Kerf compensation
Kerf compensation
When the laser cuts, it removes a strip of material called the kerf. A cut centered on the design line removes material from both sides of that line, so exterior parts usually come out smaller and interior openings usually come out larger than the design.
The exact kerf depends on the machine, material, thickness, focus, power, speed, and other process conditions. Do not treat a range associated with a broad laser category as authoritative for your setup. Measure the result produced by the settings you will actually use.
Current Beam Bench behavior
Expand a Line sublayer's vector controls and set Kerf Offset in the displayed unit. The value is the path offset, usually half the measured cut width. Positive values expand outer contours and shrink nested holes; negative values reverse this. Zero disables compensation. Preview and machine output use the compensated paths; artwork stays unchanged.
Only closed Line contours are compensated. Open paths, raster and Offset Fill are unchanged. A contour that collapses or splits stops planning with an error. Compensation can extend output beyond artwork bounds, so check Preview and clearance. Avoid applying both explicit geometry offsets and kerf compensation to the same contour.
Measure the kerf
- Draw a simple test square and cut it from the same material with the same focus, power, speed, and air-assist setup planned for the real job.
- Measure the part with calipers.
- Subtract the measured dimension from the design dimension. The difference is the total kerf loss for that axis.
- Divide the total loss by two to obtain a starting kerf radius.
- Cut and measure an interior opening as a second check.
For example, if a 50 × 50 mm design produces a 49.8 × 49.8 mm exterior part, the total loss is 0.2 mm and the starting radius is 0.1 mm. These are metric reference values. Convert design dimensions and the radius to the unit shown by the current Display Unit before entering them; Beam Bench stores geometry internally in millimeters.
Treat the result as specific to that exact setup. Re-measure when the material, thickness, focus, or cutting settings change.
Nest
Nesting positions artwork before kerf compensation. Allow clearance for the resulting cut paths and check Preview.
Verify before cutting real parts
Preview and cut the compensated exterior part and interior opening on scrap. Measure both with calipers and test the intended fit. If either result is wrong, adjust the offset and repeat the scrap test.
Do not produce the real parts until the compensated scrap result matches the intended dimensions and fit.
When it matters
- Slot-and-tab assemblies: the slot and tab dimensions determine whether the parts fit.
- Press-fit parts: a small dimensional error can change a snug fit into a loose or impossible one.
- Gear teeth: kerf changes the effective tooth profile.
For decorative engraving and isolated shapes that do not need to fit another part, kerf often does not matter.