Laser Experiment: Spline Spiros and Balsa

I've been poking around in Inkscape some more and decided I had to give spline spiros a shot, because they are somewhat cool, and make the creation of neat filigree stuff much easier. I put together a simple design roughly 2.75" wide by 5" long or so. I wanted to engrave it into some very thin balsa wood I had, 1/16th of an inch thick.

This balsa wood is probably the thinnest and most flimsy wood I have attempted to work with in the laser so far. But it's cool because it happens to be somewhat transmissive of light, which got me thinking about the possibilities. It's not as temperamental as neoprene or paper, but it took a little bit to get it right. My intent was to engrave fairly deep, to about half the depth of the wood, so that when it is illuminated from behind the pattern will be visible.

I started at 20% power, and found it didn't do much besides discolor the wood. Then I moved up to 50% power and found it was making a good amount of soot, and actually pierced through the wood in some places. It was also producing enough localized heating to warp the wood slightly, which is why it appears pierced more in the center of the design than the edges.

I finally settled on about 30% power as the ideal balance.