Im building Elmer's 46 Comber. In the process of laying out the cam per Elmer's instructions I found out how old Ive become as essential tremors and degraded eyesight made hand lay out of the cam ID extremely frustrating, especially when it came to dividing the 180 degree, .250"R arc into 12 equal arc segments. Thinking I could draw this all day long in CAD I began to wonder if my little 10W laser would mark the steel. I put the HRS plate coated with blue layout dye on the laser and in a corner that would eventually become drop I ran the laser to scribe a 2mm circle. To my amazement the mark was crisp and clear against the layout dye. As glass is laser etched by first spraying the glass with black paint I assumed the layout dye was responsible for the effect on steel as well. Flipping the plate over I ground off the mill scale (which I hadn't done on the first side) and used layout dye. The marking now left by the laser was faint, barely visible. As it turned out the laser was etching the mill scale. I cut another plate, leaving the mill scale and using layout dye (for contrast) I got this result. Im moving forward again. FWIW.