SOLD 270mm CPM-M4 HSS Sujihiki (Semi Custom)

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MSicardCutlery

Full-time Knifemaker-Canadian Mazaki
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Hello All,

Here I have an absolute monster that I've been plugging away at here and there for a few months; a thicker suji in CPM-M4. This steel is an absolute beast to work with, but it takes a very resilient, long lasting and toothy edge. In the high alloy steels I've used, M4 feels the prickliest. One of our members here has a couple of gyutos in M4 I made some months ago, and uses them at work daily. He tells me they need touching up between once a month and once every 6 weeks. Which to my ear, is just remarkable, considering that even the best low alloy knives seldom make it more than 3-4 shifts between touch ups.

This type of steel, while extremely difficult to work with, produces an excellent blade which will exceed expectations. I should also mention that M4 is fairly non reactive for a non stainless steel. Coffee etching has little effect on it, and it patinas very slowly in use. Have a good Saturday!



  • Blade: 270mmx39mm CPM-M4 (64 HRC) Med. Scotchbrite belt finish.
  • Neck: 17mmX???
  • Handle: TBD
  • POB: TBD
  • Spine: 3.41mm at the neck, 2.86mm at halfway, .88mm 1cm from the tip
  • Grind: flat to convex RH bias
  • Weight: TBD
  • Relieved choil and spine
  • Edge: .1mm, .28mm @2mm, .71mm@5mm, 1.16mm@10mm measured at the midpoint.
Base price (for a plain burned oak handle) $375 U.S shipped with insurance anywhere in North America, for shipping to Europe or Australia I will cover the first $32 U.S of shipping.
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props! i love reading your posts and seeing your knives.

In the high alloy steels I've used, M4 feels the prickliest.
...
This type of steel, while extremely difficult to work with, produces an excellent blade which will exceed expectations.

curious about this vs something like magnacut. i know many steels are "up there", but do you think the hardness/HT of this sample made it harder to grind?
 
props! i love reading your posts and seeing your knives.



curious about this vs something like magnacut. i know many steels are "up there", but do you think the hardness/HT of this sample made it harder to grind?

Thanks!


And....hm.....well, I'll put it this way...with regards to grinding, M4 makes MagnaCut look.....cute. There's no doubt between the two that M4 is much harder to grind. It's just brutal. I can still use belts that will not cut M4 to grind hardened AEB-L and 52100. Now it's worth mentioning that my M4 is usually in the 64-65hrc while my MagnaCut is in the 63-64hrc range, which isn't a huge difference, but it isn't a direct comparison of the steels at the same hardness. According to Larrin's CATRA chart, M4 has about the same edge retention at 61hrc that MagnaCut does at 65hrc. Roughly estimating for my own hardnesses, my M4 will probably have about 12%-13% greater edge retention than my MagnaCut, as far as the chart is concerned.

Where M4 really stands out to me, is the feel of the edge. It's as prickly as any low alloy carbon steel, and it's really easy to form a nice edge on, provided you have the right stones. It doesn't really fight you, it's one of those steels that just feels like it wants to get screaming sharp. It deburrs very easily. It's insanely tough too. I dropped my first M4 gyuto on my shop floor while I was finishing up the grinding on it, heel first too. The heel was a little dusty, but there was a chip in the concrete.
 
Thanks!


And....hm.....well, I'll put it this way...with regards to grinding, M4 makes MagnaCut look.....cute. There's no doubt between the two that M4 is much harder to grind. It's just brutal. I can still use belts that will not cut M4 to grind hardened AEB-L and 52100. Now it's worth mentioning that my M4 is usually in the 64-65hrc while my MagnaCut is in the 63-64hrc range, which isn't a huge difference, but it isn't a direct comparison of the steels at the same hardness. According to Larrin's CATRA chart, M4 has about the same edge retention at 61hrc that MagnaCut does at 65hrc. Roughly estimating for my own hardnesses, my M4 will probably have about 12%-13% greater edge retention than my MagnaCut, as far as the chart is concerned.

Where M4 really stands out to me, is the feel of the edge. It's as prickly as any low alloy carbon steel, and it's really easy to form a nice edge on, provided you have the right stones. It doesn't really fight you, it's one of those steels that just feels like it wants to get screaming sharp. It deburrs very easily. It's insanely tough too. I dropped my first M4 gyuto on my shop floor while I was finishing up the grinding on it, heel first too. The heel was a little dusty, but there was a chip in the concrete.

Definitely can relate to that. I did one blade in m4 a few years ago and i remember that even with new fresh ceramic belts the steel felt like it wasant moving at all, if i remember well it took about 6 belts to get the knife partially ground even when it had only 2mm thick.

Insane steel, whoever take this knife will definitely be pleased on its performance. GLWS
 
M4 is big in the competition chopper world. Anyone who's seen what those dudes put a blade through is usually pretty impressed.
I have some 5mm stuff I intended to use for choppers at one point....the bar may just turn into WH ground gyuto now though. Just hard to motivate myself to do that much grinding. Even annealed the stuff grinds like hardened 5160.
 
I have some 5mm stuff I intended to use for choppers at one point....the bar may just turn into WH ground gyuto now though. Just hard to motivate myself to do that much grinding. Even annealed the stuff grinds like hardened 5160.

Some time ago, Shawn Houston put up a video showing all the consumables that go into making these high carbide steels and the volume and expense of the abrasives was crazy. Not to mention, like you say, the time.

There's definitely a reason why some steels cost the customer more than others!
 
Some time ago, Shawn Houston put up a video showing all the consumables that go into making these high carbide steels and the volume and expense of the abrasives was crazy. Not to mention, like you say, the time.

There's definitely a reason why some steels cost the customer more than others!
Oh the consumable cost is definitely up there. I can probably make 3 240mmX55mm gyuto from AEB-L with the same number of belts it take to make one 240mmX50mm in CPM-M4. I do want to play with high wearing steels a bit in the new year though....I've had my eye on S90V for a while...10V too
 
Hello All,

Here I have an absolute monster that I've been plugging away at here and there for a few months; a thicker suji in CPM-M4. This steel is an absolute beast to work with, but it takes a very resilient, long lasting and toothy edge. In the high alloy steels I've used, M4 feels the prickliest. One of our members here has a couple of gyutos in M4 I made some months ago, and uses them at work daily. He tells me they need touching up between once a month and once every 6 weeks. Which to my ear, is just remarkable, considering that even the best low alloy knives seldom make it more than 3-4 shifts between touch ups.

This type of steel, while extremely difficult to work with, produces an excellent blade which will exceed expectations. I should also mention that M4 is fairly non reactive for a non stainless steel. Coffee etching has little effect on it, and it patinas very slowly in use. Have a good Saturday!



  • Blade: 270mmx39mm CPM-M4 (64 HRC) Med. Scotchbrite belt finish.
  • Neck: 17mmX???
  • Handle: TBD
  • POB: TBD
  • Spine: 3.41mm at the neck, 2.86mm at halfway, .88mm 1cm from the tip
  • Grind: flat to convex RH bias
  • Weight: TBD
  • Relieved choil and spine
  • Edge: .1mm, .28mm @2mm, .71mm@5mm, 1.16mm@10mm measured at the midpoint.
Base price (for a plain burned oak handle) $375 U.S shipped with insurance anywhere in North America, for shipping to Europe or Australia I will cover the first $32 U.S of shipping.
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View attachment 214605

Edge geometry on this:

0ff49113f737f6725161e579f345863f0a8b6d82d260aca7a3726c18b760b024_remastered.jpg
 
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