Is M4 Really That Tough?

S

Sharperthansticks

Joined
Sep 19, 2017
Messages
1,612
I use my Manix 2 in M4 to cut down Costco boxes, and after one or two boxes (where, admittedly, the corners can be tough with multiple, thick plies of cardboard), I have nicks in my blade that I can see when I shine a light on the blade edge. Is M4 really that tough?
 
Sharperthansticks said:
I use my Manix 2 in M4 to cut down Costco boxes, and after one or two boxes (where, admittedly, the corners can be tough with multiple, thick plies of cardboard), I have nicks in my blade that I can see when I shine a light on the blade edge. Is M4 really that tough?
Click to expand...
No. It's relatively tough considering how hard it gets. It's not really tough in absolute terms.
 
You might have gotten a bad one. NickShabazz NickShabazz reported an issue with an M4 blade a while back, Spyderco exchanged it and it was really good. I believe he reported basically the same thing where it was really bad after cardboard cutting.
 
b00n said:
You might have gotten a bad one. NickShabazz NickShabazz reported an issue with an M4 blade a while back, Spyderco exchanged it and it was really good. I believe he reported basically the same thing where it was really bad after cardboard cutting.
Click to expand...
Wow. That's really good to know. Nick makes a big deal about how friggin' tough it is, so I was surprised when the blade nicked so easily.
 
I use one of my GB2 pretty hard and also got tiny nicks. I find it’s pretty tough, but it also shows small nicks sometimes.

I kind of equate this to the thin geometry more than anything. 1095 ground that thin would show deflection (not a nick but damage nonetheless).

In my experience CPM M4 is a pretty tough steel that sharpens pretty easily and takes a beautiful crisp edge.
 
I don't know if it's a deflected edge or a ruptured edge; regardless, after breaking down a box, I look at the edge under lamp light, and there are clearly several spots where the edge is not intact, and when I run the blade through fine, floppy paper that advertisers send out, the blade snags just a bit. I'm running a 17 degree angle on the M4 Manix. I was under the impression from Nick and others that that blade could take much more than I'm throwing at it before visible edge imperfections show up. (The sharpenability isn't the question, so I left that piece alone.)
 
MolokaiRider said:
Try giving it a good sharpening and see if it happens again.

It’s possible the factory edge got a bit too hot.

If you do, could you share if it improved your edge integrity?
Click to expand...
I sharpened it recently and got it shaving sharp with a 12,000 grit belt (WSKTO + blade grinder), followed by the WSKTO stropping kit, where I used the green compound, not the red. After this, I tested the sharpness, and I could easily get through floppy paper without needing to start slowly right next to the paper. Then I cut down a Costco box and now I have edge deformities again. Sure, I can sharpen them out again, but the whole purpose of M4 is not needing to do that (so quickly).
 
Sharperthansticks said:
I sharpened it recently and got it shaving sharp with a 12,000 grit belt (WSKTO + blade grinder), followed by the WSKTO stropping kit, where I used the green compound, not the red. After this, I tested the sharpness, and I could easily get through floppy paper without needing to start slowly right next to the paper. Then I cut down a Costco box and now I have edge deformities again. Sure, I can sharpen them out again, but the whole purpose of M4 is not needing to do that (so quickly).
Click to expand...

Well it certainly sounds like you can rule out a weak factory edge. I have never used a Work Sharp, so I’m assuming it doesn’t run fast enough to burn the edge.

I agree it sounds like you should not have nicks after cutting a couple of cardboard boxes.
 
[Qgot aOTE="Sharperthansticks, post: 18602969, member: 484261"]I use my Manix 2 in M4 to cut down Costco boxes, and after one or two boxes (where, admittedly, the corners can be tough with multiple, thick plies of cardboard), I have nicks in my blade that I can see when I shine a light on the blade edge. Is M4 really that tough?[/QUOTE]
I got a GB1 with a bad heat treat.Cut a few boxes and back to not very sharp.Sent back to Spyderco and they sent me a new one. Now M4 is one of my favorite steels.Cuts for day's. Bench made has the best M4 . In my opinion.
 
I've used M4 a lot over the last few years. Although I have had chipping at times, it's been tough enough for my needs at work. In my personal experience, the beauty of M4 is being able to take the edge down pretty thin and still be able to cut without any major damage. YMMV. I'm using Spyderco's M4 by the way.
 
Sounds pretty obvious that you should send it back to Spyderco and they'll make it right.

It sucks, but that's why we all have "back-up knives", right? ;)
 
I EDC a Gayle Bradley 1 and have never experienced Chipping. Of course this is a different knife, maybe made in a different factory. I use around the shop, yard, and house and other than an occasional sharpening have never had any issues, knock on wood. I'm wondering when you were chopping up boxes if you hit a large staple of some sort. I have never experienced problems with big boxes, appliance boxes, toilet boxes, etc.
 
Last edited:
Any steel will deform when it hits something harder, like grit embedded in cardboard (silicon is hard stuff), staples, etc. I prefer an Olfa boxcutter rather than sacrifice my good knives.
 
I cut through what I thought was a plastic cord for hanging a sign with my GB1, turns out it was about 1.5mm thick steel core, it dulled it a little, but no edge damage at all. I will say though, that with cardboard- most is recycled and lots of recycled paper includes staples still holding it together so that along with dirt/sand whatever else gets ground up and pressed into new cardboard, I've used knives on cardboard all day- sharpen it up at home and start the next day and get a ding in the edge immediately from cutting a box from the same stack of cardboard I was working on the day before.
 
Thanks for all the input, everyone. Like I said, I'm going to send (actually, by now, I've already sent) the knife back to Spyderco. (This was a good time, anyway, since I have a Stretch 2 with really gritty action, even after I disassembled it, cleaned it, lubed it, and reassembled it, because I couldn't quite get it back together perfectly, due to some slight mismatch of scale and liner. So, I sent both the Stretch 2 and the Manix 2 together for a ride to Colorado.)

There is one item I forgot to mention, and when I realized it, I felt pretty stupid; hopefully this will not cause a pile-on: I'm breaking down the boxes on to a piece of wood, so the knife's motion terminates as it hits the wood as opposed to terminating in the air. I do not know the composition of the wood, as it was a scrap that I got for free from Home Depot, which I varnished and affixed to my table to use as a work bench. (This is the advantage of being a man living alone; there's no woman to object to my using my kitchen table as both an eating surface on the one hand, and a full workbench with Dremel, table vise, and belt sharpener, on the other.) It is possible that hitting the wood is the issue. The one thing I can say about the wood is that the cross section shows that it is in plies, so that probably rules out a hardwood; I am thinking that this is pine.
 
I think it’s more in relative terms, for a steel that holds a 60+ HRC at 1500F it has high toughness, also in comparison to other HSS like maxamet, Rex121, HAP72 etc it’s very tough.
 
b00n said:
You might have gotten a bad one. NickShabazz NickShabazz reported an issue with an M4 blade a while back, Spyderco exchanged it and it was really good. I believe he reported basically the same thing where it was really bad after cardboard cutting.
Click to expand...

Hi, sorry I'm late here, but this is incorrect. The issue I had was with Maxamet, a first-run Native. M4 has been nothing but magical for me.
 
You must log in or register to reply here.
Back
Top