ZT691-SPI-TF 6,000 RPM Rated Large Cap. Composite Microstop Cage

Part Number: ZT691-SPI-TF

The ZT691-SPI-TF 6,000 RPM-rated, large capacity microstop cage, originally designed for composite work, is the ultimate microstop cage on the market for airframe work! Boeing and it’s subcontractors have standardized on this microstop cage for all of the new B787 program work. Here are a few of the features of this cage:


  • Fail-safe positive stop insures accurate repeatability and eliminates the possibility of work piece damage.
  • Felt dust shield eliminates composite/graphite dust contamination of the radial ball bearings extending cage life.
  • .0005″ incremental depth adjustment.
  • 1.250″ diameter cutter capacity with standard “SPI” style footpiece. For information on other footpieces see the “microstop cages & cutters” section of our website.
  • 7/16″ shaft travel with 3/8″-24 internally threaded shafts.
  • Shaft style is 3/8″ round with three flats.