Lower Blade for Cut and Sew / Overlock (Ref. A10531000)

Maintaining the cutting system is the key to professional overlock stitching. This is the lower blade (fixed knife) that works in conjunction with the moving upper blade to trim excess fabric as the machine finishes the edge of the seam.
When the machine starts to push or "chew" thicker fabrics instead of cutting them cleanly, the cause is often a blunt lower knife. A lower blade worn or damaged by pins will also ruin the cutting edge of a new upper knife in a few minutes, requiring the replacement of the complete pair to restore factory performance.
(Original reference and equivalents: A10531000)