CPM Cruwear chipping?

[Bemo]

I don't get this automatic default to "burnt edges" . We know the sharpening is done in a way that prevents it. I'd really like to see some proof that Spyderco has burnt edges. Sure I know in theory it can be possible with some sharpening jobs somewhere. I've seen it on one new knife in my 50 years of knife use and it was discolored and very apparent. It was an exceedingly thin knife made by a well known maker in Japan done with "R2" steel. The other knife I saw it was on was a knife that was destroyed on a bench grinder by a hack in his basement. Also discolored and obvious.

Can we think about this before defaulting to pointing the finger at Spyderco and assuming they are burning edges despite not having any proof of this happening.

I'm backing off on assuming "burnt edges" from sharpening these days as well. At least from Spyderco. Eric recently mentioned on a podcast that they use a coolant when grinding and sharpening. That said, mistakes happen.

[Kenneth1977]

I've seen some nasty stuff embedded in low end paper that boxes are made of, and the starch that glues it all together is really hard and plenty capable of chipping an edge if it hits right. This does seem like something more due to a nasty wire edge fracturing off, I would not expect this from a clean apex unless you banged it against a hard surface or maybe caught a staple you didn't notice.

Well I have a few knives that I use for cutting up boxes and none of them have ever had this issue and there’s not been anyone else use my knife and also there hasn’t been any unknown damage.
I may reach out to spyderco and see what they say just to see.

[mongo1958]

I have had this knife for less than a year and I do not carry it every day and only open boxes or cut cardboard, I have just noticed that there is some bad chipping at the end of the blade. I really would have thought this would have stood up better. https://imgur.com/a/yrMz9hJ

FYI, some card board does have large staples in it.

[awa54]

I don't get this automatic default to "burnt edges" . We know the sharpening is done in a way that prevents it. I'd really like to see some proof that Spyderco has burnt edges. Sure I know in theory it can be possible with some sharpening jobs somewhere. I've seen it on one new knife in my 50 years of knife use and it was discolored and very apparent. It was an exceedingly thin knife made by a well known maker in Japan done with "R2" steel. The other knife I saw it was on was a knife that was destroyed on a bench grinder by a hack in his basement. Also discolored and obvious.

Can we think about this before defaulting to pointing the finger at Spyderco and assuming they are burning edges despite not having any proof of this happening.

"Burned" or not, initial factory edges on more than a few of my Spyderco knives, in multiple steels and models, have been more fragile before reprofiling (to a lower angle mind you) than after.

Who cares about blaming anyone? just accept that it happens and correct the problem by exposing metal that hasn't been directly affected by a high speed abrasive process then move on to enjoying your knife ...if that doesn't fix the issue send it back to the mother ship.

[Bolster]

"There are those who sharpen their knives frequently, and those who cut with dull knives."

Like the inquisitors in the Monty Python skit, you need to add an option: "There are THREE, THREE options. There are those who sharpen their knife frequently, there are those who cut with a dull knife, and there are those with so many knives they can always find a sharp one waiting to be used."

I'm backing off on assuming "burnt edges" from sharpening these days as well. At least from Spyderco. Eric recently mentioned on a podcast that they use a coolant when grinding and sharpening. That said, mistakes happen.

I'm interested in this topic, because I do some machining. As I understand it, flooding with coolant lowers the temperature, but it doesn't necessarily mean that there is no heat. When talking about grinding a thin piece of metal, like an edge, I've yet to read/hear that the coolant is so efficient that it guarantees the edge stays below the tempering temperature at the very edge.

I'm not arguing...I just don't know. But heat in cutting and grinding operations is not a binary thing, that either there's heat or there's no heat. With coolant, there's less heat.

[dull&blunt]

All I can add is I've not experienced anything like the OP with my PM2/Cruwear (KC DLC). It's only a few months old but I've cut up a lot of cardboard, plus a kitchen work and random tasks with it. I've purposely been testing/trying the factory edge and it remains sticky sharp. Nothing like the damage shown. The OP's tip is especially worrisome, looks like a good bit is missing.

[JSumm]

Doesn't Spyderco sharpen on some kind of wheel? This would lead to a bit of a concave edge grind versus a slight convex you may get from hand sharpening even though not intended. I find that my hand sharpened edges hold up better than the factory even with a more acute angle. YMMV

[HolySteel]

All I can add is I've not experienced anything like the OP with my PM2/Cruwear (KC DLC). It's only a few months old but I've cut up a lot of cardboard, plus a kitchen work and random tasks with it. I've purposely been testing/trying the factory edge and it remains sticky sharp. Nothing like the damage shown. The OP's tip is especially worrisome, looks like a good bit is missing.

Yes. The OP's photo makes me realize that I'm weird when it comes to examining knives - I would have noticed that tip within 15 seconds of opening the box. I also run my loup along the blade edge.

You guys are very gentle. I have more thoughts on this, but Paige Spiranac is sharing her golf knowledge right now and I can't seem to think straight.

[Bemo]

"There are those who sharpen their knives frequently, and those who cut with dull knives."

Like the inquisitors in the Monty Python skit, you need to add an option: "There are THREE, THREE options. There are those who sharpen their knife frequently, there are those who cut with a dull knife, and there are those with so many knives they can always find a sharp one waiting to be used."

I'm backing off on assuming "burnt edges" from sharpening these days as well. At least from Spyderco. Eric recently mentioned on a podcast that they use a coolant when grinding and sharpening. That said, mistakes happen.

I'm interested in this topic, because I do some machining. As I understand it, flooding with coolant lowers the temperature, but it doesn't necessarily mean that there is no heat. When talking about grinding a thin piece of metal, like an edge, I've yet to read/hear that the coolant is so efficient that it guarantees the edge stays below the tempering temperature at the very edge.

I'm not arguing...I just don't know. But heat in cutting and grinding operations is not a binary thing, that either there's heat or there's no heat. With coolant, there's less heat.

So you're saying there's THREE options.....

[Bolster]

So you're saying there's THREE options.....

Ha!

Our *three* options are heat, no heat, and less heat.... Amongst our options...are such elements as: heat, less heat.... I'll come in again.

[The Mastiff]

"Burned" or not, initial factory edges on more than a few of my Spyderco knives, in multiple steels and models, have been more fragile before reprofiling (to a lower angle mind you) than after.

Who cares about blaming anyone? just accept that it happens and correct the problem by exposing metal that hasn't been directly affected by a high speed abrasive process then move on to enjoying your knife ...if that doesn't fix the issue send it back to the mother ship.

If I saw it and ruled out the other variables than I'd probably believe it but I have yet to see it . Not where there were not other variables involved anyways. The last for me was a S30v Native from Wal Mart so before 2010 or so? No way I could rule out things like burrs or contaminants in the cardboard or tape.

[HolySteel]

"Burned" or not, initial factory edges on more than a few of my Spyderco knives, in multiple steels and models, have been more fragile before reprofiling (to a lower angle mind you) than after.

Who cares about blaming anyone? just accept that it happens and correct the problem by exposing metal that hasn't been directly affected by a high speed abrasive process then move on to enjoying your knife ...if that doesn't fix the issue send it back to the mother ship.

If I saw it and ruled out the other variables than I'd probably believe it but I have yet to see it . Not where there were not other variables involved anyways. The last for me was a S30v Native from Wal Mart so before 2010 or so? No way I could rule out things like burrs or contaminants in the cardboard or tape.

Trying to imagine burrs and contaminants in cardboard or tape that would take the tip off a new knife. But something did it - I can't imagine it left the factory that way.

I'd like to see a really good close-up of that tip.

[RustyIron]

I'm interested in this topic, because I do some machining. As I understand it, flooding with coolant lowers the temperature, but it doesn't necessarily mean that there is no heat.

You are correct. Alas, my knowledge is only enough to get by... barely.

When cutting metal, whether it's with a high-speed drill bit, carbide lathe tool, or particle of aluminum oxide glued to a belt, you're tearing chunks of metal off of your work. Take the point of your file and gouge a chunk of aluminum or steel. You're just digging a big divot out of the metal. That's what machining and grinding is. This produces heat... a LOT of heat.

A quick googling told me that the heat at the tool tip can be 1100 degrees Fahrenheit to 2200 degrees Fahrenheit. But that temperature is only at a very small area. The material being cut carries away the heat. As you know, if you're cutting too deep, too fast, you make more heat than the material can carry away, and things overheat.

Overheating is mitigated through he use of coolants. Coolants carry away heat more quickly. Stick your hot frying pan under the faucet to see how this works. Now take that frying pan and put some water in it. Put it on the stove. Pretty soon, the water will be boiling.

How hot is your frying pan? On the inner surface that's in contact with the water, the temperature is going to be close to 212 degrees. But the outside of the pan, the part that is in contact with the flame, is going to be over 1000 degrees. This is a great example of what happens to your knife blade. At the microscopic level where molecules are being torn from one another, it's really hot. Further back from the edge, the blade is room temperature.

How does this affect the usability of our knives? Beats the heck out of me. I'll leave it to the forum to figure out. All I really care about is that my knives are easy to sharpen and that they cut stuff up.

[standy99]

I am just going to throw this out there.

I’m on a watch forum and for 15 years every watch that has ever been dropped by somebody has been from 2ft…..always “my expensive watch is ruined and couldn’t even take a fall from 2ft. Funny as who’s arm or counter top or whatever is level with their knee…

I am definitely not saying the OP has indulged in a bit of…..
But it’s seems to be always cutting cardboard only on knife forums.

Have no reason to judge anyone but just making an observation.

[Brock O Lee]

Yeah, my best guess is damage caused by opening cardboard boxes, full of ceramic tiles. No staples involved.

[Bolster]

You are correct. Alas, my knowledge is only enough to get by... barely.

I surmise that you and I went to the same school.

When cutting metal, whether it's with a high-speed drill bit, carbide lathe tool, or particle of aluminum oxide glued to a belt, you're tearing chunks of metal off of your work. Take the point of your file and gouge a chunk of aluminum or steel. You're just digging a big divot out of the metal. That's what machining and grinding is. This produces heat... a LOT of heat.

A quick googling told me that the heat at the tool tip can be 1100 degrees Fahrenheit to 2200 degrees Fahrenheit. But that temperature is only at a very small area. The material being cut carries away the heat. As you know, if you're cutting too deep, too fast, you make more heat than the material can carry away, and things overheat.

Overheating is mitigated through he use of coolants. Coolants carry away heat more quickly. Stick your hot frying pan under the faucet to see how this works. Now take that frying pan and put some water in it. Put it on the stove. Pretty soon, the water will be boiling.

How hot is your frying pan? On the inner surface that's in contact with the water, the temperature is going to be close to 212 degrees. But the outside of the pan, the part that is in contact with the flame, is going to be over 1000 degrees. This is a great example of what happens to your knife blade. At the microscopic level where molecules are being torn from one another, it's really hot. Further back from the edge, the blade is room temperature.

How does this affect the usability of our knives? Beats the heck out of me. I'll leave it to the forum to figure out. All I really care about is that my knives are easy to sharpen and that they cut stuff up.

Very edifying and satisfying post. Thank you sir. This broaches the possibility that even coolant-assisted grinding leaves the potential for a small amount of metal to be heated beyond the temper. Judging by reports, it must be a very small amount, since a manual sharpening or three seems to make for more edge stability, for most folks.

One more comment for those who are not machine-heads. Where you say "if you're cutting too deep, too fast, you make more heat than the material can carry away, and things overheat," that's very true. It is also true that if you are not cutting deep or fast enough, if your cutting tool is essentially skating on the surface, you are ALSO in grave danger of overheating. If a drill bit, for example, is spinning in the hole and not cutting, then it is generating a lot more heat, than if it were cutting. If your sandpaper belt is too worn, it will heat rather than cut. That's why getting the right "feeds and speeds" is so important. My machinist teacher always recommended "plenty of, but not too much" down pressure when drilling. If he'd see a bit spinning and not cutting, he'd start yelling!

[kennbr34]

It's been a while since I spent any time in a machine shop, but I seem to remember that cutting bits were a lot larger at their edge apexes than a knife's edge apex would be. If not just due to them being typically much more geometrically obtuse, but also just because having a metal cutting bit with an edge as keen as a knife blade's wouldn't really aid cutting metal.

I would still give the benefit of the doubt to Spyderco to have actually tested and ensured that the coolant was doing its job, but it could also just be at the functional limit of the coolant to actually conduct heat away from the metal quickly enough at that microscopic level; especially since the the less metal there is in any given area, the faster it will heat up. In other words, Spyderco could have (and probably did) design and test the coolant system to ensure that it prevented the grinding wheels from ruining the temper of the blade overall, rather than focusing on whether the very edge was being burned. After all, it it's probably not worth spending that much extra attention just to make sure the factory edge isn't burned, considering how quickly most users will resharpen anyway.

Anyway, that's just my humble opinion on whether the coolant makes the burnt edge theory impossible, not that it's most likely what happened here.

Three theories have been proposed...

1. This one is a lemon and the heat treat was bad.
2. The edge is burnt somehow
3. The knife hit something hard without the OP realizing it

At the risk of seeming like I am reaching to make a pun, but it's kind of an Occam's Razor thing. Number three is the simplest answer, so I'm gonna guess that's what happened. Plus, something else I don't think anyone has pointed out yet: Even if the steel was as brittle as glass, cardboard wouldn't do that.

And I don't think it implies any carelessness by the OP. The thing about cardboard is that it can have nasty surprises in it, especially depending on where it came from, what it was used for, how it was manufactured, etc. I once had a box from an irrigation supply company that had a bunch of survey flags in it--you know, the little metal ones you stick in the dirt to mark where pipes will lay. Well, someone had stuck one of those into one of the corrugations of the cardboard, so when I sliced it, the edge hit it and got rolled pretty bad. I have also heard of people finding wires impregnated in the material as if someone piece of screen had fell into the pulp during manufacturing. You gotta consider too how much cardboard is recycled, so there could be all kinds of debris in it that doesn't get filtered out of the mix.


As a side anecdote... This reminds me one knife I used to carry that had an open back, and my keys or coins would always manage to slip in there and ding the edge up. Took me a while to realize that it was happening, and I was convinced it just had a bad heat treat. Then one day, I went to open it and noticed a quarter wedged between the liner and the blade and it all clicked.

[dlum1]

Agreed. I think coolant can only pull heat away so quickly. And we're talking just a few micrometers at the very edge. All things considered, I'm rather impressed. Imagine how damaged the edge would be if coolant wasn't used.

[Kenneth1977]

It’s funny that a lot are saying that basically I’m lying about “ only cutting cardboard “ but that’s the truth , I may have cut some meat at one point but that was in the first few months of having it.
I’m aware of some boxes having staples but I can assure anyone that the boxes I have cut didn’t have any. I have had one other knife that had a little small chip on the edge and that was a Bradford guardian three in 3v and I lightly sharpened it on a diamond stone and came right and never had any issues after that.I take care of my knives and don’t drop them on concrete or try and destroy them , I have a few busse knives that could take all kinds of abuse but I don’t do that to them.

[weeping minora]

A side note, whilst still remotely on topic here, I find it confoozling how so many folks can have their knives last weeks or months with just stropping a factory edge . Seriously boys and girls, you pay so much for these tools, it's more than worth the investment to learn how to properly maintain them.

Back on topic, to the OP and to anyone else, please, do yourselves a favor upon receiving your new Spyderco knife and sharpen it before you put it to use. I'd be astonished if anyone has nearly the amount of issues that are experienced from those who want to "ride the factory edge", after doing so. Seriously, it's like buying a brand new sportscar and you won't even start the engine. Don't let your knife be a garage trophy/weekend warrior. Be like Nike boys, Just Do It.