Is a bur actually needed?
- Thread starter asterik216
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Not that I'm aware of.
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Who knew that my 2nd post would become such a big thread on here.
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I usually sharpen without creating much of a burr. This is becaise when I get a new knife I just touch up the edge holding the sharpmaker rod in one hand, knife in the other. I do a stroke on one side of the blade then the other. Repeat a bunch of times. As I am only doing one stroke per side there isn't much burr formed. This works for touching up an edge that is already fairly sharp. I can make an edge that is just starting to go dull very sharp this way.
However my Inkosi became "and came"' quite dull. I tried and tried the above method and it was't getting sharp. It wasn't until I used the burr that I was able to get it sharp.
However my Inkosi became "and came"' quite dull. I tried and tried the above method and it was't getting sharp. It wasn't until I used the burr that I was able to get it sharp.
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The Scientific Method really has nothing to do with removing human influenced variables. It saddens me that the Scientific Method is so poorly understood. In fact, one of the keys to the Scientific Method is to avoid bias, such as the having the preconceived belief that bending a paperclip is a good analogy for what happens with stropping a foil edge.
I've always liked the image inserted below (borrowed from the wikipedia article).
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Hi,
What happens when you bend that golf club past 45 degrees? 90 degrees? 180 degrees? Repeatedly?
It breaks right?
Just like a burr when you bend it past 90 and keep bending it repeatedly?
Or a paperclip or coat hanger?
And the metal weakens past the bend/break point?
Isn't that what the paperclip/coathanger experiment is about?
To demonstrate to your own eyes plastic deformation , and that the damage extends beyond the point of bend/break.
Again it depends on the thickness, as explained by the diagram. A 0.1 micron thick foil will not break off by stropping it on clean leather, but it will prevent the blade from shaving.
I can't break aluminum food wrap by bending it back and forth, can you?
(not sure if you know those are my "pictures").
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In this context the human influenced variable is going to be THE toughest factor to control for. We may very well have observable phenomena and a hypothesis, but the phenomena are all human generated.
The scientific method starts when you ask a question about something that you observe
To my way of thinking, any activity in this direction starts with a large sample group to see if there even is an observable phenomena that survives the first attempt to create some controls.
The scientific method starts when you ask a question about something that you observe
To my way of thinking, any activity in this direction starts with a large sample group to see if there even is an observable phenomena that survives the first attempt to create some controls.
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AT THE SAME TIME, it also requires that you are open-minded enough to accept that the answer may contradict your prior understanding.
In fact, a "large sample group" is not required. There are many cases where a single measurement can disprove the existing theory.
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In some cases I agree 100%, but in this case how do you rule out operator bias? Eg, I'm good at removing the burr, someone else might not be. Our results might directly contradict each other. You need to begin with a simple observable phenomena or hypothesis predicated on producing same, or you can't have an experiment.
This is especially critical in a situation where the hypothesis includes factors that are only detectable by inference - the edge dulls more rapidly due to unseen influences.
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A seemingly intractable problem can usually be broken down into smaller tractable problems. In the Scientific Method, we approach these tractable problems individually and slowly build an understanding that illuminates the larger problem.
In this case, you were following the Scientific Method by attempting to replicate Cliff's experiment/result until you were unable to replicate his findings. One possibility is to have a large sample of people attempt to replicate the experiment; however, what if there is a determining (and easily controlled) variable that we aren't aware of... then some will replicate the result and the rest will not. However, if all those people follow the Scientific Method and report all the details of sharpening we may be able to see what those two groups have done differently and identify that variable.
Another possibility is to be smart/lucky and hypothesize what that variable may be.... Then we can design a simple experiment to test the impact of that variable. For example, I know Cliff sharpens at extremely low angles. I also know that blades sharpened very low angles (eg less than 20 degrees inclusive) do not respond to micro-bevelling (straight razors, for example). What happens is that the apex bends away rather than abrading. For this reason, a technique that can successfully remove a burr on a 23 degree (inclusive) blade may not work on 17 degree (inclusive) blade.
In this case, you were following the Scientific Method by attempting to replicate Cliff's experiment/result until you were unable to replicate his findings. One possibility is to have a large sample of people attempt to replicate the experiment; however, what if there is a determining (and easily controlled) variable that we aren't aware of... then some will replicate the result and the rest will not. However, if all those people follow the Scientific Method and report all the details of sharpening we may be able to see what those two groups have done differently and identify that variable.
Another possibility is to be smart/lucky and hypothesize what that variable may be.... Then we can design a simple experiment to test the impact of that variable. For example, I know Cliff sharpens at extremely low angles. I also know that blades sharpened very low angles (eg less than 20 degrees inclusive) do not respond to micro-bevelling (straight razors, for example). What happens is that the apex bends away rather than abrading. For this reason, a technique that can successfully remove a burr on a 23 degree (inclusive) blade may not work on 17 degree (inclusive) blade.
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Thank you for the wikipedia 101, science cut/paste, but we're a little beyond the fun powerpoint slide. Why did I bother with a math/comp sci degree? It saddens me that internet forums are chock full of such passive-aggressive fodder.
The human influence is easily removed from this equation, you build a fully automated machine that the knife is attached to and all mechanical movements are tightly controlled by said machine. Then the control set is more tightly controlled and the dataset size required can be significantly reduced and the results can be viewed with a higher level of trust. Increasing the sample size, while providing more valuable data, is also a direct way of attempting to account for an uncontrollable human variable. There is no need to attempt to identify that variable (the unreliability of human mechanical movement) as we already have, just remove it before you even start the experiment. Until you accurately measure the exact angle of every manual stroke he takes his data is relatively 'unreliable' and it cannot be definitely said his results and method were accurately replicated.
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No offense, but you'd need to crowdfund the manufacture of such a device, it wouldn't be cheap. And...the critical aspect of when to stop and shift angles, or how much of a burr to make, how much force applied when the burr is formed, how to determine if the "burrless" method was truly burrless, how to decide when the burr is sufficiently removed to proceed - all of these are still largely subjective. At the least you'd need a panel of inspectors to decide when the machine was done with any given phase, and that would still add some democratic subjectivity.
And then you need a test sufficiently sensitive enough that the margin of error is much smaller than any change resulting from the various methods used (you would have to establish a baseline using the sharpening machine to guarantee any sort of confidence). Anecdotally, it takes a change of several points on a Rockwell C scale to see a difference with the same steel in terms of retention, all else being equal. Anyone claiming one method or another has that level of influence is welcome to their opinion. From my POV doing the sort of legwork needed to make a convincing argument is another story - I haven't seen it and frankly don't expect to.
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I was speaking strictly theoretical, in response to ToddS and his snarky little love note.
In a perfect world such machine would exist, I sure as hell wasn't suggesting one SHOULD be built nor that it's remotely realistic for this topic. Again, strictly theoretical, in a perfect experimental environment (and world) all of those factors, circumstances, situations and variables you mentioned would have a decent measure of control and our data sets would be virtually infinitely large to squash statistical anomalies... in a perfect world...
In the context of this thread I am siding with you. I'm not convinced creating a burr is a significant negative factor.
Completely removing the human influence from a tool directly manipulated by humans doesnt provide an accurate representation of the tools overall performance.
A burr isn't necessary, but a sharp blade with burr based sharpening is better than a dull one from trying to avoid a burr. I sharpen with or without a burr, depending on the knife and steel.
A burr isn't necessary, but a sharp blade with burr based sharpening is better than a dull one from trying to avoid a burr. I sharpen with or without a burr, depending on the knife and steel.
How can one detect that without magnification? Ive sharpened a couple knives that low and didn't detect anything to indicate that was happening.
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This entire thread, multiple pages, is literally a full on discussion/debate about the line "A burr isn't necessary, but a sharp blade with burr based sharpening is better than a dull one from trying to avoid a burr." The difference between your post and yours is: previous posters have provided support for their arguments, in many different forms; no offense to you is intended. Have you read through the entire thread, digested both sides of the arguments presented and looked at the plethora of citations, links, and pictures? There are many pictures of highly magnified blade edges in different stages and states. Take a look, read, observe, then come on back and join in the fun!
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I can't give a general answer to that, particularly for burrs that are too fine to feel with your finger. It's going to depend on how you finish your blade - for example a 20 DPS micro bevel with a DMT EF should easily deal with the burr on a 8 DPS sharpened apex. On the other hand, micro-beveling with a Shapton 16k at 10DPS will be very challenging.
Also, it depends on whether you are trying to produce a refined, push-cutting edge, or an aggressive slicing edge. The apex formed by breaking off a burr can be a very nice aggressive draw-cutting edge.
There are a couple of examples here: https://scienceofsharp.wordpress.com/2015/10/30/burr-removal-part-1/
I have read the whole thread and understand the pros and cons of burr based and non burr based sharpening. Picking a side seems a bit silly. I was simply answering the title question.
Forming a burr is not necessary, but if one finds it easier to sharpen by forming one, a sharp knife is better than a dull one. For steels that form a tenacious burr, burr based sharpening makes it more difficult, and knowing how to sharpen without forming one permits use of those steels without special/involved burr removal procedures.
That is interesting. It's it possible the larger increase in microbevel angle (8 to 20) causes greater lateral forces? I typically use small increases, 3 degrees or so. It's just enough to get beyond any sloppiness in the formation of the main bevel and ensure only honing/finishing the edge.
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