Cpm-m4 hrc 64-65?

Joe Duder

Joe Duder

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Jan 22, 2013
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I'm new to the CPM super steel world, so bare down knife geniuses.

I'm looking to purchase a camp/utility blade. There's a 5/32" full convex CPM-M4 blade that I'm really interested in, but it has a HRC of 64-65. That seems a little high, but then again, I'm new to this game.
I'll be be using the blade for camping and hunting. It will see a lot of fish and game processing, feather sticking, whittling, chopping of small limbs no thicker than 1/2", food prep etc...

With these tasks being performed, how should this blade hold an edge/perform?

Is this steel hard to touch up in the field?

With that high of a HRC my guess is that I will experience some light chipping?

Any help would be appreciated.

Duder.
 
I have had no chipping or any other issues with CPM-M4. I only have one knife with it, the Spyderco Gayle Bradley, and have not had to sharpen it. It is a great steel.
 
The first question to answer your question is, what is the edge geometry like? How this was the edge ground before sharpening?
If the geometry is there to support that hardness you will have no problems. It will hold it's edge very nicely for a long time. However, if the geometry is too thin it will chip out till you remove enough of the edge to where the steel is present to support the really hard edge.
All this is not saying that the edge will be fragile. Everyone has a different idea of what hard use is.
I have had test knives that I beat for days and let someone else use it and they manage to wrinkle the edge.
I imagine that the knife will be able to take whatever you want to throw it at and turn around and smile at you.
 
Here's a pic of the blade and specs.
xkJTCia.jpg



Grind: Full Height Convex - Satin Finish
Edge: Convex (Polished and Stropped)
Steel: CPM-3V (0.145", 59-60 HRC with Cryo *)
Overall Length: 10.25”
Blade Length: 5.5"
Blade Height: 1.5"
Weight: 9.0
 
I just realized the pic is of cpm-3v. The m4 blade that I want is identical to this pic. But it's HRC is 64-65.
 
That point right where the satin bevel meets the polished edge is where the "magic" number lies, at least in the knives I make. If it is under say .018" I would say it is too thin edged for chopping and/or batoning.
 
You specs show a knife with 3V.

I have a 6-inch utility knife from Gilson that uses CPM M4 at 64-65 HRC. Yours looks like the same knife. It has a convex edge. The blade is 0.1425 inches thick, and the edge, where I chop, is 0.0330 inches.

When I first started chopping with it, the edge got some very small chips. I resharpened on a Worksharp because I didn't want to reprofile that kind of steel and I wanted to maintain the convex edge. With a convex edge, you really don't know what your getting because it could be convexed in a number of ways. I measure my convex edges with a laser protractor. I kept it at the 30 degrees inclusive (15 dps), and it handles light chopping without chipping. It's an awesome knife with great steel and a great heat treat.

Here's a chunk of sun-hardened Doug fir that I chopped just to test the edge. There was no edge damage.

DSC01991_zps98a3ae12.jpg
 
Twindog said:
You specs show a knife with 3V.

I have a 6-inch utility knife from Gilson that uses CPM M4 at 64-65 HRC. Yours looks like the same knife. It has a convex edge. The blade is 0.1425 inches thick, and the edge, where I chop, is 0.0330 inches.

When I first started chopping with it, the edge got some very small chips. I resharpened on a Worksharp because I didn't want to reprofile that kind of steel and I wanted to maintain the convex edge. With a convex edge, you really don't know what your getting because it could be convexed in a number of ways. I measure my convex edges with a laser protractor. I kept it at the 30 degrees inclusive (15 dps), and it handles light chopping without chipping. It's an awesome knife with great steel and a great heat treat.

Here's a chunk of sun-hardened Doug fir that I chopped just to test the edge. There was no edge damage.

DSC01991_zps98a3ae12.jpg
Click to expand...

That's the one I'm in the market for. So you just sharpened it? You didn't have to reprofile the blade?
 
Normally, I reprofile every new knife to a 30-degree inclusive V edge. I use the Wicked Edge with diamond stones. But with steel this hard, I didn't want to even attempt it. It would take way too long for my patience. And it came with a beautiful convex edge.

With the Worksharp (old model), it took just a minute to remove the chips and re-establish the same convex edge, and it has been good ever since.
 
I'm not an expert on the topic of steels and heat treat but I've been into knives a long time so just from experience and knowledge as an enthusiast I would recommend staying away from super hard super steels as a general use do it all camp/survival knife. I like a basic 1095 or similar steel for this purpose. I like the Ontario offerings but Becker and Esee are also great and proven choices. I've recently taken great interest in Randall Made knives and have my first arriving next month. I have spent many hours researching the history and build of Randall blades. Bo Randall wanted to build the most effective knife for use in the field so he kept the heat treat on the lower side by today's standards, sacrificing some edge holding to make sure the knife would not break and could be resharpened by the user. After many decades of building knives that have seen every environment known to man, I think he was right with his preferred choice of Swedish 01 tool steel at lower heat treat. Randall also uses a Stainless as an option on some knives but even the stainless is kept on the softer side by today's standards. Randall's experience and wisdom is something to consider when debating this topic.

Take Care.
 
Joe, that M4 blade is thick enough to handle what you throw at it. M4 is a great steel...of Gayle Bradley fame. And Sal Glesser runs his Spyderco Gayle Bradley M4 blades at 62-64 without a problem. That's one great folder. I've had five or six.

I just picked up a nice custom Kephart from Big Chris to handle duties similar to yours. My blade thickness and steel is lighter-duty than your choice, but my thinner 3/32" blade of O1 will be better for fishing duties, easier to sharpen in the field, but perhaps not as good for chopping. And, your M4 will hold an edge until the cows come home.
That 3V blade you showed earlier is as tough as a Navy Seal, can be darned near tied in knots without snapping, can chop all day without complaint, but will rust much more easily and won't hold an edge very long.
It's all "compromise."
 
Last edited:
precisionshootist said:
I'm not an expert on the topic of steels and heat treat but I've been into knives a long time so just from experience and knowledge as an enthusiast I would recommend staying away from super hard super steels as a general use do it all camp/survival knife. I like a basic 1095 or similar steel for this purpose. I like the Ontario offerings but Becker and Esee are also great and proven choices. I've recently taken great interest in Randall Made knives and have my first arriving next month. I have spent many hours researching the history and build of Randall blades. Bo Randall wanted to build the most effective knife for use in the field so he kept the heat treat on the lower side by today's standards, sacrificing some edge holding to make sure the knife would not break and could be resharpened by the user. After many decades of building knives that have seen every environment known to man, I think he was right with his preferred choice of Swedish 01 tool steel at lower heat treat. Randall also uses a Stainless as an option on some knives but even the stainless is kept on the softer side by today's standards. Randall's experience and wisdom is something to consider when debating this topic.

Take Care.
Click to expand...

Randall's knives are handsome and have been put to the test. But I can't see spending $600 for 1095 or 01. Just my opinion.
 
Joe, caught your comment..." I can't see spending $600 for 1095 or 01."

I suspect you need to talk to Big Chris....

IMO. :)
 
OP, I didn't mean to suggest going with a Randall. I was just saying this is what I've learned about the subject of hardness and steel selection when studying the history of Randall Made. For actual use, I would say a $70 Ontario or Becker or the like will be every bit as functional. Lastly, if you like the idea of Convex grinds you might take a look at Bark River or even Blackjack Classic blades. Most of them are A2 tool steel with full convex grinds and they come SHARP!!

keep us updated

Thanks
 
.03 is way to thick of an edge.

I personally don't see any advantage in M4 at that high and rc. Maybe just a personal preference.
 
Thanks for the recommendations Percision'. I'm trying to up my game and experience the super steels. I have a BRKT Aurora in CPM-3V and I really like it. Reading up on M4, I'm intrigued to say the least.
 
What I aim for in a good using camp knife in 3V is a edge thickness of .025" to .030" at roughly 1/16" from the apex of the edge. M4 will basically be able to handle most anything 3V can. If the thickness on the knife you want is roughly the same as what Twindog's knife is you are going to be fine.
I have a camp knife in PD 1 I just finished that is almost full convex ground with a 7.5" blade that is .020" thick .050" from the edge. This knife I heat treated to 63 Rc and have all the faith it it's ability to take abuse.
 
Joe Duder said:
Randall's knives are handsome and have been put to the test. But I can't see spending $600 for 1095 or 01. Just my opinion.
Click to expand...

1095 and O1 are better than CPM-M4 in many categories such as edge stability, toughness, sharpness and ease of sharpening.

I used to be "super steel junkie" and have used many exotic steel such as 3V, M4, S90V, M390, XHP, B75P, 10V, K390 and many more.

The most impressive steel I have been used is 52100 camp knife made by Burt Foster. Its hold and edge better than everything listed above except K390 while also much easier to sharpen and much stronger.
 
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