I am a hobbyist experienced in model rocketry, but am a complete newbie to lasercutting/engraving. I purchased the Ortur Laser Master 2 Pro S2, and I am basically trying to laser cut fins and centering rings for mid/high power rockets using baltic birch plywood (1/8" - 3mm thickness). I am also a newbie to Lightburn and am learning things as I go, but am having difficulties getting simple things like circles (centering rings) to come out perfect - they either seem to be a slight oval/not completely perfect, and when cutting long straight lines, the Ortur LM2 is giving me an error 18 - flame detected - even though there is no flame (using air assist), which seems to be easy to bypass by hitting the power button.