EveryCutFileWhat kerf does to a part
The cut runs along the middle of your line, and half of the burned width falls on each side of it. These examples use a 0.2 mm kerf.
| You draw | It comes out | Why |
|---|---|---|
| A 20 mm square piece | 19.8 mm | Each edge loses 0.1 mm |
| A 20 mm square hole | 20.2 mm | Each edge gains 0.1 mm |
| A 3 mm slot for 3 mm plywood | 3.2 mm, so the tab rattles | Draw the slot 2.8 mm, or offset it inward by 0.1 mm |
| A 1 mm bridge between two cuts | 0.8 mm | Both of its edges lose 0.1 mm |
Measure your kerf
- Make a 20 mm test square with the kerf tool, with any kerf offset switched off.
- Cut it from the material you will use, at the power and speed you will use.
- Measure the square piece across two straight edges with calipers.
- Kerf is 20 mm minus the piece. Enter both numbers in the kerf tool to see the hole size too.
- Measure again when you change material, thickness, lens or settings.
A worked example
Our square keychain blank is 45 × 45 mm. Cut from plywood with a 0.2 mm kerf, it comes out 44.8 mm. That rarely matters for a keychain, but for a part that must fit a slot or a frame, offset the outline outward by 0.1 mm and it comes out 45.0 mm.
Minimum feature size: four different things
| Feature | What to check |
|---|---|
| Gap | Empty space between neighboring outlines; kerf makes it wider |
| Bridge | Material that holds two areas together; kerf makes it thinner |
| Loose piece | A small part that must survive cutting and handling |
| Stroke | A line width; your software may cut it as a single centerline |
Test your own smallest cut
Cut a strip of bridges at 0.5, 1, 1.5 and 2 mm in your material and keep the thinnest that survives handling. Enter that width in the checker: it flags rectangles and strokes thinner than it, and leaves complex outlines for you to judge. A blade cutter removes almost no material, so kerf matters little there; the limit is how small a piece the blade and mat can hold.