Check filament for defects

thingiverse

To quickly detect thin defects in a spool of filament, set your caliper to the minimum acceptable thickness and tighten its screw. Clamp the caliper horizontally to a rigid surface and thread the filament end through its jaws. Run the filament from the full reel to an empty one; if it's thinner than the set width at any point, it will either catch in the jaws or fall out completely. Mark bad sections with masking tape, adjust as needed, and continue reeling until finished. This method took about an hour for two spools and could be developed into a real project.