Sharp
July 10, 2017 7:48 PM   Subscribe

 
Chad Ward provides what I believe to be the definitive guide on this subject.
posted by cubby at 8:01 PM on July 10, 2017 [16 favorites]


Metafilter: it's windbaggy, so be forewarned.
posted by wenestvedt at 8:31 PM on July 10, 2017 [4 favorites]


I've been using that Chad Ward guide that cubby linked to for years to sharpen my kitchen knives, and it didn't take me long before I was getting great results with laughably easy effort.
posted by Greg_Ace at 8:52 PM on July 10, 2017 [2 favorites]


Thanks for introducing me to Markerbuoy
posted by not_the_water at 9:20 PM on July 10, 2017 [2 favorites]


I took a peek at that Chad Ward site and quickly got judged so hard I fled whimpering into the night.
posted by darksasami at 10:29 PM on July 10, 2017 [4 favorites]


I've been sharpening with a firm cloth buff on a bench grinder for years. It works great, and does it pretty quickly, too.

The Chad Ward site offers generally decent advice. But I would take issue with this:
In general, the harder the steel, the keener the edge it will take. However, a hard steel makes it more difficult to get that edge in the first place. So manufacturers leave the steel a little soft, theoretically making sharpening at home easier. If you’ve ever spent an hour or two trying to get a super fine edge on a cheap kitchen knife, you’ll know that there is a big gap between theory and practice.
I've found harder steel does not take a keener edge. Like, at all. Harder steel will hold an edge longer. But softer steel, down to even high 40s Rockwell C, can take as sharp an edge as anything. Scary sharp, even.

Hard steel isn't necessarily more difficult to sharpen. It can be more difficult to grind. And some fancier harder steels can have relatively large carbides, which demands more attention to abrasives and techniques to get best results. For example, a cheap, softer blade will often get reasonable results with a simple pull through style knife sharpener and a steel. But those things can be ineffective at best with a fancy very hard blade.

And many manufacturers like to leave knives on the softer end of the spectrum because it makes them more durable. A fancy knife at 64 RC is much more likely to chip than one at 54 RC. Which will demand extensive grinding to fix, a more serious task than normal sharpening.

I've also come to think that raising a burr, part of the usual recipe for sharpening, is unnecessary, and possibly counterproductive for someone serious about sharpening, considering the ways sometimes described for removing that burr. Sharpening is a bit like cooking. You can follow a recipe and get good results. But once you understand and gain insight behind how and why the recipe works, you can figure out alternative ways to accomplish the task.
posted by 2N2222 at 11:32 PM on July 10, 2017 [3 favorites]


I just sharpen my knives on the concrete behind KFC like a civilized human being.
posted by Literaryhero at 2:32 AM on July 11, 2017


2N2222: I've also come to think that raising a burr, part of the usual recipe for sharpening, is unnecessary, and possibly counterproductive for someone serious about sharpening, considering the ways sometimes described for removing that burr.

I would love to see some scientific testing of procedures that raise and then remove a burr. Does it make the edge sharper or more durable somehow? Is it the quickest way to confirm that an edge is getting thin enough, even if it doesn't make the edge sharper? Or is it just mindless recipe-following?
posted by clawsoon at 4:23 AM on July 11, 2017 [1 favorite]


OooooH! A sharpening thread! When you learn how to sharpen, you can stop buying disposable tools or machines that rely on replaceable edges.

I use diamond stones like the ones Paul Sellers uses here, which is sort of a shorter demo of the first link. If I were starting out again I'd probably go for the plastic backed EZE lap diamond stones that work just as well and are are lighter.

I don't sharpen knives that often but need to do my chisels and planes repeatedly as I work and for those, unless I'm just touching up an edge, I always make sure I feel a tiny burr across the full width because it's the only way of ensuring that I'm starting with two intersecting planes, then about 30 strokes of the two finer grits and stropping and I'm done. The burr doesn't ever survive the stropping. There's no guesswork or wasted effort.
posted by bonobothegreat at 4:24 AM on July 11, 2017 [5 favorites]


bonobothegreat: I use diamond stones like the ones Paul Sellers uses here, which is sort of a shorter demo of the first link.

If you haven't seen it already, you might enjoy the counterintuitive result in this series of electron microscope images, in which the 325 grit diamond plate produces a better edge than the 600 or 1200 plates. The mystery is solved here.
posted by clawsoon at 4:31 AM on July 11, 2017 [5 favorites]


It's a derail, but this guy's accent makes me appreciate Bob Odenkirk's work performing Ernie in the Mr. Show Thrilling Miracles sketch.
posted by picea at 5:16 AM on July 11, 2017


A bit scared to go down this rabbit hole. I have the Trizor recommended by Sweethome. Is this something knife sharpening geeks would judge me for? Like, is a Trizor the equivalent of a Keurig machine whose owner will be crucified by coffee geeks? Tell me, but be gentle, please...
posted by The Toad at 5:20 AM on July 11, 2017


The Toad: Is this something knife sharpening geeks would judge me for?

Sharpening geeks are constantly judging each other for being Obviously Wrong About Everything, so of course you'll find someone to judge you, too, no matter how you do it. You might say... the knives are out.
posted by clawsoon at 5:24 AM on July 11, 2017 [4 favorites]


I would love to see some scientific testing of procedures that raise and then remove a burr. Does it make the edge sharper or more durable somehow? Is it the quickest way to confirm that an edge is getting thin enough, even if it doesn't make the edge sharper? Or is it just mindless recipe-following?

I, too, would like to see some scientific testing. Some burr removal methods seem to involve either pushing the burr back to a position where it is less detectable, or simply breaking off the burr. Either way, less than optimal results are achieved. Even with a good burr removal procedure, I have found that the steel remaining is also sometimes fatigued enough that it will roll fairly easily, even if that edge is perfectly razor sharp and good at demonstrating a hair shaving or newsprint slicing test. Depending on the context, this may or may not be a problem.

The reason burr raising is commonly used is as bonobothegreat says. It is an easy way to ensure the two planes have been ground to an intersecting line. When you think about it, once the burr is raised and is noticed, you've gone beyond the point where the two planes intersect. After a while, you can get a sense when that point is reached, and commence with stropping or micro beveling to a finish. This can help with reducing the chances of resulting in a sharp, but weaker than optimal fatigued edge.

A bit scared to go down this rabbit hole. I have the Trizor recommended by Sweethome. Is this something knife sharpening geeks would judge me for? Like, is a Trizor the equivalent of a Keurig machine whose owner will be crucified by coffee geeks? Tell me, but be gentle, please...

If it works, it works. I have no problem even when people use inexpensive tungsten carbide pull-through sharpeners, though they seem to garner a great deal of hatred among knife nuts. The reason I think they are useful is because for many people, they simply work. Take a dull knife, pull it through a few times, and it's sharper. What's not to like? I

For quick sharpening, nothing beats the power tool. Cloth buff for "power strop"/honing, belt sander to fix a damaged edge. Though care must be taken to not overheat the edge and blow out the heat treatment. And safety of course. But for regular sharpening. I often use a ceramic rod that I found. I'm not sure what it was intended for, but it seems to cut fast. Being ceramic, it's very hard, and even a light touch with its single point of contact can reveal a weak edge by making a burr that you might never have otherwise noticed. Which is nice since this rod is good enough to also grind that burr off to leave good steel behind. When more grinding is needed, I like diamond plates. I've found even cheap ones from Harbor Freight to be pretty sufficient. I have noticed like in that blog post that diamond plates can be somewhat irregular when new, and seem to level off after a couple uses. A few rogue high grits that tend to get pulled off/broken to leave a more uniform surface. When I used diamonds, it's to grind off a little more material, perhaps fix some small chipping. I have changed from water as a lube to glycerine. The reason is that it offers the same cooling effect and keeps the diamonds from loading easily, like water ( or oil, I suppose) would. But it doesn't just run off and dry like water does, needing constant replenishment. And it washes off easily under the tap, unlike oil, leaving a nice, clean, unloaded diamond plate ready for use again.
posted by 2N2222 at 5:43 AM on July 11, 2017 [2 favorites]


This post is just in time. I have a couple of opinel's that I've sharpened myself, but I still find the process really intimidating and want to (need to) sharpen my Shun knives. They are expensive wedding gifts and really important to me, so when I lived down in Brooklyn I'd get them sharpened at Korin, near my office in Tribeca.
The hardest thing for me to get my head around is how to maintain a 17 degree angle. If anyone has any tips, I'd really appreciate it. I'll dig into these links more when I get home, but really enjoyed the Scary Sharp story.
posted by staccato signals of constant information at 6:09 AM on July 11, 2017 [1 favorite]


I have been sharpening my knives with a steel and a stone, for the longest time. I sometimes get after it and get them really, really sharp, then Julia Childs myself. Then I just let the knives go back to where I basically beat up my vegetables in to recognizable shapes, and tear up meat into easily masticated small areas.
posted by Oyéah at 8:48 AM on July 11, 2017 [2 favorites]


I "scary sharped" all of my knives and tools once. Took some time. I got them all, even the planers, to pass the various tests and whatnot. They had mirror finishes and the edges gleamed in the light. Quite lovely.

The difficulty is that inadvertently brushing a tool, knife, whatever became an exercise in bleeding. I couldn't allow people to use my kitchen knives without warnings. My utensil drawer was a mass casualty drill in the waiting.

I have one scary sharp knife now. The rest are suitable for bludgeoning foodstuffs.

The mentions of diamond hones and other tools remind me of the epic flame wars over the pro/cons of such things vs. modern sandpaper. I am a sandpaper man m'self, and I'll spare you the lecture as to why.
posted by pdoege at 9:03 AM on July 11, 2017 [1 favorite]


The reason I think they are useful is because for many people, they simply work.

Well, the problem is that they simply work... for a little while. The fancy electric ones that basically grind the blade probably work fine forever, but the handheld ones seem to be more or less equivalent to using a honing steel. If your edge is a little bit off, it'll straighten it out. If your edge is just plain dull, it won't do anything and you need to whip out a set of stones. But when you get to that point, you won't necessarily know how to use the stones properly, because you haven't been practicing.

But, yeah, sharpening nerds will have you believe that they're some kind of sacrilege, which is ridiculous. It's just a tool with a different use case.
posted by tobascodagama at 9:17 AM on July 11, 2017


I got one of those cheap USB microscopes and have had a lot of fun looking at blades as I sharpen them. It hasn't changed anything about how I sharpen or the results, but it's cool to look at.
posted by OmieWise at 9:34 AM on July 11, 2017 [5 favorites]


pdoege:The difficulty is that inadvertently brushing a tool, knife, whatever became an exercise in bleeding. I couldn't allow people to use my kitchen knives without warnings. My utensil drawer was a mass casualty drill in the waiting.

"But sharp tools are safer!" ... say some people who clearly don't live the way the rest of us do.
posted by clawsoon at 10:42 AM on July 11, 2017


OmieWise: I got one of those cheap USB microscopes and have had a lot of fun looking at blades as I sharpen them. It hasn't changed anything about how I sharpen or the results, but it's cool to look at.

I got a 450x microscope off of Craigslist for $10 (manufacturer: Edu-Toy) to look at my blades. It has definitely reduced the time I spend rubbing back and forth, back and forth. Oh, look... it only took a few seconds for the entire surface to be covered in the scratch pattern of the grit I just changed to. Guess I can stop now.
posted by clawsoon at 10:45 AM on July 11, 2017 [4 favorites]


The only thing that beats the feeling of achieving a perfect edge on a fancy knife using the best tools is achieving a decent edge on a cheap knife using the sidewalk and the bottom of a coffee mug.

Get some cheap knives and practice on them. Next time you are at a house party where not a single knife is sharp enough to slice a lime without crushing it you'll be able to impress everyone with your skill.

And then you will never be invited again because you get a reputation as a knife nut.
posted by Dr. Curare at 2:00 PM on July 11, 2017 [6 favorites]


This conversation is both more eye opening and (so far) more polite than what I'm accustomed to on the woodworking forums/blogs I frequent.
posted by bonobothegreat at 2:29 PM on July 11, 2017


I've relied on raising a burr, especially for longer knives (chef knife, slicer), so that I know I've gotten a consistent result across the whole blade. Based on comments here I might start experimenting with alternative ways to check. Always room to get better!

Also: The difficulty is that inadvertently brushing a tool, knife, whatever became an exercise in bleeding. I couldn't allow people to use my kitchen knives without warnings. My utensil drawer was a mass casualty drill in the waiting.

Drawer?! Make the knife block your friend, to protect people and the knives.
posted by cubby at 9:10 AM on July 12, 2017 [1 favorite]


Nice timing, this thread. I've got a combination 400/1000 grit stone that works well, but I'd never felt like I fully grokked what was going on with burrs before. It helped me get a completely abused, relegated to scraping dirt from between floorboards knife back to paper cutting sharp this afternoon.

I'd be interested to hear any more mefites' tips on improving technique; I've never gotten to the point that you could shave hairs with a knife, though other sharpening threads have explained I should be able to, in certain terms.

Also, most of you have probably seen it before, but this paper has more electron microscope images of various sharpening processes, including burrs that have been pressed down by a steel on page 15.
posted by lucidium at 1:42 PM on July 13, 2017


I've got to say thanks for the links re the diamond stones. I have not been satisfied with the fine diamond plates I have, I've felt like my edges have not progressed on those grits, and have sometimes seemed to lose keenness. It really helps to know why.
posted by OmieWise at 5:48 AM on July 14, 2017 [2 favorites]


OmieWise: I have not been satisfied with the fine diamond plates I have, I've felt like my edges have not progressed on those grits, and have sometimes seemed to lose keenness. It really helps to know why.

One of the more insightful - if frustrating - comments that I've read on a forum where sharpening was being discussed was how many factors affect the impact of an abrasive on a blade. Substrate is one of those factors: Embedding tiny diamonds of uneven size in solid nickel is going to have a very different effect than spreading them in a paste over a soft leather strop.
posted by clawsoon at 4:43 PM on July 18, 2017 [2 favorites]


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