Laser cutter kerf

Has anyone measured the kerf on the laser cutter recently?

The holes I cut for the #6 screws in my clock fit snugly around the screw, just like I was expecting. However, I just found out that I had misread the tables, and programmed in 0.1285 diameter holes for screws which are 0.1380 in diameter. The “proper” close-fit hole diameter should have been 0.1440, or 0.0155in.

That’s about twice what some sources suggest the kerf for 3mm birch plywood should be (about 0.2mm/0.008in). And I was getting that in the cardstock about have the thickness as well, where the kerf should be half that again (0.08mm/0.003in).

I can’t find the calipers to make a test run.

thanks for this note. i think @Bez or @Mark_Zifchock told me calipers were in a drawer somewhere.

There are some calipers which float between next to the laser cutter and atop “Scarab” terminal in front room. useful tool!

RE: kerf it has been my observation than kerf expands and cutting efficiency decreases in at least two common circumstances.

1 Focus length not properly set or material is warped (common with the hobby board I’m using). A warped board can lift up in funny ways and cause bad cuts where it moves out of the focal range. Haven’t found a good solution. Maybe something about storing blank material horizontally and off the concrete floor which wicks moisture?

2 Mirror/lens dirty. these can be removed from the machine by hitting x/y off and moving the cutting head to somewhere accessible, removing the lens and mirror, and gently cleaning with optical solution and special paper, found in adjacent cabinet. Lens screws out of the bottom of the moving head by turning a knurled brass ring (remember, upside town means turn the other way). It’s all one piece. Mirror is on top at a 45 degree angle, removal is the the same, via knurled brass ring.

I clean them once in a while when getting poor results and have seen improvement. I think smoke particles/vaporized wood sap and plastic residues build up over time.

Hope that’s helpful to someone!