Just got done reading the write up Laser Cutter Kerf Measurement and wanted to take a minute to share our own method.
Early on we created a template of the kerf sizes we saw the most frequently with the materials we use. The template (shown below) contains 9 squares. The center square is the ‘Control’ square then each of the outter squares contains a square with the dimensions increased by double the kerf we want to test. Then we are able to compare the pieces that come out with the center piece to determine the kerf of that material. It also allows us to test sizes that may be both higher and lower in size to see what will work for either loose or tight press fitting.