Inlay kerf offset calculator

Kerf offsets for laser-cut inlays: how far to grow the insert and shrink the pocket so wood, acrylic or veneer inlays fit without a gap, with a glue allowance.

An inlay is cut twice: the insert from one material, the pocket from another. Each cut loses half a kerf on every edge, so with no correction the pocket is too wide and the insert too narrow and the gap shows. Enter the kerf of each cut and the glue gap you want, and get the per-side offset to apply to each.

Why both offsets

The two cuts run on different materials, often with different settings, so they rarely have the same kerf; measure each with the kerf test gauge. Growing the insert by half its kerf and shrinking the pocket by half of its own puts both back at the drawn line. Then take half the glue gap off each so the glue has somewhere to go: 0.05 mm total is a press fit, 0.1 mm slides in with a little play, 0 is for inlays you tap in dry.

Tips from the bench

• Cut the pocket first and test the insert on scrap before cutting the real piece.
• Flip the insert over if the top edge of the kerf is wider than the bottom (it usually is): the taper then matches the pocket.
• Veneer and thin acrylic: keep sharp inside corners in the drawing, the laser cuts them; a router could not.
• Fill tiny gaps with sawdust from the insert and CA glue; they sand away invisibly.

Related tools

• Sheet gauge ⇄ mm: Gauge to millimetres and back for steel, stainless, aluminum and SWG, with the tables.
• Nesting efficiency calculator: Compute utilisation, waste and material cost from total part vs sheet area.
• Sheet utilization calculator: Quick grid estimate of how many rectangular parts fit on a stock sheet.

FAQ

Is the offset the whole kerf or half?

Half, per side. The laser centres on the line and removes half the kerf each side of it, so each edge moves half a kerf; the offsets here are already per side.

Can I just set the same kerf on both layers?

If both materials cut with the same kerf, yes: +kerf ÷ 2 on the insert, −kerf ÷ 2 on the pocket, minus half the glue gap each. Different materials usually want different values.

What if my software has no kerf offset?

Offset the paths in the drawing (Inkscape: Path → Outset/Inset with the step set to these values; Illustrator: Object → Path → Offset Path) and export two files.