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Laser & CNC Maker Tool

Laser Cutting Kerf & Fit Offset Calculator

Calculate laser beam kerf compensation, slot cut dimensions, and vector path offsets for finger joints, mortise & tenon tabs, acrylic inlays, and press-fit boxes across Glowforge, LightBurn, xTool, and CO2/Diode laser cutters.

Estimated Beam Kerf Width
0.18 mm (0.0071 in)
Cut Path Vector Offset (Radius)
+0.09 mm
Offset outer contours outwards; inner holes/slots inwards.
Target Slot Cut Width in CAD/DXF
3.03 mm
Tight Press-Fit Calibration
Laser Path (Centerline) vs Actual Material Edge

Why Vector Path Precision Dictates Joint Quality

When a laser cuts material, the laser beam vaporizes a narrow width of material known as the kerf (typically between 0.10mm and 0.25mm depending on laser wavelength, focal spot size, and air assist). If your vector DXF/SVG geometry does not compensate for this beam diameter, interlocking finger joints will be loose and wobbly, while inlays will show unsightly gaps.

1. Inside vs Outside Offsets

For male tabs, add half the kerf (+offset). For female slots or internal cutouts, subtract half the kerf (-offset) so that after beam vaporization, the physical part matches nominal dimensions.

2. Raster Images Fail in Lasers

Raster files (PNG/JPG) have fuzzy pixelated edges that LightBurn or laser controllers must threshold, creating jagged stair-stepped burns. Clean mathematical vector paths ensure continuous single-pass cuts.

3. Clean DXF & SVG Cut Paths

SpotItLive converts your bitmap artwork, hand sketches, and custom logos into continuous mathematical curves with zero duplicate overlapping nodes, ensuring high-speed, zero-char cutting.

Step-by-Step Kerf Test Gauge Workflow

To measure the exact kerf of your specific machine, lens, and material batch:

  1. Cut a rectangular test gauge with 10 identical slats (e.g. 10mm wide each = 100mm total nominal width).
  2. Push all 10 cut slats tightly together against a straight edge.
  3. Measure the total combined width with digital calipers (e.g. 98.2mm).
  4. Calculate Kerf = (Nominal Width - Measured Width) / Number of Cuts. Example: (100 - 98.2) / 11 = 0.163 mm.

Need Machine-Ready Vector Files (DXF, SVG, PDF) for Your Laser?

Convert low-res logos, raster illustrations, and hand sketches into clean, closed vector cut paths formatted specifically for LightBurn, Glowforge, and CNC plotters.

Convert Your Design — From 29 DKK