Cpm-m4 556 - Update - Broken Spring.

richstag said:
Does anyone know what temperature CPM-M4 has to reach before the heat treat is ruined?
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This is not going to be much help, but...I had ventured a WAG at Spyderco Forums on that topic and was corrected by Cliff Stamp. In a nutshell, you can't judge by the temperature of the blade itself because it acts as a heatsink...the question that matters is temp at the edge, and Cliff's answer was that it is surprisingly easy to anneal the edge itself without even realizing what you're doing.

I don't remember the temps that were being discussed, nor do I remember how they were being generated, sorry. :o You could search over there...
 
Thanks, and I agree with Cliff 100 percent. I am not worried for grinding issues. I sharpen free hand on stones so its not an issue. I was wondering for a different set of reasons. Thanks for the effort :)


JNewell said:
This is not going to be much help, but...I had ventured a WAG at Spyderco Forums on that topic and was corrected by Cliff Stamp. In a nutshell, you can't judge by the temperature of the blade itself because it acts as a heatsink...the question that matters is temp at the edge, and Cliff's answer was that it is surprisingly easy to anneal the edge itself without even realizing what you're doing.

I don't remember the temps that were being discussed, nor do I remember how they were being generated, sorry. :o You could search over there...
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I have sharpened free hand on stones for quite a few years now so I am not sure what angle I put on this knife. When I get a new steel I always sharpen it so I can use it but I will slowly lower the edge at each sharpening. That way I can ease into testing the limits. With this CPM-M4 I now have the edge set with the thumb studs just a HAIR off the stone. I have no clue what this angle is but the edge is holding amazingly. Just thought I would post my feedback on this. Maybe someone that knows how to figure it out can tell the angle from the edge to the thumb studs? Anyhow, no microbevel on the edge and it still holds strong. Really liking this knife more and more.

Kevin
 
When you say right outside, you talking East of 235, closer to the base? Or on out Hermanvile? Feel free to contact message instead of posting here if you like.
 
The pivot screw finally worked itself loose so I took it out, cleaned it and put a piece of teflon tape around the threads. Tightened it back down where I want it and seeing how well it holds. The teflon tape is a trick I learned carrying Emerson knives and it always worked with them. No mess of locktite and if you put it on right it never has to be replaced during future dis-assembly.

Kevin
 
HEY, that's a great idea! I had never thought of that.
I got tired of the mess with loctite. Lately, I've been running a small bead (with a toothpick) of superglue around the head of the screw. It glues it to the g10, and I've never had one come loose after that. If you're careful, you can't even tell it is there. And if it comes time for disassembly, it breaks loose pretty easily, with the small bead. Sometimes I screw up and it gets a little messy, but hey, all my knives are users, so I don't worry about it. As long as it works.
 
Just a couple more cell pics for the thread. Loving the steel but hating the rust. Still baffled on how this etching is reacting. The edge sure will not rust. I have tried some pretty hardcore rust preventatives at this point too.



Pocket clip wearing in



Kevin
 
It has been about three weeks using and abusing this knife and I have come to a pretty decent conclusion. Using this knife for anything and everything has really given me a great perspective on it. My conclusion is I love this knife overall. I have not liked a modern knife as much as this one is a very long time if ever. All for a bargain price IMHO.

I hope to update this thread as time goes on but for now I am putting up my thoughts after the three week torture testing.

Kevin
 
I've had the edge rust a bit on mine. However I used it hard, got it wet (not just water) and didn't clean it. So not surprising really.
 
richstag said:
Yeah man! I have been using it for floor tiling jobs this week. Huge commercial jobs. This thing has taken a serious beating and its just performing so well.
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Seriously, it's too bad it took Benchmade so long to notch up their HT on M4. They really had M2 cranked. When they switched to M4 they ran it on the soft side for quite a few years. The new blades are great stuff.
 
I don't know much about CPM-M4 aside from my use with this knife. As far as I'm concerned it's not too hard in any way. I have not had a single chip out of the blade. Even hitting vinyl tile (which is actually awful on a blade) the edge did not chip. I got a little rolling but that's it. You would not believe what this knife has been through and I have only had to sharpen it three times. It needs to be sharpened now to get a couple rolls out near the tip but it's still sharp. I just like my knives to be insanely sharp. Most average users would consider it to be very sharp still.

Kevin
 
richstag said:
I don't know much about CPM-M4 aside from my use with this knife. As far as I'm concerned it's not too hard in any way. I have not had a single chip out of the blade. Even hitting vinyl tile (which is actually awful on a blade) the edge did not chip. I got a little rolling but that's it. You would not believe what this knife has been through and I have only had to sharpen it three times. It needs to be sharpened now to get a couple rolls out near the tip but it's still sharp. I just like my knives to be insanely sharp. Most average users would consider it to be very sharp still.

Kevin
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The RC hardness of any blade steel is important..these are 62-64HRC which is pretty hard..about right IMO...
 
Historically, BM ran it a lot softer. Without digging out the old catalogs, I think it was 58-60 or 59-61 Rc. 62-64 Rc is almost a different steel. :thumbup:
 
Honestly the 62-64 is why I jumped on this knife. It seems across the board Benchmade takes its numbers a littler higher than some other companies. That is part of the reason I am carrying a Benchmade vs a CRK or EKI.

On my comment regarding too hard for CPM-M4 I was actually curious more of the limits. Anyhow, I wish Benchmade would put out more knives with this steel and the new hardness. I would be very interested.

Kevin

JNewell said:
Historically, BM ran it a lot softer. Without digging out the old catalogs, I think it was 58-60 or 59-61 Rc. 62-64 Rc is almost a different steel. :thumbup:
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I figured I would throw in a few cell pics over time showing the progression of this knife.







At this point I am actually sharpening lower than the thumbstuds.

Kevin
 
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