Steel That Just Won't Take an Edge?

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jemelby

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I recently finished up a training excercise in south LA. (not the City of Angles). I took my recently aquired Edgepro Apex shapening system, and set about sharpening every knife I could get my hands on. I sharpened 20-30 Benchmades. Several dozen Cuda, Kerhsaw, Buck and Spydercos. All told, I probobly sharpened 200 knives.

Some knives just won't sharpen. Period. Mostly, I've found that the cheap 425 Gerbers won't take an edge despite hours of work. Not even the 3-4 Applegate-Fairbain folders I tried to sharpened would take an edge. This is not an issue of wear resistance. I took a solid 1/32 of an inch of the edge of one Gerber, and still couldn't get it sharp.

440A, while a budget steel, sharpens very well. Shaving sharp every time. Of course, with 440A, sharp every time means sharpening every day :-)

My question is: What steel has the least "sharpenable" characteristics? I understand the basic concepts of steel make-up, and have read the good FAQs. I'm just a bit curious about which "recipe" sucks for taking an edge? I believe that the vadnium content of S30V makes it the winner for taking an edge, but which one REALLY sucks?
 
I dunno what the story is, but I've ran into this too. Some knives just sharpen up in no time, and others will never take an edge. I'm no expert, I just guess that it may have more to do with the heat treat than the steel.
 
I don't understand any of this.


I've never found a knife I couldn't put a razor edge on. I've been sharpening for close to 50 years.

Whether it would hold the edge very long under use was another issue.


Thomas Zinn
 
zinn1348 said:
...I've never found a knife I couldn't put a razor edge on...
Click to expand...

I've only been at it 35 years, so I still have a trick or two to learn. I would dare to say I mastered the art of hand sharpening, and hand honing befor I got an edgepro. Most of my experience comes from sharpening wood working tools. Planes, chisles, saw blades, and such as that. I've never run into a tool steel I could not sharpen to a "scary sharp" edge.

But the fact remains. I HAVE encountered knife blades that I could not get razor sharp. I am reasonable certain that I have ruled out technique. That leaves the steel, to include, perhaps, the heat treat.

So the question stands, despite zinn1348's boast... What steel sucks for sharpening?

I would like to clarify, I am not asking which steel is most difficult to sharpen. S60V and BG-42 can be "difficult" to sharpen because of their wear resistance. but they eventually will take a very nice edge.
 
How much sharpening experience do you have? You said you just recently aquired an Edge Pro Apex so I wouldn't expect anyone to be 100% proficient with it right away, it takes practice. To be able to consitently put a razor edge on a knife it takes skill and knowledge. When I first got my Edgepro I got some knives very sharp, others I had problems with. This was due to my lack of experience and understanding of sharpening.

Now that I know a great deal more about sharpening I have never ran into a knife I couldn't put a razor, hair shaving, edge on.

My first guess would be on some of the knives you weren't getting all the way to the edge, even if you think you were. Or you did get to the edge with a corse stone and then you switched to a finer stone that maybe hitting a a slightly different angle which is polishing the bevel and not the actual edge itself. I believe this can be an issue with the Edge Pro as some of the stones may vary in thickness. Also if you have sharpened that many knives without flattening your stones this is probably a more reasonable cause. Put a metal straight edge across your corser stones and see if they are dished in the middle. If you use a badly dished corse stone and swithc to a non-dished fine stone you're going to have BIG problems.

Before I was careful about making sure my Edgepro stones were flat I had problems from this.

Why some knives and not others? All depends on what you had to do to them. Maybe some of them required more honing with the potentially dished our corse stone, resulting in the edge being more off angle, and then when you switched to the finer stones they weren't hitting the edge. Maybe some you started with a finer stone as they needed less work?
 
You can thank crappy heat treats. My Gerber LST wouldnt take anything that resembled an edge
 
BTW, if you can get ahold of one of these knives you couldn't get sharp, I'd be willing to check it out if you wanted to send it to me. If I can't sharpen it we could send it off to one of the super expert sharpeners like Jeff Clark. :)
 
GarageBoy said:
You can thank crappy heat treats. My Gerber LST wouldnt take anything that resembled an edge
Click to expand...

I've put nice sharp edges on my Gerbers, like EZ Out's, Gator, etc. I want to try and sharpen one of these so called unsharpenable knives. :) I CAN SHARPEN BUTTER DAMN IT! :P
 
jemelby said:
I've only been at it 35 years, so I still have a trick or two to learn. I would dare to say I mastered the art of hand sharpening, and hand honing befor I got an edgepro. Most of my experience comes from sharpening wood working tools. Planes, chisles, saw blades, and such as that. I've never run into a tool steel I could not sharpen to a "scary sharp" edge.

But the fact remains. I HAVE encountered knife blades that I could not get razor sharp. I am reasonable certain that I have ruled out technique. That leaves the steel, to include, perhaps, the heat treat.

So the question stands, despite zinn1348's boast... What steel sucks for sharpening?

I would like to clarify, I am not asking which steel is most difficult to sharpen. S60V and BG-42 can be "difficult" to sharpen because of their wear resistance. but they eventually will take a very nice edge.
Click to expand...


Sorry to disagree, it's no boast, it's fact.


Thomas Zinn
 
WadeF said:
I've put nice sharp edges on my Gerbers, like EZ Out's, Gator, etc. I want to try and sharpen one of these so called unsharpenable knives. :) I CAN SHARPEN BUTTER DAMN IT! :P
Click to expand...


Agreed. I used to sharpen tin can lids, just for fun.


Thomas Zinn
 
I've found that some steels, especially the difficult low carbon stainlesses require a bit of care to get razor sharp. Most of my troubles with sharpening cheap stainless seem to stem from using hones with dull grit on the topside. An important thing is to use a very sharp grit, doesn't matter if it's coarse or fine, just as long as surface is fresh and sharp, otherwise (especially on coarse stones, but it happens on finer ones sometimes too) the rounded abrasive particles tend to blunt or flop the edge around instead of cutting into it. This may not be the problem you're having, but it sure has helped me.
 
I defnitely noticed that certain steels sharpen easier than others. Its not so much that a certain steel is not getting shaving sharp, so far I haven't encountered one that wouldn't, but some steels require a lot of care and attention during sharpening, while others seem to be almost eager to get sharp. I think the "gummier" the steel is the more difficult it is to get them sharp. I hate 420HC; ATS-34, VG-10, S30V sharpen for me without problems, no special care required. Even though S30V is a b**** to reprofile I don't find it any more difficult to sharpen than the other. But the HC steels like Shirogami, Aogami and A2 I can sharpen blind and while half asleep. I think the main problem is the burr (even if it can not be felt) just bends out of the way instead of getting cut of properly which give the feeling of a "rubbery" steel....if that makes any sense?
 
Yea, I've got some stainless kitchen knives that the steel is gummy and like rubber. Pretty much the only way I've found of getting an edge on them is to profile them, and then, using a higher angle, make a longitudinal stroke (as if trying to slice a loaf of bread) on both sides to rip off the "rubber edge" before moving to the next stone.
 
Any steel will take an edge. It may not take it for very long but it will take it initially. I suspect Jemelby's problem relates to pressure. If his experience is with harder steels, he may be applying too much pressure for a soft (gummy) steel. The result is that the edge deforms as it is being ground. It never gets a chance to get straight and sharp.

Jemelby, if you are good at feeling for the burr as you grind, then go at the soft blades again but with lighter pressure. Feel the burr after each pass with the sharpener and compare it to what you feel with the harder steels. Once you get the pressure light enough that it (the burr) behaves like the harder steel does with higher pressure, you will get an edge. After that you can make the bevel angle more obtuse so the edge will last longer. Take care.
 
If you go really low end, the $5 swords and such, you can get steels with horrible grain and if you break them it looks like nodular iron. It can be hard to get them to a fine edge as they just don't polish well. I just file knives like that, you can shape them decently, but going above a coarse edge finish isn't very productive.

If you are taking 1/32" of an inch off the edge, then you are obviously removing enough material. I would assume there is a huge burr forming that is just being pushed around. After you set the initial edge make sure this is cut off by adjusting the angle a couple of degrees higher and making a couple of passes.

-Cliff
 
Soft high alloy steels are the hardest for me to sharpen, they shape up fine but they form very ductile burrs, they just flop, and when they do break off they leave a jagged edge.

I use a belt sander on these and they sharpen up without incident usually.


Harder steels the burr is harder, stays in place and can be cut off with a ceramic stick (corner of a 204 rod) or abbraded away with light strokes on a hone.
 
It took a little bit of hemming and hawing, but the thread is finally getting around to the heart of the matter :-) What steel is most problematic to get the scary sharp edge?

So far, "soft, high alloy steel", "rubbery steel", and steel with a "ductile burr" have been sited as trouble spots.

I have also seen some reference to steels that sharpen great. And eventhough I have done 200+ knives with an edgepro, I've not been using it all that long, and I've picked up some great tips on how to deal with some of the problem steels.

What is still lacking, is by-name reference to what steels you all find annoying to sharpen. I'll start out with an example:

"I find 425 steel to be a bastard to get a super fine edge on." "I can easily grind steel off the edge, and have no trouble 'working the burr.' but in the end, the edge is always unexciting, and plain (not scary) sharp."
 
I have found Opinels (whatever high carbon steel they use) to be very hard to put an edge on. I have one that has large chunks of the edge come off when you put it on a coarse stone. I don't know if it's heat treat or steel, but it was a complete waste of money to buy these knives.

I have found S30V to be difficult to put a really sharp edge on also.

Some of the easiest for me have been 1095, VG10, and D2. All ground very thin first. They just have a "feel" for them....
 
Opinels have a very acute edge and a coarse hone will gauge visible hunks out of it, I adjusted the edge on one after a friend put a working obtuse bevel on it, and using coarse sandpaper (80 or 100 grit) there were ~mm pieces missing. You have to work the edges of these with fine hones.

-Cliff
 
I have found Opinels (whatever high carbon steel they use) to be very hard to put an edge on.
Click to expand...

My experience has been the exact opposite. I can put an edge on an Opinel that is exceptionally keen with little trouble. Such a knife will readily outcut knives costing 30X as much. I keep some with a course sliciing edge and some with a finer wood working edge.

I have used 100grit Ao belts to reprofile the blade and leave a very course edge on, and it will slice through 1" rope like butter due to thevery thin and aggressive edge, downside is that it is more prone to tear outs and thus edge retention suffers, but a few strokes on a course belt without the grinder running, or w/ file solves that in seconds. While this will wear down a blade quicker, they are cheap enough to replace that it is not an issue.

I have a Model 12 (a big one) that I sharpen with a file and use it as a folding bread knife, very effective.
 
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