The first attempts using variable power engraves @100% fractured like you mention, leaving sharp edges on the bottom of the piece and an uneven engrave. Switched up my settings to use the dot pattern @ full power for 3 passes and masking the piece before engraving and I’m loving the results! The engrave isn’t as deep but it’s infinitely more desirable.
Found this thread that has similar settings for those exploring…
https://community.glowforge.com/t/salt-shaker-settings/10146