I was playing around with my toy USB microscope, looking at the details of engraves done with my GF (and admiring how nicely tiny text comes out!), and noticed something interesting. I did an engrave of some text (as a vector engrave) into the Medium Maple Hardwood; here’s a letter “m” that was part of it:
Probably looks very standard to everyone here. But I’d noticed during engraves that the “wall” of parts of letters was light. Well, when I tipped the board to look down at the walls of the engraves, I noticed that the the “sides” (those faces perpendicular to the direction of travel of the laser) and the “bottom” (the part of the text that is where the engrave starts, which of course is normally the bottom of the text) were the dark brown (I assume it’s charred wood). But the “top” (the wall at the top of the text, where the engrave ended) was not. Here’s a picture of the bottom of the “m” :
And here’s a picture of the top:
And just to clarify, the laser head was moving left to right back and forth for each pass, and each successive line of the engraving run went progressively up.
Now, I understand why burn marks on the masking paper for PG materials seems to have a directionality to it – the airflow from the fan presumably blows the smoke in one direction. But it’s not obvious to me why the top/end of an engrave would look different than the bottom/start. I guess there’s a chance that the wood was not perfectly flat, and/or the laser beam is angled a bit, but I don’t think even that would explain it.
Any ideas what would cause this difference?
(Also, Happy New Year!)