The KNIFE (Part 4021900100) is a genuine JACK original replacement part designed for JACK JK-780, JK-781, JK-782 and JK-783 SPEEDWAY SW 781D series walking foot machines. Manufactured to OEM specifications for precise fit and reliable performance.
Equivalent Part Numbers
JACK: 4021900100
Compatible Machines
This part fits the following industrial sewing machine models:
Looking for a replacement knife for your JACK JK-780 or JK-781 walking foot machine? This genuine OEM part ensures reliable performance and precise fit. Shop with confidence — all parts ship from Miami, FL.
⚠️ Compatibility Notice: Always verify your machine model and subclass number before ordering. Part numbers and compatibility are provided as a reference only. Supra Sewing is not responsible for purchases made without confirming compatibility with your specific machine. All sales on replacement parts are final.
