The Razor Edge Book of Sharpening (1985) [pdf] | Hacker News Reader

The Razor Edge Book of Sharpening (1985) [pdf]

sharpeninghandbook.info

152 pointsdaverol48 comments

I happen to own a paper copy of this book, and as usual for sharpening books, they throw in a chapter on axes as an afterthought. Sharpening an ax is different enough from most other sharpening that you should get a specialized text for it. It's not that difficult or terribly specialized, but knife sharpeners always seem to want to apply the ideas of knife sharpening to axes, which isn't quite right all the time.

Two books I recommend for axes are "One Moving Part", the USFS ax manual, probably the best (only?) work that they ever did:

https://www.fs.usda.gov/t-d/pubs/pdfpubs/pdf18232812P/1823-2...

And "The Ax Book" by Dudley Cook, which you'll have to buy a paper copy of. (I don't suggest you round the corners of your axes as he suggests though)

The old USFS ax manual, "An Ax to Grind", even had a companion video which you can find on youtube, though if you're new to sharpening the instructions could be more clear IMO:

https://archive.org/details/an-ax-to-grind

https://m.youtube.com/watch?v=22tBYD-HMtA

The Ax Book by Dudley Cook is also in the Internet Archive

https://openlibrary.org/works/OL495023W/The_Ax_Book

So is "One Moving Part" https://openlibrary.org/works/OL36779701W/One_moving_part

Thank you for this, I have an el cheapo hatchet that needs attention.

I have been sharpening my own knives and tools for 45 years, and have been doing it in the same way since I was in my teens and my dad and I read some article (in Popular Science, maybe?) which Just Worked. My dad was a bit more patient than I have ever been and his edges always shaved hairs, dry. My edges are still quite good though.

Anyway Ima procrastinating today and saw this HN item and hesitated, oh no, have I been doing something wrong all these years? So in the spirit of never stop learning I bit the bullet and read it.

I didn't have to read far though. First came the don't use oil bit and then next the relief and the burr, and nope! Hooray, whatever we read back in the day was the equivalent of this. Maybe it was the same people, I remember a folksy tone.

The sad thing is in all those years none of the people of my acquaintance, with the exception of my daughter, have ever had any interest in sharpening/maintaining their knives, and if they do anything (most don't), it's an electric sharpener. I've passed through some home kitchen horror shows, and now if I know I'm going to be cooking in somebody else's kitchen, I bring my own knives, even internationally. Mandatory for AirBnBs. I remember reading up on packing a set of knives on a Thalys train and reading some worrying restrictions. But decided, well WTF to chefs do in France? I didn't get hassled, maybe I was lucky.

Anyway, even though I don't think I've ever converted anyone, I always encourage people to learn to sharpen/maintain their knives. I will usually haul a big DMT hone along with me on trips to home kitchens and do a quick repair job on the host's knives. Weirdly, quite a few people are very wary of sharp knives! Dull knives are what terrifies me...

In the spirit of the best camera is the one you have on you right now, this DMT hone fits on a keychain.

https://www.dmtsharp.com/sharpeners/pocket-sharpeners/mini-s...

I used to get by in a pinch with the bottom edge of a ceramic coffee cup but it’s nothing compared to having a properly flat and consistently abrasive stone on you. It struggles with anything longer than a steak knife but most times it’s a steak knife that needs licking up to an edge at the table of a well meaning but poorly equipped restaurant.

I keep meaning to impregnate the inside of my belt with diamond wax so that it too functions as a field strop, though it’s a bit harder to be subtle in taking one’s belt off in public.

So this is a late comment but I finally clicked the link because I am a DMT addict, and lordy that's a cool thing that looks like it will travel just fine.

Which do you find best for traveling? I travel with one of the big DMT fine hones but if I was resorting to something on my keychain maybe I want coarse? When I said I do a "quick repair" I meant I can't correct each knife with only a fine hone, but I can make them better. In that spirit maybe the optimal travel keychain hone size is coarse. Because I don't have all night, nobody else cares, and sharper is better than "prop knife", as another commenter mentioned.

Very cool about the ceramics, I had not thought of that but since we have many crafty ceramics we know their abrasive properties and once you are given the idea huh that's obvious. Thank you!

You got it in one, spot on. The coarse will put an edge on a blunt instrument but you won’t be able to strop it. The fine hone isn’t aggressive enough but will produce an edge you can strop to a razor. I carry both, with the coarse blue on my keychain.

Bringing a knife to an AirBNB or a sharpener is a must imo. I have yet to ever go to one where the knives aren’t essentially prop knives they’re so dull.

I've been sharpening knives for the past few years with https://chefschoice.com/products/chefschoice-prontopro-diamo...

As far as I can tell it works great and requires virtually no skill or knowledge.

The downside of those is that they a) don’t actually create a very sharp edge, but instead create a “toothy” edge that can’t push cut, but can slice decently, and b) remove a lot of material, and thus shorten the life of the knife.

They are really good for a normal person to get a knife sharper than they could ever wish for. I've given one to all my kids as it's the only method for them to keep their knives sharp. It's a great tool for an everyday household kitchen.

They do have downsides and are not the right tool if you are intent on spending time honing your skill, that's not their place.

I had this exact same dilemma on the thalys then I remembered they don't actually inspect anything because it's a fucking train. Here in the US is impossible to get six feet without your stuff being rifled through though.

Years ago, when I lived in Seattle, I remember meeting an old Japanese blacksmith. I found him when I was looking to buy some of the pull-style hand saws, but when I met him to pick up the wares, it turned into a bit of a social call.

He must've been around 80 or so, lived by himself in a house that was half home half workshop. Got into talking about saws and chisels and blades and sharpening, complete with a Mr.Miyagi-esque riddle of "what does it mean to cut something?"

I walked out of there having learned how to quickly and effectively sharpen a blade -- hold a steady angle consistent with the rough grind of the edge, push into the grain of the stone, and remove the burr. Seeing that in this book brought this memory back :)

Any tips to hold the angle steady?

Practice. It is one of those things like riding a bike that you have to put in the time and mess up at if you want to master. It might take an hour or two to get that first blade sharp but once you develop the skill it will become easy. The biggest thing is to pay attention to what you are doing, how you hold the blade and the movements you are making and how that affects the edge. Check the edge often and examine the marks left by the stone, nice straight parallel even grooving tells you things are as they should be; they will appear slightly curved and/or look as if they fade away if you are changing angle during the stroke. The marks will actually tell you everything you are doing wrong or right once you learn to read them and some purposeful and exaggerated 'mistakes' can be helpful in learning to read them.

He had different wedges of wood with angles matched to different plane irons -- the wood would slide on the table/bench while the edge of the blade would go over the stone. Holding the iron against the angled block seemed to keep the angle consistent.

Roll the blade forward until the oil/water squeezes out from under it. You’ll see that happen when the blade is flat. Check out Rex Krueger’s sharpening videos on YouTube to see this in action

1) Use a big knife for practice.

I can't tell you how difficult it was to sharpen my little paring knife accurately.

And then I tried on my big chef's knife, and it was soooo much easier to hold the angle properly.

2) Your knife doesn't need to be razor sharp

I see this all the time, but putting that good an edge on a functional knife is useless wankery (if you're shaving with a straight razor, this does not apply). Studies show that the edge dulls itself down almost immediately upon usage. The edge still works well, but it won't cut your hairs anymore.

you can buy guides to hold blades at a set angle

do not believe other answer that says to just "practice" - you cannot hope to steady a blade with sub-millimeter precision, you must secure it...if you are off by a fraction of a mm you are resetting the edge

This is nonsense. Every chef I know sharpens by hand and they get an insanely sharp edge.

Kitchen knives are a laughably low bar for sharpening and most chefs don't care because their knives are destroyed, damaged or stolen in short order anyway

In kitchens I have worked in, knives were delivered by a service once a week, no one wastes time honing. Those chefs showing off their $5k custom knives get them stolen by dishwashers, these are for home users only imho

Sharpening straight razors is where you actually learn how to hone

I think it depends on skill. I'm not great at sharpening, others get to razor sharp in seemingly no time with just a single stone.

Not everyone has time and a decent level of natural dexterity but it is possible, since people seem to do it.

Japanese saws were written about in one of the editions of the Whole Earth Catalog, which I had read back in the day. The WEC was on the front page of HN recently.

https://en.m.wikipedia.org/wiki/Japanese_saw

The metadata says this was digitized by the Internet Archive in 2016. There is a better scan of a better copy of the book at the Internet Archive's library:

https://archive.org/embed/razoredgebookofs0000jura

I don't know whether the book is still in print, but it's in stock at Amazon:

https://www.amazon.com/Razor-Edge-Book-Sharpening/dp/0966605...

I bought this book years ago, and found the information interesting and useful. But it's also a shill for their products. Annoyingly, I found the home jig for knives and chisels extremely fiddly. You have to adjust 4 separate set screws (allen screws) to install the jig (mount it on a knife or chisel), and you have to do it twice: once for the coarse stone and one for the fine stone. I eventually switched to EdgePro equipment for kitchen knives, and I use a Veritas system jig with an 'ordinary' diamond stone for chisels and plane blades in the shop.

https://scienceofsharp.com/ is a great contemporary source for how to sharpen stuff, and what that actually means under a microscope.

I love this. It's a book about craftsmanship and the philosophy of excellence and knife sharpening is almost incidental (it takes a while to find the part that actually says how to sharpen stuff).

This kind of trade craftsmanship is rare these days but the lessons apply to any kind of productive pursuit.

I have a Japanese whetstone and I've been practicing sharpening my knives and watching Youtube videos and I'm still terrible. It's a source of frustration because I'll watching butcher TikTok videos and the way they can slice through meat makes me extremely envious.

Any good Youtube videos in particular that can help me with this, as well as maintaining the sharpness for a long time?

Same here. Sometime it was working nicely, sometime not. I came to the conclusion that I was not sharpening often enough (maybe 1x/month) to be able to hone my skill properly and get the muscle required muscle memory. I finally got one of the sharpening stand contraption that hold the angle for you and it’s been a game changer. It is still very rewarding but without the frustration.

I learned a lot about sharpening principles from this one: https://youtu.be/EmyW8nFDLr4

It’s focused on sharpening woodworking tools but it’s the same ideas for knives

Not a bad read. Looks like it's got a lot of technique(s) and basics. Could probably use some updates on materials and tooling for higher end (modern/powder metallurgical) steels.

Knowing how to sharpen your tools is something just about everyone should learn. Almost all of us have at least a kitchen knofe that needs attention.

Nice. I learned this "at the knee" from my grandfather and father. A few things in no particular order... This skill takes practice, the sharpening systems only help to get the angle consistent; you'll be happier if you learn to do it without one, practice on knives and especially scissors you don't care too much about first, you'll need a few stones and probably end up with several before you find the ones that work best for you and your edges, razor-sharp is over-rated except for skinning, wood planes and chisels and it's harder to maintain; working-sharp is plenty.

Re your last point: There is some well researched material, along with scanning electron microscope images of edges, that says this is incorrect. When sharpening to say “working sharp” you leave a burr on the edge that can quickly be folded over, and reduce longevity of the sharpness of the edge. The most durable edges have been deburred to the true edge apex, and this often will give you an edge that would rate “razor sharp” or ~50 BESS on a sharpness tester. This has been proven out in a real life commercial setting, slaughterhouses. The edges that Dr. Kraichuk sharpened would stay sharp for 7 full carcasses, rather than 4-5 done with previous methods that can leave a burr on the blade.

For more information about this, including the proof with SEM photos and extensive testing via scientific method, check out the work of Dr. Vadim Kraichuk

https://www.amazon.com/Knife-Deburring-Science-behind-lastin...

There is a lot of discussion about this in the Tormek forums, where Dr. Kraichuk was a frequent contributor. I can attest to how well this works, every knife and woodworking tool in my house is hair splitting sharp, and they stay that way with little effort.

I don't disagree at all but this might be a problem with folk knowledge and terminology. I was taught to remove the burr or wire, you could feel it, and took it off with a steel or ceramic stick. My grandfather was a machinist and woodworker and I doubt he knew what the edge looked like. "razor" meant a pass with very high count fine (3k, 6k+) stones and maybe paste (I have green paste... I think it's Chromium Oxide ~45k) and leather strop. I'll do that for my straight razor, I don't for the kitchen knives.

I'm not going to break out references to everything in the Knife deburring book, but I'd advocate that anyone who wants proof of what I'm basically parroting back (with photos and sharpness tests, wear tests, and real world tests to back that up) read the book.

Once you've ground an edge, there may be a burr or wire that you can feel. Secondary honing brings that edge to something so fine, you can't see it or feel it, but it's not the edge apex. There is either a wire edge so small you can't see it, a feather edge, or a foil edge. These edges after honing may even pass sharpness tests, but will almost immediately roll and lose sharpness. This is exacerbated by the modern "super" steels and stainless steels that are used in knives today, and that is a whole other avenue of discussion.

For example, take a pretty bog standard Global kitchen knife. This is a high vanadium content stainless steel, so it should be ground with a diamond or CBN wheel. Sharpening with conventional abrasives will actually erode the substrate steel around the vanadium carbides in the blade, giving the edge a toothed appearance that eventually results in carbide breakout during use. Because these knives are an "in-between" burr forming steel (which means they don't necessarily form a positive burr or negative burr) and because the vanadium carbides need to be honed away with diamonds, the recommended method for honing this knife would be to sharpen 12 deg per side edge angle, progressing up to 1000 grit CBN or diamond wheel while grinding into the edge, then de-burr the edge with a slotted paper wheel at 5 micron diamond paste, then with felt wheel running away from the edge, impregnated with diamond spray at 1 micron, and +0.8 degrees edge angle. This will remove the wire edge and deburr the edge down to the root of the edge apex. Then hone with slotted paper wheel with Chromium Oxide (which is about grit level 60,000 or 0.5 micron) on a paper wheel for the last pass. This should read about 40 BESS on a tester, and a SEM photo will show no foil or feather edge. That is about 10-15 BESS sharper than a safety razor, but that is what is required to get rid of the different type of burrs that will cause the knife to dull quickly. These degrees are very precise, free-hand sharpening will not end up with the desired effect.

Anyway, not far off what your grandfather recommended, but somewhat different. According to Dr. Kraichuk's testing, leaving the knife more dull than 50-90 BESS almost always has an undesirable edge burr, be it foil, feather, or wire. This burr will roll over almost immediately under use, bringing the knife to a "working sharp" level of 300 BESS, which is pretty bad.

I can't really summarize this book in a HN comment, but if you're at all interested in this research, check out that book. You can get it on a PDF from the author's website, http://knifegrinders.com.au but the author died suddenly so don't look for any support.

> razor-sharp is over-rated except for skinning, wood planes and chisels

Razor-sharp is quite useful for razors. It's much safer to shave with a razor-sharp razor than a dull one.

Well, yes, and my straight razor is that sharp. Kitchen knives no and certainly not hatchets or axes.

Razor-sharp knives are safer to use than dull ones. Earlier today I was invited to a dinner by a family member, and she cut her finger, because, in her own words, she had to apply some force to cut an onion and she lost control of the knife (seriously, the f*king onion. It's ridiculous and I blame her husband for being lousy at sharpening). Cutting with razor-sharp knives requires almost zero force applied, which means you can focus on precision of movement, not strength.

Occasionally a newly sharpened knife when you've only seen dull ones can be dangerous too. If you have only ever encountered dull knives, you get used to the "press and wait til it breaks through and slams uncontrollably" to the point where you can mostly* get by, but you're not as used to safe handling when just getting ready to cut.

Sharp is still safer in general!

Or you can buy a jig like Spyderco Sharpmaker and have a razor-sharp edge in 5 minutes.

I find the Sharpmaker great for touching up an edge, but not nearly aggressive enough (without adding an aftermarket set of diamond rods) for repairing or setting a new edge

I used to own one, but I find the rods too short - it's good for small, 12-cm blades, but it's useless for anything bigger.

Right now I switched to proper water stones :)

this is basically the 2023 answer

I don't care if you are a fifteenth generation swordmaker who practiced for sixty years...you cannot hold a blade in your hands steadily, at sub-mm precision, for more than one stroke

changing the angle even slightly is effectively starting over

but if you must go old school - BELGIAN COTICULE...all other sharpening stones are inferior, it is no contest imho

>> you cannot hold a blade in your hands steadily, at sub-mm precision, for more than one stroke

That's what the guiding rails are for... So far whetstones with guiding rails are the best sharpening method I found. As you can see from my other comment in this sub-thread, I find Spyderco lacking.

This is FUD. If you believe this I have some $8000 speaker wire to sell you.

These are the methods I'm aware of:

-randomly swipe that long skinny thing that's in the knife block along a chef's knife, perhaps aiming for 45 degree angle -as a kid my dad had something I think he called a whet stone. He'd put 3-in-1 oil on it and we'd carefully swipe the blade against the stone.

Either of these right?

The first is a butchers steel, these were traditionally just a plain smooth steel rod which were used to repair the edge, shoving a knife through a joint tends to bend the very fine edge of the blade leaving what seems like a very dull spot. Essentially a heavy duty strop that would bend the edge back straight. These days they make them with abrasives embedded in the surface and are used to put a micro bevel on the knife, useful for the working chef but the home cook would be better off just sharpening the knife once or twice a month.

A whetstone is just a synonym for sharpening stone. The oil helps keep the removed particles of steel from getting embedded in the stone and clogging it. Water or oil is used with most types of sharpening stones for this purpose.

I think the long skinny thing is a hone. You use that after sharpening to hone the edge. But it won't make a dull edge sharp.

The whetstone sounds right. I think there's a lot of technique to how you swipe it, you can't just go in all guns blazing. But I don't know how to do it, so I'm not sure.

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