engraving paths that jump around a lot, and return later to fill in missed spots, which is why it can leave gaps if the machine isn't well tuned. Use it sparingly, and use the Preview tool to see how the option will engrave your design so you aren't surprised by the path it takes.

Fill + Line Mode

Performs a fill, then traces the outline, with a limited subset of line-mode features. This is useful for doing things like adding definition to the outlines of text, and can let you use a lower interval value (line distance) for the fill.

Fill+Line mode will run the fill first, then use the settings in the 'Line (after fill)' tab for the lines. Setting high speed and low power, for example, would just trace the outlines for added definition. Using high power and low speed could cut out the shapes after engraving them.