SOLD CPM-M4 Gyuto 246mmx51mm (132grams)

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Full-time Knifemaker-Canadian Mazaki
KKF Sponsor
Feb 28, 2022
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Hello Everybody,

It's finally here, the first of three CPM-M4 knives to come. Not at all an everyday steel for a knife. I cannot over emphasize how difficult this stuff is to work with. I did 90% of the grinding before HT and still went through twice as many abrasive belts and sheets as I do grinding a 240mmx55mm AEB-L blade, on which I do 100% of the grinding after HT. Still, it was an interesting experience, and I'll know better what to expect next time around.

Simple burnt in fit using a dowel and epoxy, completely sealed at the end. I'm ashamed to say that the handle is a little out of square at the butt, and that the blade picked up a slight warp of about 1mm to the right, which I could not correct for the life of me. This blade also has a new grind that I'm experimenting with that begins back into the neck, rather than ahead of it, and has a slight right hand bias to its convexity.

For those of you who have never heard of CPM-M4 before, here's a link to a graph plotting the edge retention of multiple steels, including CPM-M4 to give you some idea about how it compares to many more commonplace cutlery steels. The graph however only shows CPM-M4 at 61 hrc, this knife being around 64hrc will perform even better, I suspect M4 at 64hrc would score between 600-625 TCC on a CATRA test.

  • Blade: 246mmx51mm CPM-M4 (64hrc) 320 grit hand finish
  • Neck: 20mmx21mm
  • Handle: 128mm, tapering from 23.9mmx20.8mm to 22.1mmx18.3mm, scorched oak, oiled and waxed
  • POB: 50mm from handle
  • Spine: 2.28mm at the neck, 1.40mm at 13cm, .88mm 1cm from the tip
  • Grind: flat to convex
  • Weight: 133 grams
  • Relieved choil and spine
  • Edge: .1mm


Asking $350 U.S, shipping included.


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Just to contribute to the record of this knife, here's a cutting video. The knife was taken to 2k on a diamond stone, deburred, and stropped. M4 is a toothy steel, comparable to 52100 in my estimation.

I just wanted to report, the packaging was great, shipping quick and the knife, well.....i am now a fan of m4. This is not a steel for the faint of heart or hand. The lightness is incredible and with a stiff spring flex, very even along the length. It may not be stainless, however a hot pork roast and a bath in hot coffee produced a 1/10 in blade discolouration. I was hoping for more vibrant blues, nope!! Duck’n fat, it’s toothy with fine bite. No problems with 2 stones(!not diamond) a 240 grit, chip remover and a washita(w/ atoma 400 slurry). About 50 strokes until decent bite. 200 for good measure. If a laser had an extreme, this would be it, my Nakiri is kinda envious of this thing. It killed a bag of potatoes for gnocchi and the leeks still diced with ease.
**Not a steel for beginner sharpeners, you will be crying after an hour of dullness.


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