### What is kerf?

Every time the laser cutter makes a cut, it burns away a small amount of material–this margin of error is called the “kerf”. In some cases, the kerf can differ considerably for horizontal and vertical cuts (as is the case with our laser cutter). When designing parts that fit together, you will need to compensate for this. Here is a good illustration of kerf.

### How do you measure the kerf?

The kerf is different for every material, and varies with material type, thickness, and the power used to cut the material. The quickest, most precise way for you to determine the kerf is to come in to the fabrication lab so that we can do a quick o.5″ x 0.5″ test cut in your material. By measuring the actual size of the resultant piece–and comparing this to the intended size–we can determine the exact kerf for your material. However, for your convenience we have listed the kerfs for all the materials we sell below.

### Now that I know the kerf, what do I do with it?

The kerf is a subtractive error–this means that every time the laser makes a cut, the hole that is left is slightly larger than the shape created you created in illustrator, and the piece which comes out is slightly smaller.

Therefore:

**For a fitted negative shape **(the cut-out left in your material), subtract the vertical kerf from your height for every vertical cut and subtract the horizontal cut from your width for every horizontal cut. *For example, for a square cut-out intended to be 0.5″ x 0.5″ with .002 vertical kerf and .004 horizontal kerf, the square would need to be (o.5-2(vertical kerf))” x (0.5-2(horizontal kerf))” = .496″ x .492″*

**For a fitted positive shape** (the piece cut out from the material), add the vertical kerf from your height for every vertical cut and add the horizontal cut from your width for every horizontal cut. *For example, for a square piece intended to be 0.5″ x 0.5″ with .002 vertical kerf and .004 horizontal kerf, the square would need to be (o.5+2(vertical kerf))” x (0.5+2(horizontal kerf))” = .504″ x .508″*

### Kerfs for Materials Sold in the Fabrication Lab

Material | Thickness (exact) | Horizontal Kerf | Vertical Kerf |

1/8” Birch | .127” | .002” | .006” |

1/4” Birch | .227” | .0015” | .0035” |

1/4” MDF | .238” | .003” | .005” |

1/8” MDF | .118” | .003” | .006” |

1/4″ Acrylic (clear) | |||

1/8” Acrylic (clear) | |||

1/8” Acrylic (white) | .118” | .004” | .005” |