Questions About Sharpening

[rummels]

I have been using the 40degree side of a Sharpmaker to sharpen my kitchen knives and I can get them reasonably sharp with only 5-10 minutes work (I re-profiled them with a DMT coarse diamond stone). Note that when I say reasonably sharp, I mean that my knives will cut paper, but they will also sometimes catch on the paper when starting the cut or during the cut. I am confident that I have holding the knife at a consistent angle to the Sharpmaker’s rods.

I use a black marker on the edge of the knife, and a 20X loupe to make sure I am reaching the very apex of the knife’s edge, and to determine whether the scratch pattern on the surface of the edge is consistent.

I use the corners of the medium grit Sharpmaker rods for almost all of my sharpening, as I haven’t noticed any real improvement by moving on to the flats on the medium rods or by using the white rods. But I must admit that another reason I haven’t used the flats on the Sharpmaker’s rods is because it seems to be somewhat “tricky” to keep the angle of the blade against the rod correct while also trying to keep the blade “flat” against the relatively narrow flat surface of the rod.

It is important to note that I have never detected a burr on any knife I have sharpened or re-profiled, even when using something as aggressive as DMT coarse diamond stone. I have tried needles and fingernails and a 20X magnifying loupe and have never been able to detect a burr. Note that I have tried sharpening just one side of the blade for a while (20 -30 strokes) before checking for a burr.

My goal is to have knives with edges on them that are as sharp as possible, but that also do not dull quickly. I know that there are often trade-offs between a blade that is “scary sharp” and one with good edge retention. But I don’t want a knife that can just cut paper in an impressive manner. I want one that will cut wood, food, cardboard, etc without dulling quickly, assuming a high quality steel that provides reasonable good edge retention.

My folding knives are S30V, S35V and M390, but I haven’t had a need to sharpen them yet, and I don’t feel at all ready to take on those types of steels.

An example of the type of edge I would like to put on my knives is the edge that my Benchmade 761 came with. This knife will cut through a piece of paper almost without effort and it never snags or catches on the paper.

I should also mention that I am aware of some of the techniques use to remove burrs and wire edges and have tried some them, like Jeff Clark’s method for burrs. But I don’t know when to use these techniques because I am never sure if there is a burr there to begin with. I have not tried stropping.

This brings me to my first question. I understand that some knives are sharpened with a more “toothy” edge that allows them to cut more easily through materials such as cardboard and rope, verses knives being used to push-cut a fish while filleting it. I assume the type of edge that is on the 761 is the “toothy” type given the coarse scratch pattern on the 761’s bevel. But if this is the case, why do so many individuals who discuss sharpening knives on various forums indicate that you need to have a more refined edge to be able to cut paper easily? How does the 761 cut paper so easily while having such an obvious scratch pattern on the sides its bevel?

And why is it that I don’t find any improvement in my ability to slice a piece of paper if I use the fine rods provided with the Sharpmaker? My experience seems to be contrary to what most more experienced knife sharpeners observe. Which seems to be that is a knife that has a more polished (refined?) edge will cut paper more easily.

And could anyone help me understand why I can’t detect a burr, and what the best way to detect a burr might be? Or help understanding why I might not even be creating one?

I have read so many different and varying descriptions of how to sharpen a knife that it sometimes seems that sharpening knives is more art than science. But I know that in the end it is science. I need to learn how to see and understand what is happening to the edge of the knife as I use different techniques to re-profile, refine and debur it. Right now I feel like I am guessing.

Any help would be greatly appreciated.
Thanks!
Rummels

 

[Obsessed with Edges]

I have been using the 40degree side of a Sharpmaker to sharpen my kitchen knives and I can get them reasonably sharp with only 5-10 minutes work (I re-profiled them with a DMT coarse diamond stone). Note that when I say reasonably sharp, I mean that my knives will cut paper, but they will also sometimes catch on the paper when starting the cut or during the cut. I am confident that I have holding the knife at a consistent angle to the Sharpmaker’s rods.

I use a black marker on the edge of the knife, and a 20X loupe to make sure I am reaching the very apex of the knife’s edge, and to determine whether the scratch pattern on the surface of the edge is consistent.

I use the corners of the medium grit Sharpmaker rods for almost all of my sharpening, as I haven’t noticed any real improvement by moving on to the flats on the medium rods or by using the white rods. But I must admit that another reason I haven’t used the flats on the Sharpmaker’s rods is because it seems to be somewhat “tricky” to keep the angle of the blade against the rod correct while also trying to keep the blade “flat” against the relatively narrow flat surface of the rod.

It is important to note that I have never detected a burr on any knife I have sharpened or re-profiled, even when using something as aggressive as DMT coarse diamond stone. I have tried needles and fingernails and a 20X magnifying loupe and have never been able to detect a burr. Note that I have tried sharpening just one side of the blade for a while (20 -30 strokes) before checking for a burr.

My goal is to have knives with edges on them that are as sharp as possible, but that also do not dull quickly. I know that there are often trade-offs between a blade that is “scary sharp” and one with good edge retention. But I don’t want a knife that can just cut paper in an impressive manner. I want one that will cut wood, food, cardboard, etc without dulling quickly, assuming a high quality steel that provides reasonable good edge retention.

My folding knives are S30V, S35V and M390, but I haven’t had a need to sharpen them yet, and I don’t feel at all ready to take on those types of steels.

An example of the type of edge I would like to put on my knives is the edge that my Benchmade 761 came with. This knife will cut through a piece of paper almost without effort and it never snags or catches on the paper.

I should also mention that I am aware of some of the techniques use to remove burrs and wire edges and have tried some them, like Jeff Clark’s method for burrs. But I don’t know when to use these techniques because I am never sure if there is a burr there to begin with. I have not tried stropping.

This brings me to my first question. I understand that some knives are sharpened with a more “toothy” edge that allows them to cut more easily through materials such as cardboard and rope, verses knives being used to push-cut a fish while filleting it. I assume the type of edge that is on the 761 is the “toothy” type given the coarse scratch pattern on the 761’s bevel. But if this is the case, why do so many individuals who discuss sharpening knives on various forums indicate that you need to have a more refined edge to be able to cut paper easily? How does the 761 cut paper so easily while having such an obvious scratch pattern on the sides its bevel?

And why is it that I don’t find any improvement in my ability to slice a piece of paper if I use the fine rods provided with the Sharpmaker? My experience seems to be contrary to what most more experienced knife sharpeners observe. Which seems to be that is a knife that has a more polished (refined?) edge will cut paper more easily.

And could anyone help me understand why I can’t detect a burr, and what the best way to detect a burr might be? Or help understanding why I might not even be creating one?

I have read so many different and varying descriptions of how to sharpen a knife that it sometimes seems that sharpening knives is more art than science. But I know that in the end it is science. I need to learn how to see and understand what is happening to the edge of the knife as I use different techniques to re-profile, refine and deburr it. Right now I feel like I am guessing.

Any help would be greatly appreciated?
Thanks!
Rummels

Most of the bolded points seem to suggest you're not fully apexing the edge, more often than not. This is why you're not noticing much 'refinement' or change in cutting when going to a finer grit. It's also possible that some portions are apexed (with associated burring) and some aren't. The tearing/snagging/catching of the paper suggests at least some of that, which is to say there IS a burr on some of the edge, which is usually responsible for that 'snagging' when cutting paper.

When a full-length burr does form, it's generally obvious that it's there; either by sight, or by feeling it with the fingertips or nails, or by seeing how it's affecting cutting. The mention that you haven't been able to detect a burr likely suggests it's not quite 'there' yet; not fully apexed, and therefore the burr hasn't formed. The best value of the obvious and detectable burr is, it's the GUARANTEE that the apex is formed, as the burr won't form until it is apexed. If you're not seeing or otherwise detecting it, odds are it isn't there yet, and the edge isn't fully apexed, at least on the full length of the edge.

One doesn't need a more polished or more 'refined' edge to cut paper well. Only a full-length & crisp apex, free of burrs, is needed for that. In fact, a very coarse edge, such as that produced on a DMT 'coarse' hone, can be a viciously effortless paper-cutter, IF the edge is fully apexed and all the burrs have been cleaned up. Same is true of a fully apexed and burr-free mirror-polished edge; the difference will be in how quietly or smoothly the edge zips through the paper. A coarse, fully-apexed & clean edge will be more noisy, but still scary-effortless; a more highly-polished edge that's in equally clean condition will be just as effortless, but more 'whisper-quiet' in cutting paper.

Another note, which may seem a bit contradictory to those learning the process... you mentioned you haven't seen burrs on something like a coarse diamond hone. It's often possible that some steels won't burr that much on such a hone, so long as the pressure used is maintained very light. In my own uses, I've begun liking diamond hones for this reason, because when properly used with light pressure, they cut very, very cleanly and can leave minimal or nearly no burrs behind, requiring little stropping. By contrast, something as 'fine' as the Spyderco's ceramics can burr an edge much more easily, because they're both very smooth and very, very hard. It's very easy to roll or burr an edge on them, especially on the corners of the rods, which focus and magnify pressure. Pressure is what creates burrs, and also makes them bigger. With the Sharpmaker, I'd strongly suggest using the FLATS primarily, for this reason. Corners can be used also, but care must be exercised to scale back pressure while using them, maybe to 1/4-1/2 of the pressure used on the flats, or even lower. When using the SM, I constantly 'remind' myself to keep pressure just as light as if I were just brushing dust from the rods with the knife edge as I'm using them, and no heavier.


David

 

[rutcrazed]

Excellent post OWE. Great advice.

 

[rummels]

As rutcrazed said, this is excellent advice OWE, and I greatly appreciate your taking the time to help.

It appears that the gist of my problem is not working each side of the blade long enough to fully apex the edge and raise a burr. Given that I have been removing all of the black marker from the edge right down to the apex, is it possible to remove all the marker and still not raise a burr? Is there something else that I should be looking for when I use the 20X loupe other than removing all the marker?

Is there some "technique" or approach or stone that would work with the Sharpmaker that I could use in order to almost guarantee that I will create a burr? Not something that I would necessarily continue to do going forward, but at this point just something that would almost guarantee that I will raise a burr and then be able to detect it? Should I just keep using the corner of the brown (medium) Sharpmaker rods to purposely try to raise a burr, or is there some other rod I can buy for the Sharpmaker that would work better?

Assuming I have raised a burr on one side of the knife, and then raise a burr on the other, what is the simplest way for a beginner to remove the “final” burr that exists after apexing both sides of the blade? Again there are many approaches being suggested on the forum, but I would like to start with the simplest, most "sure-fire" approach if such an approach exists.

I really appreciate the help.
Rummels

 

[Bludgeon]

Rummels, take a old knife and continuously sharpen one side only on your most coarse stone until you get a burr. You will know when you get one. 20 strokes on a medium stone isn't going to do it. Then switch to the other side of the blade and do the same amount of strokes to even out the bevel. You need to get the diamond rods http://www2.knifecenter.com/item/SP204D/Spyderco-Triangle-Sharpmaker-Diamond-Rods-Set-of-2 for the Sharp Maker also because the medium rods will effectively take almost forever to apex an edge that needs a fair amount of steel removed. Use these rods to achieve your burr and then move to medium and fine. Use both the corners and floats of each rod, take your time with purposely drawn strokes and don't let your tip ride off the stone or you will be mastering tip repair next.

 

[Obsessed with Edges]

As rutcrazed said, this is excellent advice OWE, and I greatly appreciate your taking the time to help.

It appears that the gist of my problem is not working each side of the blade long enough to fully apex the edge and raise a burr. Given that I have been removing all of the black marker from the edge right down to the apex, is it possible to remove all the marker and still not raise a burr? Is there something else that I should be looking for when I use the 20X loupe other than removing all the marker?

I've never fully trusted relying on the Sharpie ink; it's too easy to remove it prematurely, before it truly indicates the edge is apexed. It's handy for indicating when you're close to apexing, but then it's time to start watching for the burr. With a 20X magnifier, if a burr were there, it should look HUGE; if you're still not seeing it at that magnification, it likely hasn't formed yet. Also need to make sure you've got very bright light, when using magnification over 3X-5X or so; a lot of detail gets lost at higher magnification, if the light isn't sufficiently bright. Higher mag loses much more light, so the light source needs to make up for that.

Is there some "technique" or approach or stone that would work with the Sharpmaker that I could use in order to almost guarantee that I will create a burr? Not something that I would necessarily continue to do going forward, but at this point just something that would almost guarantee that I will raise a burr and then be able to detect it? Should I just keep using the corner of the brown (medium) Sharpmaker rods to purposely try to raise a burr, or is there some other rod I can buy for the Sharpmaker that would work better?

Bludgeon's point earlier, about using an old knife (thin blade in simple, low-hardness steel is usually easiest) with a very coarse stone is a good training tip, to generate an obvious burr. You could also use something like some 220-600 grit wet/dry sandpaper over a hard backing (glass, stone/brick, hardwood), and 'strop' the blade aggressively on it. The only objective would be to form a BIG burr, so you can look at it (both by naked eye and under magnification), feel it with your fingertips and nails, and maybe even see how it impacts cutting performance on paper (would likely see a lot of slipping/snagging/tearing of the paper with a big burr).

Assuming I have raised a burr on one side of the knife, and then raise a burr on the other, what is the simplest way for a beginner to remove the “final” burr that exists after apexing both sides of the blade? Again there are many approaches being suggested on the forum, but I would like to start with the simplest, most "sure-fire" approach if such an approach exists.

I really appreciate the help.
Rummels

Once a burr is formed, it's good sharpening practice to start gently abrading it away on the stones, using much lighter strokes and perhaps a slightly elevated angle (slightly wider/more obtuse). This should be done very, very lightly, only a pass or two at a time; then re-check for the presence of the burr. Keep monitoring it as you go, with the magnifier and touch/feel tests, and cutting paper, to correlate those aspects with the reduction in size of the the burr. My own 'most reliable test' for burr reduction/removal is paper-cutting (phonebook pages); when the edge is fully apexed and burrs are completely cleaned up, the differences in cutting paper become obvious: the blade will zip through the paper with no slipping, no snagging or tearing, and it'll do it repeatedly. Taken one step further, if the edge is still cutting paper just as well after drawing it through the edge of a piece of hardwood (I like red oak for this), then you know it's in very good shape; that proves all the burr is removed and the underlying apex is stable and strong.

For clarification, which knife (steel type) are you currently having trouble with? I'm asking, because it can impact the nature & tendency of the edge to form a burr. Very high-wear steels are often more stubborn about it on relatively fine hones (vanadium carbides in the steel will really slow it down, on something like ceramics), and one would have to go much further and get much closer to apex, before an obvious burr finally forms. Other simpler & low-alloy steels, on the other hand, are usually much easier in generating burrs quickly.


David

 

[rummels]

Thanks to all for the great advice!
Rummels

 

[Bludgeon]

Thanks to all for the great advice!
Rummels

Keep us updated on your SM progress.

 

[rummels]

OWE
I am not sure what steel is in the Henckels knife that has been given me the most trouble. But it does have "Friodur" on the blade which I have learned means that the steel was ice-hardened (cryogenically treated) and is a stainless steel.

I have a very old (and I believe fairly soft) fixed blade hunting knife that I will work on to develop a burr. I have a DMT Coarse/Extra Coarse diamond stone that I can use. It is in the grit range you recommended. I will post again with the results.
Thanks
Rummels