Font Issue, Vertical lines?

I am now getting horizontal lines through my letters when view/cut in Lightburn?

I am using Makerspace laser machine, I believe it is 80 watt…

Fills are generated using horizontal lines spaced closely together, so it’s not surprising you can see them in the preview, especially if you zoom in.

You can make the spacing tighter by increasing the “lines per inch” value or decreasing the “interval” - 0.1mm interval is 254 lines per inch. For smaller text, I often use 0.08mm / 318 DPI, or sometimes go as far as 0.05mm / 508 LPI.