CPM 20CV — rolling

It's also common for production knives like that to be overheated while they are sharpened on belt grinders at the factory. The steel may have been slightly softer because of that. Be happy it was just a roll, be aware that it's a common problem with thin tips like that, sharpen it out and enjoy your knife.
 
I dropped my ZT 0562 to the hard wood floor. The knife was closed but the edge bevel near the tip sheared off. Only way j can describe it. Took a little elbow grease on the diamond stone but I got it back close to factory I think.
 
mmyron1 said:
I dropped my ZT 0562 to the hard wood floor. The knife was closed but the edge bevel near the tip sheared off. Only way j can describe it. Took a little elbow grease on the diamond stone but I got it back close to factory I think.
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Sorry to hear that, but at least you got it back to factory. Is that in 20CV or S35VN?
 
This can happen. Countertops, plates, etc. can be very hard. It could have gotten bumped casually, went through the box just right at a seam, etc. Trace the line of the bend and realize just how thin a cross section of blade that is. Also consider that the steel along factory edges can sometimes be a little fatigued by the grinding process and not representative of the true quality you'll get after putting a few fresh edges on it.

Once you've sharpened past that by hand, I'd expect your overall edge retention to improve here too.
 
Chronovore said:
This can happen. Countertops, plates, etc. can be very hard. It could have gotten bumped casually, went through the box just right at a seam, etc. Trace the line of the bend and realize just how thin a cross section of blade that is. Also consider that the steel along factory edges can sometimes be a little fatigued by the grinding process and not representative of the true quality you'll get after putting a few fresh edges on it.

Once you've sharpened past that by hand, I'd expect your overall edge retention to improve here too.
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Thanks for your great input. I'm learning a lot here. It makes sense that the factory edges are a little fatigued after the grinding process. Once it's ready for a resharpening I think I can get the folded steel/rolling out.
 
TBH most of my new knives experience chipping or rolling, from S110V to 1095. I equate it to power tools being used at the factory. After a good session on stones the issue usually is allieviated.

It sort of reaffirms my preference to use a blade prior to going camping or on an adventure to address these issues.
 
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MolokaiRider said:
TBH most of my new knives experience chipping or rolling, from S110V to 1095. I equate it to power tools being used at the factory. After a good session on stones the issue usually is allieviated.

It sort of reaffirms my preference to use a blade prior to going camping or on an adventure to address these issues.
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A little off topic, but do you think a blade that is re-sharpened on a WorkSharp system won’t hold an edge as long as if it were sharpened on stones?
 
tony281sc2 said:
A little off topic, but do you think a blade that is re-sharpened on a WorkSharp system won’t hold an edge as long as if it were sharpened on stones?
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That's a great question, and one I could not answer as I don't have one.

I am purely speculating, but I often wonder if blades being sharpened at a factory are just rushed through.

Burrs, burnt edges, or steel that is too thin for its hardness.

Or maybe the blades are not being kept cool enough. It's also possible the steel type is experiencing carbide tear-out.

Old belts vs new belts. Heat treating might be an issue.

There are a lot of variables that I can't quantify.

From my understanding the KOWS spins pretty slow, which is a positive.

Years ago, I used to sharpen my big blades and machetes on a grinding wheel. That was a big mistake, as my edges would always crumble. Way too aggressive and hot.

All that I do know, is that many of the knives I get have an edge that will chip and roll. This seems to lessen considerably after hand sharpening.
 
Jay2021 said:
OK, thanks for your input. I'll sharpen it up. The knife barely tapped the bottom of the pastry box, which is why I was so surprised that the tip dulled. It really took just the tiniest of taps. It's a Hogue Deka. Great knife, I recommend it. Just don't go cutting up any almond brittle.
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Hmmm...thanks for the heads-up. I just got one of those. (birthday gift a couple of weeks ago.)
With the .095" blade thickness, I didn't figure it for a hard use knife, but I'll exercise additional caution.

It is a very nice knife, though. Almost a gentleman's knife. (Which, as an engineer, I kind of don't qualify for.)
 
Looks like an over heated tip from power factory sharpening or you hit the counter underneath and don’t know it.
 
me2 said:
Looks like an over heated tip from power factory sharpening or you hit the counter underneath and don’t know it.
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Thanks for your input--much appreciated. Chances are it tapped the counter underneath without me recognizing it at the time. Otherwise, how exactly would an overheated tip lead to rolling? Would this make the tip harder/softer? Just curious.
 
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tony281sc2 said:
A little off topic, but do you think a blade that is re-sharpened on a WorkSharp system won’t hold an edge as long as if it were sharpened on stones?
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A guy on Youtube actually did a cut test comparing two of the same knives sharpened to the same level (BESS tested), one on stones and another on the Ken Onion Grinder. The Work Sharp knife performed a little better, surprisingly. Small sample size, and the difference wasn't significant, but reassuring if you're using that system.


 
Jay2021 said:
Thanks for your input--much appreciated. Chances are it tapped the counter underneath without me recognizing it at the time. Otherwise, how exactly would an overheated tip lead to rolling? Would this make the tip harder/softer? Just curious.
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The steel in your blade is heat-treated to have specific properties. Grinding dry with a power tool can sometimes create high heat right at the surface. It can be enough to diminish those properties right at the surface.

I don't know enough to say why this tends to happen at the factory grinder but not so much with home systems. I just know that it happens. This is why some people in this thread have reported issues with factory edges that tend to go away after sharpening past that surface layer. This is also part of why edge retention results tend to pick up with subsequent edges in controlled cut testing.
 
Chronovore said:
This is also part of why edge retention results tend to pick up with subsequent edges in controlled cut testing.
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Another reason is because the grind angle becomes for obtuse with subsequent sharpening. That alone will lead to better edge retention, as the edge gets more meat behind it with every sharpening. (Assuming you don't purposely thin the edge out to compensate.)
 
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