Answer
For CNC router marks, use 120 or 150 first, then 180 and 220 before finishing.
Why it happens
Toolpath lines need leveling with a grit that still cuts the ridges before finer prep.
Recommended grit
Use 120 or 150 for visible router marks, then 180 and 220 before finish.
Wet or dry
Dry.
Success check
Router lines are removed and the surface has an even scratch pattern.
What to do
- Clean dust from the machined surface.
- Sand visible toolpath lines with 120 or 150.
- Refine with 180.
- Finish prep with 220.
Avoid: Do not jump straight to fine grit while toolpath ridges remain.