Burnt factory Edges

[NortonT]

I would like to know what Sal and or Eric think about the factory edge.
Specifically all the comments folks have about burnt factory edges. I'm
very happy with the factory edges for all my spyderco knives. I have 50
spyderco knives in various models and most steels. Recently I got a Sage 5
in rex121. I love K390 and 15v. Most of my collection are running the
factory edge and stropping them with diamond emoltion spray on a leather
strop brings the edges back to hair popping. I do have a wicked edge fixed
sharpening system. I have a shaman in S30v at 12 degrees at mirror polished
and love that edge. The factory edges especially on the super steels seems
good enough to me. How much truth is there to burnt edges? I would think
that when the factory sharpens the knifves they would take care not to over
heat the edge. I am very curious about Sal and or Eric's input on factory
edges. Thank you to every one and God bless ! Spydie junkie... -----Terry

[TazKristi]

Hi, Terry:
Welcome to the Spyderco forum. We hope you enjoy your time with us.

Kristi

[Vamais]

People do sometimes report better edges after a few sharpenings.

Could it be due to the method of sharpening, and have nothing to do with the edge being overheated/burnt?

I do wonder if the steel right on the surface of the heat treated blade has different properties than the steel farther in. Heat diffusion does take time (albeit not much in a conductive metal over small distances), so I wonder if that may be what causes the difference between factory edges and edges after a few sharpenings.


Just two theories, with no supporting data.

[jwbnyc]

I have one PM2 that has discoloration at the tip. I assume that’s what it is. I just keep an eye on it.

[knivesandbooks]

I think edges are generally burnt from factory no matter the maker. Unless they’re hand sharpened, I don’t know how they wouldn’t be. Might be wrong though! Always felt like I got better edge performance after a couple sharpenings. In fact, I think a lot people saying S30v is chippy are probably still on a factory edge. I have had multiple S30v knives chip on the factory edge but not chip again after sharpening. As for me, whether I sharpen it immediately or use the factory edge just depends on the knife. I don’t really feel like the factory edge finishing is anything on the representation on the product so long as the bevels are even. My last Spyderco purchase was a k390 leaf jumper and it had a burr across the entire edge, so I sharpened it. I’ve received Spyderco that were extremely sharp with well finished edges and some that needed a little work. For serrated knives, I’ve learned from this forum to put them to the Sharpmaker when I first get them to round the teeth a bit.

[TkoK83Spy]

I have one PM2 that has discoloration at the tip. I assume that’s what it is. I just keep an eye on it.

I've had similar on my 52100 Manix and AEB-L Urban...very similar steels, but always found that curiously odd.

[yablanowitz]

The robot that does the sharpening at Golden does so under coolant. It's still possible to overheat the edge, but it is far less likely to happen. All in all, there are too many variables in play to generalize about factory edges.

[JoviAl]

On some knives I’ve found the first couple of sharpenings a bit ‘glassy’ on the abrasives, but nothing to get upset about. Whether or not that constitutes a ‘burned’ edge is moot to me personally, as it is a temporary condition that is gone within a few days on my work stuff or a few weeks on my home stuff I apologise if this makes me sound dismissive - I don’t mean to be, I just find it to pass very swiftly and become academic.

I sometimes wonder if a ‘burned’ edge is actually somewhat of an advantage on some steels I’ve found- SE H1 for example has been mentioned in the past to have superb edge retention from factory. In my experience of using it all day at work I find out of the box it is stellar, then it seems to drop off slightly in longevity (still pretty excellent though) but gets to a higher initially sharpness (or aggression depending on protocol). The only knife I’ve ever received from Spyderco that is so glassy I just cannot get on with is my M398 Mule - no matter what I do I just cannot get a decent edge on that thing, to the point where it has been relegated to the Cupboard of Shame. I’ve tried everything from mechanical grinding to diamond plates to ceramics Somewhat of a curious anomaly

[Brock O Lee]

Outpost 76 has so many tests that show improved edge retention on edges after the factory edge. This includes many Spydercos. I am not sure why this is the case, given that sharpening is water cooled. My subjective experience lines up with his results.

He typically gets twice the edge retention on edge #3 to #4 compared to the factory edge. This varies by manufacturer, steel, and heat treatment, but I think it can be taken as a general rule of thumb. After edge #4 performance remains stable.

Hint: listen at 1.5x speed...

[JFR1]

My CRK was just like my Spydercos… first couple of sharpenings the edge was brittle. Once I got into the good steel after a couple sharpenings it’s fine. It’s not just Spyderco. I also assume it’s unavoidable unless the edge is done without powered equipment.

[sal]

Hi Terry,

Welcome to our forum and thanx much for your interest and support across the years.

I know that there are many people that test knives for a variety of performance indicators. I love the fact that they do that and I applaud their efforts. I watch a lot of these tests, as time permits, and I learn from all of them. Some I think are better than others, but all have their value.

I think of the edge as something that comes and goes with use. I have never personally experienced burned edges. Those that claim to have tested and found burned edges from factories and improved performance after one or several sharpenings is not something that I can confirm or deny. We use a CATRA for testing edge retention and have been doing so for more than 20 years. We update our testing equipment and machines regularly so we believe our results are accurate. We try very hard to give our customers the best edge possible, from a factory, that we can, but we recognize personal preferences as well.

Some folks never sharpen their knives, some are obsessed with it. I think that's great when people get so OCD about something to delve down deeply into their results. I do the same with many aspects of knives. This is great information for all of us that enjoy the use of knives. We all get to learn.

I still feel that "the edge is a ghost" that we will continue to study and learn about for many years to come. I'm pleased that we can offer pieces with exotic materials that many find to be exceptional in their performance. That's our "purpose" in our industry.

I knew one knife "afi" that would re-sharpen his brand new knife before using it to the edge of his choice. I never felt that his edges were as sharp as the factory edges, but I would never say that what he was doing was good or bad. It was his way, which I believe we are all entitled to have.

I'm always sharpening knives. I have sharpeners all over my desk and counters. I look at different edge angles with different blade materials. I have a Goniometer and se-ups for 20 degrees, 30 degrees and 40 degrees. I'm usually using and testing as many as 20 models at any given time, so it's a constant effort. I also use a variety of magnification to visually see results..

In the end, getting information from all sources is good, but your own experience is not to be under estimated.

Hope that helps.

sal

[RazorSharp86]

I always prefer my own edges on knives.
When you sharpen, you have much better control over the variables (edge finish, edge angle, etc).
I also find that edges that come from factory, because the knives are sharpened on belts, tend to have very uneven bevels (likely due to belt “chatter”).
I always find that edge retention improves after a couple of sharpening sessions, whether it’s because factory edges are burnt or simply aren’t as fussed about as the ones I put on my knives.

However, important to note that Spyderco edges are some of, if not the absolute best factory edges out there.
Especially as of late.

[zhyla]

How much truth is there to burnt edges?

I’ve never seen a photo of a burnt edge. I don’t remember seeing a thread about it. What are we talking about here?

As someone who has burnt my share of blades, I can tell you that the damage to the heat treatment becomes invisible with the next pass on the grinder, even though the damage is done.

I think edges are generally burnt from factory no matter the maker. Unless they’re hand sharpened, I don’t know how they wouldn’t be.

This is absolutely not true. Wet grinding is an easy and safe way to grind heat treated blades. I’ve never bought a blade from any manufacturer that showed any lack of hardness on a factory edge.

When you blow the temper on the thin part of a blade it’s usually all the way thru. No amount of re-sharpening will bring that back.

[knivesandbooks]

How much truth is there to burnt edges?

I’ve never seen a photo of a burnt edge. I don’t remember seeing a thread about it. What are we talking about here?

As someone who has burnt my share of blades, I can tell you that the damage to the heat treatment becomes invisible with the next pass on the grinder, even though the damage is done.

I think edges are generally burnt from factory no matter the maker. Unless they’re hand sharpened, I don’t know how they wouldn’t be.

This is absolutely not true. Wet grinding is an easy and safe way to grind heat treated blades. I’ve never bought a blade from any manufacturer that showed any lack of hardness on a factory edge.

When you blow the temper on the thin part of a blade it’s usually all the way thru. No amount of re-sharpening will bring that back.

I hope this doesn’t come off as argumentative because I don’t mean it that way and I’m not arguing. If the edge isn’t burnt, why does it seem that after a couple sharpenings or more you get longer lasting edges? Is it not the case you’re getting to better steel? I always thought that was true.

[zhyla]

I hope this doesn’t come off as argumentative because I don’t mean it that way and I’m not arguing.

Not argumentative at all. By the way, here’s a discussion of this topic with a conclusive statement:

viewtopic.php?p=1610838#p1610838

Well, conclusive if you believe this “Sal” guy.

If the edge isn’t burnt, why does it seem that after a couple sharpenings or more you get longer lasting edges? Is it not the case you’re getting to better steel? I always thought that was true.

Almost nobody does anything remotely scientific when forming an opinion about something as invisible and difficult to measure as steel heat treatment. I would question the very premise of this thread solely on the lack of data. If someone had, say, a CATRA test where they took 100 new Spyderco knives and got CATRA numbers on them and then sharpened and compared, that would be a useful starting point.

It’s really easy to convex edges when you’re sharpening. Convex edges may resist rolling better. That would be my off the cuff explanation.

Think about how little material you remove when you sharpen. Do you really think just the first 0.001” of steel is “burnt”?

[Mage7]

How much truth is there to burnt edges?

I’ve never seen a photo of a burnt edge. I don’t remember seeing a thread about it. What are we talking about here?

As someone who has burnt my share of blades, I can tell you that the damage to the heat treatment becomes invisible with the next pass on the grinder, even though the damage is done.

I think edges are generally burnt from factory no matter the maker. Unless they’re hand sharpened, I don’t know how they wouldn’t be.

This is absolutely not true. Wet grinding is an easy and safe way to grind heat treated blades. I’ve never bought a blade from any manufacturer that showed any lack of hardness on a factory edge.

When you blow the temper on the thin part of a blade it’s usually all the way thru. No amount of re-sharpening will bring that back.

Check out this series of videos related to this subject:



I can also tell you that as a machinist, I have seen plenty of burnt tool bits, and it's much more apparent when this is an issue with a metal cutting bit because an improper temper will be much, much more observable on lathe spinning a few hundred RPMs than someone cutting a few lbs of cardboard or rope.

I agree that most things that people attribute to "burnt edges" are probably misattributed, if even quantifiably observed at all. I think most people tend to blame any problem they have with a factory edge on it being "burnt" regardless of whether that makes sense or not. Half the time, were talking about situations where over-heating will not even have a uniform effect from one steel to another. For example, one steel that gets overheated may become too brittle to retain edge stability, whereas another may become annealed and actually end up softer.

But it's definitely a real thing.

[Guts]

Outpost 76 has so many tests that show improved edge retention on edges after the factory edge....

Hint: listen at 1.5x speed...

Okay, so I'm not the only one who's done that with his videos


Back on topic, I've experienced what I think is a burnt edge on a Maxamet knife, which I also think is weird since as mentioned the edges are sharpened with liquid cooling. However, my Maxamet PM2 edge would just crumble. This wasn't the first/only Maxamet knife I owned and sharpened up to that point. The other Maxamet knives I sharpened prior to the PM2 all took great edges no problem (Native 5, Manix, and Para 3). Sharpened everything the same, freehanded on resin bonded diamond stones, so idk what was up with my Maxamet PM2 in particular. Took me like 5-6 edges before I felt like I got to "good" steel. It's a beater knife so whatever. I've had brittle edges with other brands/knives as well, but that PM2 was the worst one I've personally experienced.

[JoviAl]

Outpost 76 has so many tests that show improved edge retention on edges after the factory edge....

Hint: listen at 1.5x speed...

Okay, so I'm not the only one who's done that with his videos


Back on topic, I've experienced what I think is a burnt edge on a Maxamet knife, which I also think is weird since as mentioned the edges are sharpened with liquid cooling. However, my Maxamet PM2 edge would just crumble. This wasn't the first/only Maxamet knife I owned and sharpened up to that point. The other Maxamet knives I sharpened prior to the PM2 all took great edges no problem (Native 5, Manix, and Para 3). Sharpened everything the same, freehanded on resin bonded diamond stones, so idk what was up with my Maxamet PM2 in particular. Took me like 5-6 edges before I felt like I got to "good" steel. It's a beater knife so whatever. I've had brittle edges with other brands/knives as well, but that PM2 was the worst one I've personally experienced.

That’s exactly what my M398 mule edge did - crumble. It just kept grinding off into a sort of very fine powder with no apex being left behind, no matter what variety of sharpening I tried. I lost interest in the end and shelved it, but I wonder had I kept on going if I’d have gotten through it Then again, I’d already taken a fair bit of steel off.

[jwbnyc]

Gerald over at Outpost 76 on YouTube has documented pretty large jumps in edge retention after sharpening new knives, usually 3X’s, going on quite a few years now. Worth a look. Whether that’s burnt edges or something else… I do not know. I think Gerald is on the forum sometimes. Maybe he’ll pop in and give his take.

Props to Brock O Lee..

[jwbnyc]

I have one PM2 that has discoloration at the tip. I assume that’s what it is. I just keep an eye on it.

I've had similar on my 52100 Manix and AEB-L Urban...very similar steels, but always found that curiously odd.

Mine is s30v.. it’s just the faintest brown. It’s been sharpened out on the edge but remains on the spine side.

I’ve read about this at the tip on knives before. Don’t have any others like that, though. I just try to stay aware of it when using that knife and try not to drop it, just in case.

Decided to add a pic:



You can just make it out. It seems to be sharpening out as I use the knife. There it is, anyway.

Apologies for the crap picture. I am not a shutterbug.