940 Edge Rolling

Joined
Dec 11, 2013
Messages
72
First post!

I bought a 940 in Feb., my first one and I really like it. I bought it because I wanted a tough knife at work and thought that the blade shape would be up to whatever I threw at it.

I noticed yesterday that the edge seems to have rolled! I can't imagine how because I haven't hard used it yet. Just opening / breaking down boxes. Maybe I was expecting too much?

Has anyone else experienced this?
 
Need pictures before anything else. I can't say I've seen a lot of rolled S30V edges, especially as obtuse as the bevels are on Benchmade knives.
 
First post!

I bought a 940 in Feb., my first one and I really like it. I bought it because I wanted a tough knife at work and thought that the blade shape would be up to whatever I threw at it.

I noticed yesterday that the edge seems to have rolled! I can't imagine how because I haven't hard used it yet. Just opening / breaking down boxes. Maybe I was expecting too much?

Has anyone else experienced this?


The S30V steel on the 940 is a great steel...and it's overall performance is generally excellent, including its toughness. But regardless of the steel/maker/blade shape/etc., a knife will ultimately reach a point in which is needs to be resharpened...and some cutting activities are by nature going to cause more/faster edge deformation (dulling) than others. Cardboard is especially harsh on edges as are the things sometimes in the cardboard. Plus, if the factory edge wasn't quite as consistent as it could be, this could speed the process in which the edge itself deforms.

As you've gotten two months out of usage, even though light usage as you noted, the knife also may just need some light touchup. This need could be combined with the edge not being 100% from the factory, leading to it deforming at a faster rate than usual. The SharpMaker (and if you want a super sharp & enduring edge, a strop) will fix this quite quickly, and bring it to a degree of sharpness that exceeds the sharpness that most knives have at factory fresh edges.

I think if you take a SM to it and then strop it to get the edge to 'optimal health', you will probably see better performance in both how long the razor edge holds and how much the edge resists damage.
 
Need pictures before anything else. I can't say I've seen a lot of rolled S30V edges, especially as obtuse as the bevels are on Benchmade knives.

There were a few threads on USN dealing with rolled Sebenzas, so it seems to happen under hard use.
 
There were a few threads on USN dealing with rolled Sebenzas, so it seems to happen under hard use.

The Chris Reeve uses a lower Rockwell hardness than Benchmade, it's widely know as it's public information. It would be like comparing apples and pizza. What is a bit more strange is a single post indicating an issue, and no pictures or detail to provide evidence or information. One post wonders they are called.
 
The Chris Reeve uses a lower Rockwell hardness than Benchmade, it's widely know as it's public information. It would be like comparing apples and pizza. What is a bit more strange is a single post indicating an issue, and no pictures or detail to provide evidence or information. One post wonders they are called.

I agree with you, regarding the one post wonder. However, CRK hardens their knives to 58-59 RC, while Benchmade specs 58-60 RC. Unless it's public information that CRK doesn't treat their blades to the stated spec, only the highest hardness Benchmade blades will perform differently. Seems fairly apples to apples to me. :thumbup:
 
After 2 months of use, even medium use, on cardboard one might expect to have to touch up the edge. Probably just got a little dull and needs some TLC.
 
Sorry for the lack of pictures ... I'm without a camera at the moment. I use a sharpmaker on my knives. This is the first time this particular issue has happened to me. I did sharpen it at 30 deg. on the stones that came with it, which might be too accute without completely reprofiling the blade? Anyway, upon closer inspection it may have chipped rather than rolled... I can definetely feel it with my nail. I can get the blade sharp and it slices right through paper, but when it gets to the affected area you can feel it hang up.

It's not a huge deal as I bought the knife to beat on. I was just surprised it happened and wondered if anyone else had experienced something similar.
 
I agree with you, regarding the one post wonder. However, CRK hardens their knives to 58-59 RC, while Benchmade specs 58-60 RC. Unless it's public information that CRK doesn't treat their blades to the stated spec, only the highest hardness Benchmade blades will perform differently. Seems fairly apples to apples to me. :thumbup:
Someone on here sent their Sebenza blade to be Rockwell tested a few years back and I think it came in at around 58.5. The Benchmade S30V heat treat is about 1-1.5 points higher. That extra point really makes a huge difference in edge retention. While the 940 flat grind vs the Sebenza hollow grind makes the Sebenza much thinner behind the edge. I would expect the CRK would roll before the 940. I don't much understand why there is a 3 point spread in the Benchmade specs for this steel, and a 4 point spread on their D2. You'd think that higher end knife companies can zero in on their target hardness +/- 1 point.
/shrug
 
Sorry for the lack of pictures ... I'm without a camera at the moment. I use a sharpmaker on my knives. This is the first time this particular issue has happened to me. I did sharpen it at 30 deg. on the stones that came with it, which might be too accute without completely reprofiling the blade? Anyway, upon closer inspection it may have chipped rather than rolled... I can definetely feel it with my nail. I can get the blade sharp and it slices right through paper, but when it gets to the affected area you can feel it hang up.

It's not a huge deal as I bought the knife to beat on. I was just surprised it happened and wondered if anyone else had experienced something similar.

It's probable that 30º inclusive is too acute. I took mine to 15º per side with a micro-bevel of 17º per side. Takes care of chipping and rolling. My bet is that you chipped it instead of rolled it.
 
Revdevil: A 3-4 point margin of error is pretty common in rockwell testing, from what I have heard. Due to inherent variability in machine calibration, you are going to see a lot of variation in testing. A company that is providing an exact number are either giving an average or are BS-ing.
 
I agree with you, regarding the one post wonder. However, CRK hardens their knives to 58-59 RC, while Benchmade specs 58-60 RC. Unless it's public information that CRK doesn't treat their blades to the stated spec, only the highest hardness Benchmade blades will perform differently. Seems fairly apples to apples to me. :thumbup:

CRK's S30 and S35 steels are widely known to be relatively soft...it's a major reason so many people prefer the BG42 models and why some people even get the Seb blade treated by a third party. Even with the tougher S35VN (which some custom makers are hardening to 60-61 and finding it to be very tough for a stainless and reasonably easy to upkeep), CRK is still not hardening any higher...which I never understood because if one is going to pay for an expensive steel capable of high-performance, why not milk as much performance possible?




Sorry for the lack of pictures ... I'm without a camera at the moment. I use a sharpmaker on my knives. This is the first time this particular issue has happened to me. I did sharpen it at 30 deg. on the stones that came with it, which might be too accute without completely reprofiling the blade? Anyway, upon closer inspection it may have chipped rather than rolled... I can definetely feel it with my nail. I can get the blade sharp and it slices right through paper, but when it gets to the affected area you can feel it hang up.

It's not a huge deal as I bought the knife to beat on. I was just surprised it happened and wondered if anyone else had experienced something similar.

Which sharpener did you use?

S30V can sometimes chip, and although it's not common, it does happen. Depending on the condition of the edge from the factory, that could have increased the chance of it happening in certain usage situations, or even something that happened in transit or if a seller had it in a case in which it can make contact with other knife blades. Some freak thing like a hidden cardboard stable on a box could have even. So it's hard to say what.

Keeping the knife razor sharp on an angle confirmed as consistent and stropping can help slow/lessen the process in which edges become deformed/damaged...I think stropping makes a huge difference in both prolonging sharpness and lessening edge damage. And especially with S30V, I think stropping helps S30 hold its razor edge for much longer than just sharpening alone.

For actual treatment of this chip, a pic would be most helpful. More likely than not, sharpening using the same procedure/angle as if the chip was not there will sharpen the chip out as you remove metal.

Angle-wise, you'll probably find that there is a lot of personal preference between those who think using the factory angle is ideal versus completely reprofiling...there are pros and cons to each.
 
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