@sqw
rough surface from the engrave.
Sounds like you should up your LPI setting. I use 270 on almost everything, but folks doing really fine stuff go into the 1000s.
If your engraving acrylic, try an unfocused engrave (Eg. on a 1/2" thick piece, set your manual focus to .01 - or on a 1/16" piece set it to .5)