The Razor Edge Book of Sharpening

People have manually sharpened knives for well over a thousand years.
 
Twindog said:
The photo on the right is someone freehanding a 15 dps edge. They get one side at 17 degrees and the other side at 13 degrees. And their stone gets a bit off a couple other places. The difference between the distance at the edge shoulder between a 15 and 17 degree edge is just 0.004 inches on a 0.1 inch edge height. Four thousandths of an inch. Not many people can hold a stone to that precision.
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If I’m picturing your geometry correctly, you don’t have to hold 4 thousandths at the edge. You can hold 10 thou or so at the spine gap fairly easily. I don’t think people will waver 4 degrees on the same side of the knife.

Anybody ever show you the quarter trick? Measure your blade into 1/2” increments, spine to edge. Stack that many quarters (add a dime for a half increment) on one end of your stone and rest the spine on them. That’ll be your angle for about 16 per side, or 32 inclusive. That’s gonna vary a little with stock thickness and grind.

If you scrub a lot of strokes on one side, then flip over, gauge your angle on the other side and scrub about the same number of strokes, I can see where you might drop or rise some and not get your sides exactly equal. Perhaps less of an issue if you alternate strokes. But as you say, it’ll still get sharp enough to cut. If the imbalance bothers you, inspect it against a light colored background and see which side to favor to compensate.

Or, get used to cutting with a chisel grind and sidestep the entire balance issue.

In a way, Utubers do beginners a disservice when they brag about their perfect symmetry. I say, beginning sharpeners can produce ugly edges that are sharp enough to skin a carcass, slice meat and tomatoes, trim your toenails, scrape old gasket debris off a Chevy thermostat housing, and perform hundreds of other knife tasks adequately. Maybe don’t do all those tasks with the same knife (but know you could). Beautiful edges are a luxury. Edges that will cut things are easily obtained, with a little practice.

You’re gonna dull it. Sharpen it again. Study the process. It’ll get more familiar with time. But the good news is, you no longer have to suffer with dullness or find somebody to sharpen for you. It’s a learnable skill, cheap to start out, and it empowers you to cut your own stuff. Win-win-win.

Parker
 
Twindog said:
Here's why I think it's so difficult for someone to learn to freehand sharpen.

The photo on the left is a 15 dps edge done with a Wicked Edge. It's dead on.

The photo on the right is someone freehanding a 15 dps edge. They get one side at 17 degrees and the other side at 13 degrees. And their stone gets a bit off a couple other places. The difference between the distance at the edge shoulder between a 15 and 17 degree edge is just 0.004 inches on a 0.1 inch edge height. Four thousandths of an inch. Not many people can hold a stone to that precision.

The freehand edge is still sharp. Probably cuts as well. But the edge is not symmetrical. One shoulder is a bit higher than the other. The edge starts to get off center. The apex moves up into the blade a bit. Not a lot, but over time, it becomes a problem. And more metal is removed off the freehand edge. I'd expect this difference to be someone who has a lot of muscle/brain memory. A person new to sharpening will be worse that what is shown.

2v2aGiJnvxAWtWs.jpg
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I once read a well known knifemaker address this issue.He said that symmetrical edges are ,of course,best but asymmetrical edges can still be very sharp.
 
Yes, as Parker said, there are lots of hacks to get the freehand angle pretty close. And if you've been sharpening for years and doing it a lot, you won't need a hack.

And as Robert said, and my diagram shows, a freehand edge can still be very sharp and cut just fine.

I believe I mentioned all that. I'm just addressing the issues that freehand beginner sharpeners face, where they cannot get a optimal edge profile and where they can easily dull or weaken the edge performance with a slight wobble or tiny misplacement of a stone,. But someone with a bit of instruction can get a near perfect edge without going through all those hacks and without spending years getting their muscle/brain memory down.

Bill is correct that people have been manually sharpening edges for a long, long time. When I was a kid, I was taught to use an oil stone freehand. I was taught nothing about raising and removing a burr. Nothing about the importance of holding a consistent edge. I was a kid with little patience. And I could get a good, workable edge every time.

With modern stones and a good guided system, an ability to cleanly remove the burr and a proficiency at stropping an already clean sharp edge, my knives are much sharper than then used to be. And much sharper than any knife I experienced as a kid.

A well-known knife maker showed me that the key to a great edge is not just how sharp the apex is, but how long that apex profile and that edge performance lasts under load.
 
I just got the book and am reading it. Pretty good so far, although dated. (No known methods of testing steels of their ability to either take or hold an edge.)

The author says sharpening is not simple and the field is full of "old wives' tales and gimmickry." When he went into butcher shops, he found that only about 1 in 20 butchers could sharpen their knives properly, despite daily practice.

He also takes positions that a lot of people on this forum will not like, such as stainless steel edges lasting a lot longer than high-carbon steel edges.

And he takes down another sacred cow, saying that edges with teeth (coarse sharpening) do not last as long as a properly sharpened edge, which is smooth without teeth.
 
Twindog said:
I just got the book and am reading it. Pretty good so far, although dated. (No known methods of testing steels of their ability to either take or hold an edge.)

The author says sharpening is not simple and the field is full of "old wives' tales and gimmickry." When he went into butcher shops, he found that only about 1 in 20 butchers could sharpen their knives properly, despite daily practice.

He also takes positions that a lot of people on this forum will not like, such as stainless steel edges lasting a lot longer than high-carbon steel edges.

And he takes down another sacred cow, saying that edges with teeth (coarse sharpening) do not last as long as a properly sharpened edge, which is smooth without teeth.
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Knife Engineering, by Dr. Larrin Thomas is a more modern book and has a lot of info on steels and edges.
 
000Robert said:
Knife Engineering, by Dr. Larrin Thomas is a more modern book and has a lot of info on steels and edges.
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That may be. I haven't read Larrin's book yet. I'm just commenting on John Juranitch's book, because that's what this thread is about.

My sharpening skills are pretty well set, but hopefully I can pick up some good tips from The Razor Edge Book of Sharpening, which was decades in the making.
 
Twindog said:
That may be. I haven't read Larrin's book yet. I'm just commenting on John Juranitch's book, because that's what this thread is about.

My sharpening skills are pretty well set, but hopefully I can pick up some good tips from The Razor Edge Book of Sharpening, which was decades in the making.
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I thought that it was interesting and I learned some from it.
 
Twindog said:
Here's why I think it's so difficult for someone to learn to freehand sharpen.

The photo on the left is a 15 dps edge done with a Wicked Edge. It's dead on.

The photo on the right is someone freehanding a 15 dps edge. They get one side at 17 degrees and the other side at 13 degrees. And their stone gets a bit off a couple other places. The difference between the distance at the edge shoulder between a 15 and 17 degree edge is just 0.004 inches on a 0.1 inch edge height. Four thousandths of an inch. Not many people can hold a stone to that precision.

The freehand edge is still sharp. Probably cuts as well. But the edge is not symmetrical. One shoulder is a bit higher than the other. The edge starts to get off center. The apex moves up into the blade a bit. Not a lot, but over time, it becomes a problem. And more metal is removed off the freehand edge. I'd expect this difference to be someone who has a lot of muscle/brain memory. A person new to sharpening will be worse that what is shown.

2v2aGiJnvxAWtWs.jpg
Click to expand...
This is why he recommends frequent thinning of the edge at a lower angle before final edging.
 
That book helped me understand the basics and move from inconsistency to consistency in my sharpening. Any time I find my edge is off and Im not getting good results it is when I deviate or try something different when sharpening, For me it was very helpful reading that book.
 
ricklee4570 said:
Excellent book. I stopped using oil on my stones after reading this book!
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He is right about slurry being detrimental to an apex, but he is wrong about using oil and its effects. On hard stones that don't self slurry oil might make the stone act a little finer and on some stones make them faster as well. On softer stones you might see a bump in sharpness dry.
Had he not been sharpening in a mud of grime I think the oil would have given him a better edge but maybe not toothy enough for the meat packing company.

Thats as far into the book as I got just skipping through. Probably as far as I will go.
 
garry3 said:
He is right about slurry being detrimental to an apex, but he is wrong about using oil and its effects. On hard stones that don't self slurry oil might make the stone act a little finer and on some stones make them faster as well. On softer stones you might see a bump in sharpness dry.
Had he not been sharpening in a mud of grime I think the oil would have given him a better edge but maybe not toothy enough for the meat packing company.

Thats as far into the book as I got just skipping through. Probably as far as I will go.
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You missed the part where he says a toothy edge is inferior to a smooth, polished edge, even in the meat industry.
 
garry3 said:
He is right about slurry being detrimental to an apex, but he is wrong about using oil and its effects. On hard stones that don't self slurry oil might make the stone act a little finer and on some stones make them faster as well. On softer stones you might see a bump in sharpness dry.
Had he not been sharpening in a mud of grime I think the oil would have given him a better edge but maybe not toothy enough for the meat packing company.

Thats as far into the book as I got just skipping through. Probably as far as I will go.
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I'm hardheaded - I pretty much do as I please. My "oilstones" get oil on them and I really don't care what someone else says. I was taught that the oil was mainly to keep the stones clean by keeping the metal and junk from clogging the pores of the stones. I use soapy water with my diamond stones.
 
Twindog said:
You missed the part where he says a toothy edge is inferior to a smooth, polished edge, even in the meat industry.
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It's interesting that he didn't polish the edges for the meat packers.
I wonder if he feels the same way about fillet knifes?
 
I've had it and the stones that kind of went with it for years.. Have to think very few people *HERE* would benefit from it unless they don't mind laying their knives down on the stones and being ok with scratching the living hell out of them. IIRC he mostly concentrated on meat packing plants/knives for the book.
 
OilMan said:
I've had it and the stones that kind of went with it for years.. Have to think very few people *HERE* would benefit from it unless they don't mind laying their knives down on the stones and being ok with scratching the living hell out of them. IIRC he mostly concentrated on meat packing plants/knives for the book.
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You had the Razors Edge stones? Thoughts on the fine compared to other fine stones? Ive used a fine India and a Hard Arkansas and the jump in keenest was big between them, wonder where their hones fall in.
 
I did have the stones and guide but only used them once because they wanted you to lay the guide on the stone too but that ground metal off of the guide itself.. Gave the stones/guide away after that IIRC but kept the book for basics. And I didn't have any garbage knives that I wanted scratched to hell to get maximum performance..
 
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