"Double-edging"

[Petunia D. Feeble]

I suspect the reason he stated this was because many modern steels can take and hold much thinner geometries than knives of years past without suffering from rolling or buckling. However, I'd offer the counterpoint that it means you can go thinner still with the relief angle for even greater improvement in performance. The old engineering conundrum with material advances: if a new material comes along that's twice as effective as the old, do you use the same amount to make it twice as resilient, or do you use half as much to make it just as resilient, but with less bulk? The answer depends on the context of the application, and is usually somewhere in between.

Absolutely. If we're only talking about two facets, a primary and secondary bevel, then modern steels can generally hold really low angles. The Endura that I carry almost every day has the primary set at about 10dps. Right now it's very slightly convexed at the apex from stropping, but when I need to touch it up on a stone it's just a couple quick strokes at about 15dps to create a micro-bevel.

 

[MtnHawk1]

idanp, I owe a lot to John Juranitch, the author of The Razor Edge Book of Sharpening. Before I read the book I was getting bits and pieces of good info online but didn't understand the whole concept. I am grateful that he demystified sharpening for me, and there is a lot of great info in the book.

I still basically sharpen this way, relief grinding at a very low angle so the edge, and above the edge, is as thin as possible. I don't think I've ever seen it argued that thick edges cut or chop better than thin edges. If a knife can't do what I want it to do with a thin edge then I don't want the knife. I usually have to pay more for this level of quality but it's worth it for the increased performance, durability, and confidence I get in a tool that my life, or others, could someday depend on.

The thing I like about a microbevel (what I call the second step in Juranitch's method; FortyTwoBlades would probably call it a macrobevel) is that if the edge is chipping or folding I can easily make it more durable simply by sharpening at a slightly higher angle. To save metal and time, I don't relief grind every time I sharpen, just touch up the microbevel when necessary. When this isn't enough, it means the edge is getting too thick and it's time to relief grind again (much less metal needs to be removed after the first time).

I think a lot of people don't relief grind because it can scratch the blade, but to me a knife is a working tool. I don't try to prevent or polish out scratches on my shovels, either.

Effective sharpening also greatly depends on what kind of knives you have, the steel they're made of, and what you use them for. There is a whole lot of variation within these factors, and Juranitch's method isn't the only one. Fortunately there are several wise and experienced knife sharpeners on this forum who generously share their knowledge, if you want to learn more.

 

[me2]

I learned basically the same method from Leonard Lee's book The Complete Guide To Sharpening. I decide the edge angle I want, typically 15 or 20 degrees. Most of my knives are 15 now. Then I grind a relief bevel 2 or 3 degrees lower, so 12 or 17. The relief is typically just done on my coarse or medium stones, which are a 220 grit Norton water stone or the coarse side of a Norton Economy combo stone. Then I micro bevel using either the Sharpmaker or the fine side of the Economy stone. I don't like the microbevel to be more than a shiny thin line along the edge, so I redo the relief grind every 2 or 3 sharpenings. Lately I've been sharpening much less than I used to, and have finally developed the control to use just the minimum number of passed to reset the relief. If I'm careful, I can go back to the coarse stone and each sharpening will remove about 0.0005" from the width of the blade. Yes, I did measure it.

 

[idanp]

idanp, I owe a lot to John Juranitch, the author of The Razor Edge Book of Sharpening. Before I read the book I was getting bits and pieces of good info online but didn't understand the whole concept. I am grateful that he demystified sharpening for me, and there is a lot of great info in the book.

I feel the same way. Watched a lot of videos online where they just show what they do without explaining it much and it really is a good textbook to get down both theory and practice. I've only started recently and get great results thanks to his clear and concise explanations (although I think the sketches and figures are bit confusing, but it is understandable considering the book was first published in 1985).

I don't think I've ever seen it argued that thick edges cut or chop better than thin edges.

I doubt this is true for cutting but for chopping I think the added weight behind the blade and the fact that a thicker blade would shove to the side the material being cut are intuitive reasonings (Juranitch gives the example of why you wouldn't use a flat blade to chop wood instead of an axe which makes a lot of sense to me).

The thing I like about a microbevel (what I call the second step in Juranitch's method; FortyTwoBlades would probably call it a macrobevel) is that if the edge is chipping or folding I can easily make it more durable simply by sharpening at a slightly higher angle. To save metal and time, I don't relief grind every time I sharpen, just touch up the microbevel when necessary. When this isn't enough, it means the edge is getting too thick and it's time to relief grind again (much less metal needs to be removed after the first time).

Thanks for the info. I think I will try this for a while too and see how it compares to without one. I also am going to experiment a bit with a magnifying glass to look for small chipping at a too steep of an angle without a microbevel.
Can I ask do you strop with a compound, and if so do you do it only on the final microbevel or both bevels?

I think a lot of people don't relief grind because it can scratch the blade, but to me a knife is a working tool. I don't try to prevent or polish out scratches on my shovels, either.

I agree, especially for large tools, but with cladding (or good imitations of) on good looking knives I think it is understandable. Although there are some ways to avoid scratching, other than taping I have found that using a waterstone and rinsing it and the knife frequently to dispose of the froth, along with not doing circular and/or back and forth motions (but only motions in one direction) pretty much eliminates scratches for me.

Effective sharpening also greatly depends on what kind of knives you have, the steel they're made of, and what you use them for. There is a whole lot of variation within these factors, and Juranitch's method isn't the only one.

I think this is part of what makes sharpness a very interesting topic

Fortunately there are several wise and experienced knife sharpeners on this forum who generously share their knowledge, if you want to learn more.

Thanks. This is something I really like about this forum

I learned basically the same method from Leonard Lee's book The Complete Guide To Sharpening. I decide the edge angle I want, typically 15 or 20 degrees. Most of my knives are 15 now. Then I grind a relief bevel 2 or 3 degrees lower, so 12 or 17. The relief is typically just done on my coarse or medium stones, which are a 220 grit Norton water stone or the coarse side of a Norton Economy combo stone. Then I micro bevel using either the Sharpmaker or the fine side of the Economy stone. I don't like the microbevel to be more than a shiny thin line along the edge, so I redo the relief grind every 2 or 3 sharpenings. Lately I've been sharpening much less than I used to, and have finally developed the control to use just the minimum number of passed to reset the relief. If I'm careful, I can go back to the coarse stone and each sharpening will remove about 0.0005" from the width of the blade. Yes, I did measure it.

Thanks for all the useful information. I think I will give the book a read as well; it seems to have a lot of good reviews too.

 

[me2]

Lee has some different perspectives than most on sharpening. He uses much lower edge angles. The book also is geared towards wood workers. It covers knives to adzes, 2 man saws, scrapers, draw knives, & everything in between. His recommended edge angles for dedicated tree felling axes are the same as most recommend for pocket knives now. However, he had the experience to make those recommendations, having spent Canadian winters felling trees with axes for heat. Sadly Lee has passed now.

The one criticism I had was the chapter on metallurgy, but it's very difficult to explain stuff like that in a 3 page chapter in a book about something else. What I did find very interesting was the section on various processes for hardening tools, such as induction, laser hardening, etc.

 

[afishhunter]

I still strive for perfection

With the possible exception of one's spouse, "perfection" does not exist in or upon this world. Least wise I ain't never seen it.

 

[BenchCo Spydermade]

I like to sharpen the entire bevel on a knife when I do heavier work with a power belt sharpener.

Then I use a sharpmaker at a slightly more obtuse angle to maintain it. The nature and weak point of the sharpening rods being slow and removing very little metal becomes a strength and it sharpens relatively quickly at the slightly larger angle. Easy to just run it down a few times before or after I use a knife.

When I begin to notice it taking too long on the rods or I'm not getting the edge I want anymore, back to the belt sharpening.

No reason to start with a microbevel tho, as far as I can see.

 

[MtnHawk1]

for chopping I think the added weight behind the blade and the fact that a thicker blade would shove to the side the material being cut are intuitive reasonings (Juranitch gives the example of why you wouldn't use a flat blade to chop wood instead of an axe which makes a lot of sense to me).

I agree, but I was actually writing about thin edges, and behind the edges, not thin blades.

I have some big wood-chopping knives (9.5" blade; .25" spine) that would definitely be considered thick when compared to smaller knives. I wanted to thin out their fairly thick factory convex edges but just to make sure I wasn't doing something I'd be sorry for later (the knives are fairly expensive), I did a lot of chopping to compare the original edge with a thinned-out edge. I mostly chop dead fir and pine, which can be very hard, with knots, so it's a tough test for knives, especially with thin edges. There was no doubt in my mind that the thin edge outperformed the thick edge by quite a bit, so I felt comfortable thinning them all out. Fortunately these thinner edges did not chip or roll (the knives are high-quality steel), but I put a microbevel on just to be on the safe side.

The sketches in Juranitch's book threw me off a bit when I first saw them, but once I realized how simple his sharpening concepts and instructions are they became much easier to understand.

It's good you are into experimenting with sharpening. That's a great way to learn and find out what works and what doesn't for your knives and uses. I'm also a believer in using magnification to evaluate sharpened edges. It's cool to actually see what I'm doing.

I'm not much into stropping and when I do it's just a couple of strokes across leather. No compounds. It's fairly easy to round off the apex when stropping and I like toothy edges. From what I know about stropping, which isn't much, it's more for smooth, refined, polished edges than toothy ones. There are many threads and posts about stropping on this forum and you'll find a wealth of information on the subject if you do a search.

It's still not easy for me to scratch fairly expensive knives, or remove their coatings, when I reprofile but I've always appreciated the wisdom in the saying "Function Over Form". I like good-looking knives, but value performance much more than appearance.

His recommended edge angles for dedicated tree felling axes are the same as most recommend for pocket knives now. However, he had the experience to make those recommendations, having spent Canadian winters felling trees with axes for heat.

I always respect those who actually try things out for themselves rather than just follow conventional "wisdom".

I am sorry to learn of Leonard Lee's passing.

 

[Sergeua]

With the possible exception of one's spouse, "perfection" does not exist in or upon this world. Least wise I ain't never seen it.

Still no reason to say f*** it