An image for a post on the HAD blog.

The transparent graticle on my microscope easily shows the spot size of the laser at my hackerspace. I conclude from this that the "kerf" of our laser is about 0.02 inches (20 thou).

Using a micrometer and some precision-ground rods, a 6mm hole measures out as 6.052mm. Considering 0.02 inches as 0.508mm, 90% of the kerf is inside the hole and 10% is outside.