My sharpening technique: A polished edge that is coarse, best of both worlds

[yablanowitz]

How coarse a bevel are we talking about? 50 Grit belt? Coarser? The scratches left by my DMT Extra Coarse hone can be polished out with a microbevel .005" wide.

 

[Jason B.]

How you do your edge bevel has very little to do with how a knife can cut cheese. The main grind of the knife is usually the problem and the thiner the knife the better it will cut cheese. Knives like the zing or groove help with solving surface friction problems because of the desing of the main grind, its said to provide 80% less friction and proves this fact very well when cutting things like cheese or meat.

 

[Broos]

I've come to the opinion that the whole issue of slicing performance is extremely complex. Weighing against the benefit of slicing aggression you get with a coarser edge are the drawbacks of reduced cutting performance overall -- a slice is, after all, actually part slice and part push cut -- and reduced edge life/retention. So deciding on the optimal edge finish is going to depend on a whole bunch of factors, ranging from materials to be cut and just how they're going to be cut, to properties of the steel itself, and even unknowables like how long it will be until you'll be resharpening the blade.

So bottom line ... if it works for you, and gets the job done, that probably counts for 90% of the results you can expect. Until somebody really sorts it all out, that is.

Right on.

 

[cotdt]

How coarse a bevel are we talking about? 50 Grit belt? Coarser? The scratches left by my DMT Extra Coarse hone can be polished out with a microbevel .005" wide.

Yeah the coarser the better, 50 grit belt sounds good. 0.05" is 0.13mm, which can be beaten by putting on the smooth polished edge first (my 'reverse-microbevel' technique). Then you can take the width down to something arbitrarily small.

Side note: In theory 50 grit is 0.30mm, so I'm a bit skeptical that you can get rid of the scratch pattern with a microbevel that is only 0.13mm (0.05") wide. In my experience you need a significantly wide microbevel using the standard microbevel technique. Hence my technique reverses the order with the smooth edge created first.

How you do your edge bevel has very little to do with how a knife can cut cheese. The main grind of the knife is usually the problem and the thiner the knife the better it will cut cheese. Knives like the zing or groove help with solving surface friction problems because of the desing of the main grind, its said to provide 80% less friction and proves this fact very well when cutting things like cheese or meat.

Excellent point, but what if you're using a Scandi grind and the edge takes up more than half the blade? Then the edge and the main grind cannot really be considered separate.

 

[Jason B.]

True but scandi type knives work best at cutting wood not cheese.

 

[cotdt]

True but scandi type knives work best at cutting wood not cheese.

But why not BOTH? Have you ever thought about that!

:jerkit:

 

[zhangmaster12]

Why not just make a toothy edge like 320 or so grit, then strop? Im talking about belt sander grits / leather belt btw.

I find that this is amazing for food prep especially meat. Never tried it on non-kitchen knives, so no comment of woodworking.

 

[Dave Rishar]

I've read some material saying you could get a hair shaving edge with a 100 grit belt sander, but I don't have access to that equipment. I suspect that's more about a consistent and *thin* angle than a fine edge.

Back when I spent a lot more time on my belt sander than I do now, I used to show off by shaving leg hair with my splitting maul. I was using something around 100#. It may have actually been coarser, as I normally did my splitting in the driveway and the maul was pretty chipped up a lot of the time; consequently "sharpening" and "hogging" were synonymous in this case and I would've been using the coarsest belts I had around.

The edge does not have to be thin, but it does have to be consistent.

 

[cotdt]

Why not just make a toothy edge like 320 or so grit, then strop? Im talking about belt sander grits / leather belt btw.

I realize this is a common practice, but I don't really understand it. A strop contains no abrasives and no sharpening power. Its purpose is to realign the edge after use (or traditionally, right before the next use).

 

[zhangmaster12]

I realize this is a common practice, but I don't really understand it. A strop contains no abrasives and no sharpening power. Its purpose is to realign the edge after use (or traditionally, right before the next use).

yes it does have abrasive. its my fault I forgot to mention a loaded strop. D"oh!

 

[MVF]

Thanks for starting this thread. I've been wondering for a while which way to go (polish then rough it up or vice versa) to get this effect and have just been too lazy to try all the variations. Looking forward to seeing more discussion.

In the meantime, I've just done part of my edge polished and part coarse- how much of each and where determined by the knife and it's intended use. I'm surprised I haven't seen more of these discussions as handy as having the benefit of both edge types is.

 

[Jason B.]

But why not BOTH? Have you ever thought about that!

:jerkit:

How about pic's or it didn't happen

 

[yablanowitz]

Yeah the coarser the better, 50 grit belt sounds good. 0.05" is 0.13mm, which can be beaten by putting on the smooth polished edge first (my 'reverse-microbevel' technique). Then you can take the width down to something arbitrarily small.

Side note: In theory 50 grit is 0.30mm, so I'm a bit skeptical that you can get rid of the scratch pattern with a microbevel that is only 0.13mm (0.05") wide. In my experience you need a significantly wide microbevel using the standard microbevel technique. Hence my technique reverses the order with the smooth edge created first.

Now that we have established what your skill level and sharpening experience is, you might try actually reading the post you quoted.
1) I did not say I was using 50 grit for sharpening. I asked if you were.
2) I stated I was using DMT Extra coarse for setting back bevels, which is 60 micron.
3) If you are getting 0.15mm deep scratches from your 0.30mm abrasive, you are using way, way too much pressure when you sharpen (in my experience, which only spans forty-five years).
4) I said 0.005" wide microbevel, not 0.050". 0.050" is a secondary bevel, not a microbevel. I believe I may have mentioned that as well.

 

[cotdt]

Now that we have established what your skill level and sharpening experience is, you might try actually reading the post you quoted.
1) I did not say I was using 50 grit for sharpening. I asked if you were.

I would use 50 grit if I had it, but my coarsest stone is 120 grit. There is really no limit to how coarse a stone you could use if you started with the full-mirror polished edge, since the very edge itself would be left untouched.

2) I stated I was using DMT Extra coarse for setting back bevels, which is 60 micron.

Fair enough. That makes the 0.005" inch width microbevel make sense, but in theory you can get closer still by creating the polished edge first. That was my whole point. Not just theory actually, I can do some measurements with my 200x microscope when I get the time.

3) If you are getting 0.15mm deep scratches from your 0.30mm abrasive, you are using way, way too much pressure when you sharpen (in my experience, which only spans forty-five years).

For creating the initial bevel, you are supposed to use pressure to speed up the process. For the record I use "zero" pressure when the real sharpening process begins, using only the weight of the knife itself. I'm not sure what you're trying to get at. 0.15mm deep scratches from massive 0.30mm abrasive isn't that far-fetched. Never measured, but the deepest scratches should be in that ballpark.

4) I said 0.005" wide microbevel, not 0.050". 0.050" is a secondary bevel, not a microbevel. I believe I may have mentioned that as well.

Fair enough, that was my typo. Should have read 0.005" inches=0.13mm. I beleive this is around the smallest the naked eye could see. You'll still need a microscope to check for remaining scratches, if you want to claim that your edge is smooth. I don't see how the standard microbevel technique is any easier to apply, maybe a lil' quicker.

If I use your same DMT X Coarse for the main bevel, and manage to get a polished edge less wide than your 0.005" inches, would this prove to you that the order in creating the microbevel does matter? Because I know I can do it.

 

[Josh K]

But why not BOTH? Have you ever thought about that!

:jerkit:

Very mature use of the "jerkit" in MT&E.

I realize this is a common practice, but I don't really understand it. A strop contains no abrasives and no sharpening power. Its purpose is to realign the edge after use (or traditionally, right before the next use).

Everything is abrasive. Jeans, skin, leather, etc. If it will dull the edge, it is abrasive.

 

[Jason B.]

There is no such thing as realigning a edge, there is no teeth that bend and a steel does not make them stright again. A strop is ment to refine a already almost perfect edge. With compressed strop leather a natural abrasive is present but is very fine, too fine to be effective on a edge that has any sort of large burr. Applying abrasive compound like diamond paste or chromium oxide bring you the abrasive level you want while still keeping all the great effects of stropping on leather. Stropping on natural leather works but is best left for your barber to do, the edge is just too smooth for normal use.

 

[Dog of War]

That's basically the same idea, except in a typical microbevel you are putting on the polished edge after the coarse one, not before. This technique here puts on the polished edge first so that you can get the coarse sides really really close to the smooth edge.

In a microbevel, you need to remove a good amount of metal to remove the scratch pattern of the coarse grind (otherwise you won't acheive a smooth edge). So you end up not being able to get the coarse sides as close as possible to the smooth edge.

I probably should have been more specific ... by "not polished" relief/primary bevel I meant a medium grit finish, what you get with ~200-250 grit using light pressure. So the microbevel only takes 5-7 very, very light passes on fine ceramic, so small you can barely detect that it's there with the naked eye even examing under bright light. But it sounds like you're after a much coarser finish on the relief/primary, so a much larger microbevel would be needed -- to the point it wouldn't be a "micro"-bevel at all.

Right on.

Thanks, Broos. Part of what I enjoy about this hobby is that it's kind of like Hercules fighting the hydra: if you're being somewhat objective about it, you're probably raising two additional questions for every one you answer. Guarantees you'll never grow bored!

 

[cotdt]

There is no such thing as realigning a edge, there is no teeth that bend and a steel does not make them stright again. A strop is ment to refine a already almost perfect edge. With compressed strop leather a natural abrasive is present but is very fine, too fine to be effective on a edge that has any sort of large burr. Applying abrasive compound like diamond paste or chromium oxide bring you the abrasive level you want while still keeping all the great effects of stropping on leather. Stropping on natural leather works but is best left for your barber to do, the edge is just too smooth for normal use.

You were right about stropping removing metal. I checked the edge under a microscope after stropping, and to my surprise metal was actually removed. Stropping DOES remove metal, how interesting. Small microscopic chips on the edge were gone. I wonder how this works, there's no abrasives on the leather, nothing nearly hard enough to remove steel.

Next, I will try sharpening with water. I've seen how 10 million years of water have smoothed rocks in the river.

 

[crbauhs]

Im going to say get a slipjoint. They have 2 or more blades. Get one polished. Get one course. I just think that having 1 blade with both will work good, but it still seems to me as if the micro serrations from the course stone will wear and you will have a dull polished blade.

 

[bradefolums]

I wonder how this works, there's no abrasives on the leather, nothing nearly hard enough to remove steel.

The abrasives are silicates

I wonder how this works, there's no abrasives on the leather, nothing nearly hard enough to remove steel.

Next, I will try sharpening with water. I've seen how 10 million years of water have smoothed rocks in the river.

water only moved the rocks, the rocks rubbed themselves smooth against vegetable tanned leather that retains natural silicates which are abrasive