Years ago i modified this Spyderco Endura ZDP-189 from a saber/flat ground to a saber/hollow ground knife with the help of my trusted Tormek T7 fitted with an SB-250 Black Silicon stone & a modified knife clamp.
Previously the knife looked like this (with an already Tormek reprofiled edge angle of ~25 degrees inclusive)
(https://i.postimg.cc/wjBNr6P9/image.png) (https://postimg.cc/bsKdDjp5)
(https://i.postimg.cc/L8sPWH7M/image-(1).png) (https://postimg.cc/4mrn7Ts8)
(https://i.postimg.cc/kXs8wVjP/image-(2).png) (https://postimg.cc/mtctgrfm)
Afterwards the knife looked like this.
Although the edge angle was only marginally thinned to ~22,5 degrees inclusive, the area just behind the edge is much thinner now at ~0.3 mm, making the the knife cut better noticeably.
(https://i.postimg.cc/FspcGfPm/image-(3).png) (https://postimg.cc/crKrLJy5)
(https://i.postimg.cc/VLmnj9WB/image-(4).png) (https://postimg.cc/F1CYvLq7)
(https://i.postimg.cc/YqMY1NzY/image-(5).png) (https://postimg.cc/4n2YG9Mx)
(https://i.postimg.cc/sDs7pP4G/image-(6).png) (https://postimg.cc/JtYs8kgR)
(https://i.postimg.cc/9FCZGPYr/image-(7).png) (https://postimg.cc/vD24yVjs)
(https://i.postimg.cc/VsjXrZnf/image-(8).png) (https://postimg.cc/dDVhgB5p)
The job took about 2 hours of grinding (with the SB-250 stone graded to coarse with the help of the TT-50 diamond stone grader), as ZDP-189 in it's hardened state (64-65 HRC on this model) is quite some wear resistant stuff.
To grade it back to fine (for normal sharpening) i use a large diamond stone, as the standard SP-250 grading stone is completely useless on the silicon carbide stone.
For this project i ran my SB-250 in a trough completely filled with a Windex clone to avoid glazing the surface during grinding & sharpening.
The knife is on a more or less permanent loan with a friend of mine who works as a process operator in a baby milk plant, where part of his job is cutting open huge plastic bags (with glued cardboard top layer and about the size of a small room) containing milk powder.
The wear & tear resistant plastic plus the industrial type of cardboard in those bags ruin edges in no-time, and so far this reground ZDP-189 Endura lasts the longest from all the knives used in the plant, also because of those serrations which enable him to get the job done when the plain edge part gets too dull.