Kerf Laser Cutting
I recently completed my first laser cut project, a stand for phones. The project itself is basically four pieces of MDF slapped together with a couple of finger joints and a little bit of glue just for some added security.
Laser cutting is a process of removing material but I’d never though about the fact that material was removed around the cut, only that a cut was made. I’ve sawed off things in the past, but the required precision was not too strict so the fact that the sawdust piled up didn’t bother me.
If you want to create multiple parts that have to be combined, you are going to need higher precision and therefore you need to know about kerf.
Kerf is the width of material that is removed when cutting. Kerf is caused by mutliple factors; The material’s properties, the laser and its angle towards the surface that is being cut, just to mention a few. Kerf can also differ horizontally and vertically.
Below is an attempt to visualize it.
removed material v ------------- v | | | | | | | | | | | | | | | ^ laser cut line
Many shops that provides laser cutting will have a table specifying how wide kerf can be expect for materials at certain thicknesses. If your shop or your own cutter doesn’t specify this, I suggest that you order a test piece or see if someone has experience with that shop.
A test piece could be square, let’s say 30mm x 30mm. Have it cut and measure it with a caliper. Measure the piece and subtrack the value from the original value. You can repeat the following process to get vertical and horizontal kerf. Hopefully they are the same. 🤞
Let’s imagine that the square turned out to be 29.5 mm x 29.5 mm, then we have a kerf of:
30 - 29.5 = 0.5
kerf 0.5 mm v ------------- v v 0.25 | 0.25 v 30x30 | | | source square | | | material | | | | | | | | | ^ laser cut line ^ -------------- ^ removed material
The laser is cutting along the center line, only half of the kerf is affecting our cube but since it’s being cut twice horizontally and vertically it’ll be the whole kerf in the end.
To get the square to be 30 mm x 30 mm, we need to offset the cutting line by half of the kerf on every side.
_____________ < laser cut line | < removed material | _________ | | square | | ^ offset of 0.25 mm
I hope this has cleared out some confusion, it has for me atleast!