Micro bevels as a method to deburr.

[Nullity]

The problem with this discussion is that we talk as though we’re flipping the burr back and forth. Actually, we’re cutting off the old burr while creating a new burr on the other side (right side diagram). It seems as though the burr is being flipped, but it’s actually a new burr. And it’s a new burr whether we increase the angle (to create a microbevel) or keep the sharpening angle the same.

Anytime a stone is scraped across the apex of a steel edge, a burr will form on the opposite side of the edge (left side diagram). The size of the burr depends on the coarseness of the stone and the pressure we put on that stone (and the type and hardness of the steel).

A microbevel creates its own new burr. The way to remove the burr is to decrease pressure on the stone and progress to finer and finer grits. A final stropping with 0.5 micron paste will remove any meaningful portion of the burr that is left .

Do you have any reputable sources to back up this theory?

 

[Jason B.]

Do you have any reputable sources to back up this theory?

It's not theory its fact.

A burr is debris from the side being ground, it does flip or break off as sometimes described but is re-created by new grinding which crosses the apex. The only way to "remove" the burr is to not create one.

 

[Nullity]

It's not theory its fact.

Got any proof or literature that supports that?
I know I've observed a large burr that flipped from one side to the other.
I'm sure of it because there's no way I formed a burr of that size during the few, low-pressure strokes on the opposite side.

Perhaps different sharpening methods create burrs differently.

 

[Jason B.]

I bid you good luck in finding such writings.

I have studied the edge in many stages under a microscope though and have a great deal of sharpening experience and a above average understanding for what happens during the sharpening process.

There are far to many variables in what you said to make any conclusion to why you observed the burr formation you did.

Different methods not really, unless you start talking about powered sharpening. For hand sharpening the one thing than can change the size of burr formation besides pressure is the abrasive type used.

 

[Nullity]

I bid you good luck in finding such writings.

I have studied the edge in many stages under a microscope though and have a great deal of sharpening experience and a above average understanding for what happens during the sharpening process.

There are far to many variables in what you said to make any conclusion to why you observed the burr formation you did.

Different methods not really, unless you start talking about powered sharpening. For hand sharpening the one thing than can change the size of burr formation besides pressure is the abrasive type used.

I only have my assumptions based on my observations. Perhaps some of the burr is removed when switching sides, but complete burr removal is not so trivial as one stroke on the opposite side.
I didn't claim my theory as "fact". The burden of proof is on you.

 

[Jason B.]

I guess my best "proof" is in the pictures. If I did not fully understand the process I would not be able to consistently produce those results or even begin to explain them.


Technically you can remove the burr in just one pass and I have done so on many occasions. Again, its a understanding of the process and how you apply it in sharpening.

Near the end of this video while on the 6k stone I do a single pass burr removal, I even make mention of it.
http://www.youtube.com/watch?v=TkLRoG9axDo

 

[Nullity]

I guess my best "proof" is in the pictures. If I did not fully understand the process I would not be able to consistently produce those results or even begin to explain them.


Technically you can remove the burr in just one pass and I have done so on many occasions. Again, its a understanding of the process and how you apply it in sharpening.

Near the end of this video while on the 6k stone I do a single pass burr removal, I even make mention of it.
http://www.youtube.com/watch?v=TkLRoG9axDo

Have you noticed the same easy, one stroke burr removal at the lower grits, say 100-300grit?

 

[HeavyHanded]

It is entirely possible to "flip" a burr, it can be done on hardwood or on any other sufficiently hard surface. Much of the time we forget that our stones aren't just abrasive, they are quite hard by most standards, more than hard enough to manipulate a very thin piece of unsupported steel. I have no doubt the burr can be recreated on the opposite side an instant after its been eliminated. But IMHO, in most cases when a burr seems to "flip" side to side its because that's exactly what's happening.

A burr can be flipped on a hard strop, lapping board, edge of a cutting board, surface a smooth granite countertop, piece of glass - in short, on all manner of surfaces that lack abrasive potential to create one in the first place. The burr isn't created on one side of the bevel, its created at the apex even if it starts out leaning to one side. Once there, there is nothing keeping it from flopping about on its attachment point.

Of course all the usual disclaimers re burr formation on high RC steels and other factors still apply.

The burr has to be worked off with enough pressure to allow the abrasive to do its job, but less than it takes to flip it - if there is some factor more proven than this I cannot imagine what it is.

Coming at it from a steeper angle such as when microbevelling, whether for a finishing technique or to reduce a larger burr in the course of creating a single bevel cutting edge, will cause more of it to be caught by the abrasive. One can also backdrag the edge along hardwood or similar and this will in turn, stand the burr up. Essentially changing the angle of the burr on the abrasive surface, rather than changing the angle of the apex to the abrasive surface. All these approaches do is allow increased pressure to be used so the burr gets dragged under the apex and ground off easier - they reduce the likelihood of the burr being pushed over the apex. Removal can still be done at the base formation angle as long as light pressure is used with an appropriate abrasive - takes a small increase in observation and grind time.

 

[Nullity]

HeavyHanded's post mirrors my thoughts on the subject, except explained infinitely better.

 

[HeavyHanded]

HeavyHanded's post mirrors my thoughts on the subject, except explained infinitely better.

Thank you sir. I am passionate about burrs and their controlled removal. IMHO this is 80% of quality sharpening - effectively controlling the sculpting process at the apex. I agree with many of the above sentiments re burrs forming anytime a stone crosses an apex etc. The best way to remove them is to grind them off, stopping at the point where one has reached the flat of the cutting edge - any further and a new one might form. This leaves only the amount of unsupported metal that might fit within the grind pattern and technically within the borders of the apex - so technically not really a burr?

Even with light pressure, if one continuously works one side of a bevel on a stone, a burr will form. The way to remove it is to treat it as a separate part of the cutting edge and grind it off in detail. This is why I'm a big proponent of sharpening the blade in sections if necessary - there may or may not be a burr along the entire length.

All talk of burrs is relative, as different abrasives on different backings, with varying amounts of fixation, will all attack the steel at the apex differently. There is quite a shift in dynamics going from a grinding stone, to sandpaper, to a lapping operation, to stropping, and there are examples of actions that use multiple mechanisms to some extent. I try to limit myself to the context of a hard stone when talking about burrs as this is something I feel very confident in my observations. When it comes to lapping, stropping, working with loose abrasives, muds, slurries, I'm in more of a theoretical mode. I still have strong opinions, but am much less ready to assert them, and much more ready to admit they might be mistaken or at least unprovable.

 

[Twindog]

Burrs are extremely weak, wire edges that are easy to remove. Many people just run their edge through cork or felt to remove them. The problem most people face is recreating a new burr while removing the old burr.

Imagine continually sharpening a blade with a coarse stone. You can keep going until the blade is worn out. And you say, "I just couldn't get rid of that burr; it just kept flipping from side to side." Actually, it's not the same burr. You got rid of burr after burr, but kept recreating a new burr. Do you really think it's the same metal, the same burr, after grinding the knife down a quarter inch? No, it's brand new metal. A brand new burr.

Someone said you could, basically, steel the burr to stand straight up. Fine, but that wire edge is going to be lost the first time you use the knife. It's easy to get rid of a burr. But just tearing off the burr will not leave you will a sharp, refined edge.

When, say, a coarse stone creates a burr that bends over to the opposite side. And you then switch your stone to that side and run the coarse stone, edge leading, that burr is going to be gone fast. You will, however, create a new burr on the opposite side.

 

[BluntCut MetalWorks]

Burrs are extremely weak, wire edges that are easy to remove. Many people just run their edge through cork or felt to remove them. The problem most people face is recreating a new burr while removing the old burr.

Imagine continually sharpening a blade with a coarse stone. You can keep going until the blade is worn out. And you say, "I just couldn't get rid of that burr; it just kept flipping from side to side." Actually, it's not the same burr. You got rid of burr after burr, but kept recreating a new burr. Do you really think it's the same metal, the same burr, after grinding the knife down a quarter inch? No, it's brand new metal. A brand new burr.

Someone said you could, basically, steel the burr to stand straight up. Fine, but that wire edge is going to be lost the first time you use the knife. It's easy to get rid of a burr. But just tearing off the burr will not leave you will a sharp, refined edge.

When, say, a coarse stone creates a burr that bends over to the opposite side. And you then switch your stone to that side and run the coarse stone, edge leading, that burr is going to be gone fast. You will, however, create a new burr on the opposite side.

I respectfully disagree with your new burr & wire-edge created as old burr/wire-edge removed. Here is my video I made a while back, which shown NO new burr nor wire-edge (ok, or possibly too small to observe and has negative performance).
http://www.youtube.com/watch?v=l2ynSDYEUYI

 

[Twindog]

Your video shows you folding the burr over at an extreme angle using a wooden dowl. Then you scrap the folded burr over a coarse stone with an edge-leading stroke. In the video, you seem to say that the burr then somehow flips to the other side, even though the burr is bent between the stone and the edge. When you sandwich a burr between the stone and the edge, the coarse stone is going to grind that wire edge off easily. I'm saying that you cut that first burr off, but recreated a new burr on the other side. It's an illusion that the burr flips.

 

[BluntCut MetalWorks]

I am confused now, not sure about terminology or we actually agree . In my video, once the folded burr got removed by edge-leading, the test cutting test shown that NO new burr get created. Similarly for the wire-edge. Note: I used edge-leading the whole time, so burr/wire-edge re-creation is minimal or too small to matter.

 

[Twindog]

I am confused now, not sure about terminology or we actually agree . In my video, once the folded burr got removed by edge-leading, the test cutting test shown that NO new burr get created. Similarly for the wire-edge. Note: I used edge-leading the whole time, so burr/wire-edge re-creation is minimal or too small to matter.

Sorry if I misunderstood you. So how do you not create a new burr if you are running the apex over a coarse stone? Did you lighten up on the pressure?

 

[BluntCut MetalWorks]

Sorry if I misunderstood you. So how do you not create a new burr if you are running the apex over a coarse stone? Did you lighten up on the pressure?

I probably did lowered the pressure a little bit however my low pressure would consider high for some... Here is my conjecture I posted last year http://www.bladeforums.com/forums/s...metry-cross-sectional?p=11390828#post11390828 = my hand-waving physics about burr-formation, which is may or may not convincing. I mostly rely on newsprint/phonebook/dry-shave tests to gauge the state of the apex whether it's burr/wire/rounded or free of burr/wire/rounding. One can easily test this conjecture by create an edge for plastic/wood/rubber knives. Edge-trailing = burr happy. Edge-leading = hardly burr.

OP - micro beveling technique worked for you probably (yes, I use this word often) because more metal below the apex provides additional stiffness to lessen the apex bend/roll. A large percentage of Sharpmaker users are use exactly this technique to touch-up their blades. So, sure it works if doing it right. I am a freehander, so only micro-bevel when I need to cut tough materials or situation call for edge toughness. Hence give up some slicing ability to gain additional strength.

 

[Obsessed with Edges]

'Flipping' a burr isn't an illusion. It's very easy to see this when flipping a REAL BIG burr on very ductile steel; a burr that's big enough to hold and see on your fingertip, after it breaks off. OR even in some cases, big, thin & ductile enough to actually fold or bend it with a thumbnail or fingertip. I bring this up, because when I first started sharpening to a degree that produced my first noticeable burr, I did just that. I had been using a guided system to sharpen a cheap stainless kitchen knife, and without even realizing what was happening, I noticed a BIG sliver of steel break off the edge when I wiped down the blade. I was literally able to hold and examine it on my fingertip. The guided hone had allowed it to cling to the edge far, far longer than would ordinarily be seen on a freehanded edge, because the precise angle control never bent it far enough break it off. Just kept grinding it wider and wider and thinner (with rather fine hones, at that point), so it was barely more than gold leaf thin by the time I rubbed the blade off with a tissue, and probably a millimeter wide (that's about half the width of a standard round toothpick).

I completely agree that some new burr can & will be created, in flipping an existing burr with an abrasive hone. It's harder to distinguish or see if the existing burr and the newly-created burr are both extremely small. But it's not entirely what's happening; sometimes (and I'd even say more often than not), there's at least some burr that actually gets 'flipped'.


David

 

[HeavyHanded]

Burrs are extremely weak, wire edges that are easy to remove. Many people just run their edge through cork or felt to remove them. The problem most people face is recreating a new burr while removing the old burr.

Imagine continually sharpening a blade with a coarse stone. You can keep going until the blade is worn out. And you say, "I just couldn't get rid of that burr; it just kept flipping from side to side." Actually, it's not the same burr. You got rid of burr after burr, but kept recreating a new burr. Do you really think it's the same metal, the same burr, after grinding the knife down a quarter inch? No, it's brand new metal. A brand new burr.

Someone said you could, basically, steel the burr to stand straight up. Fine, but that wire edge is going to be lost the first time you use the knife. It's easy to get rid of a burr. But just tearing off the burr will not leave you will a sharp, refined edge.

When, say, a coarse stone creates a burr that bends over to the opposite side. And you then switch your stone to that side and run the coarse stone, edge leading, that burr is going to be gone fast. You will, however, create a new burr on the opposite side.

Again, this is an oversimplification. There are two forces at work, abrasive and pressure. Pressure alone isn't going to remove a burr, and neither is abrasive potential, the two forces have to balance. Yes one could grind away indefinitely, and steel will continue to be removed, and some steel will fall away. Depending on the steel, that burr could get huge without letting loose. The entire thing just doesn't just fall off at the first indication of abrasive pressure, the attachment point is flexible. The burr has to be removed with intent. Imagine a large burr being ground from the opposite side. At what point in a stroke did the entire burr fall off to be replaced with a new, fresh one, of the same approximate dimensions? If you timed it perfectly you could cultivate a wire edge - that's not the same as tearing one off and replacing it. How exactly do you think an abrasive particle removes metal?


And not all burrs are extremely weak, only very small ones or ones that have been flipped repeatedly. Some burrs survive all manner of abuse. Furniture finishers use burnishing cards that have a deliberately formed burr, that thing isn't falling off on cork or felt.

 

[Twindog]

In my Wicked Edge, I can raise a burr on both sides of the blade using the coarse stone. After I've developed a burr on the right side of the blade, I can switch my coarse stone to that side and with a few strokes, the burr will show up on the other side.

But instead of using the coarse stone, I can switch to a fine-grit stone and use very light pressure, with the same number of strokes. The burr is gone.

So if the burr is just being flipped from one side to the other, how come I can completely cut the burr off with a fine stone, using light pressure, but it doesn't get cut off with the coarse stone using normal pressure?

The answer is that the burr gets cut off both times, but with very light pressure and a fine stone, it doesn't get recreated on the other side of the edge, as it does with the coarse stone.

 

[HeavyHanded]

In my Wicked Edge, I can raise a burr on both sides of the blade using the coarse stone. After I've developed a burr on the right side of the blade, I can switch my coarse stone to that side and with a few strokes, the burr will show up on the other side.

But instead of using the coarse stone, I can switch to a fine-grit stone and use very light pressure, with the same number of strokes. The burr is gone.

So if the burr is just being flipped from one side to the other, how come I can completely cut the burr off with a fine stone, using light pressure, but it doesn't get cut off with the coarse stone using normal pressure?

The answer is that the burr gets cut off both times, but with very light pressure and a fine stone, it doesn't get recreated on the other side of the edge, as it does with the coarse stone.

What's happening is that you're applying enough pressure to let the abrasive do its job, but not enough pressure to flip the burr. You could do the same thing with a coarse stone but likewise takes lighter pressure, also takes more frequent observation to avoid raising a new one and to eliminate it at different points along the edge. Try your example again, only use "normal" pressure with the fine stone. With a few passes the burr would flip, yet how could a fine hone possibly eliminate a coarse burr and create another largish one with only a couple of passes. I'm not disputing what you're seeing here, the burr can be ground off in place - that's the most reliable way to remove them, and that's exactly what I've been saying all along. But it doesn't happen haphazardly, or as an automatic response to pressure and abrasive action. If that were the case, you could use your coarse stone to raise a burr, switch to the other side, and using the same "normal" pressure that reliable eliminates and recreates it with a few strokes on the other side (or even more pressure), stop at half or quarter the number of strokes and the burr would be gone. Heck, why not bear down and only move the edge an inch or so on the stone?
Instead I think you'll find it stands up, aligns with the midpoint, and gets pushed over. Some of it will go, much will remain. Until you reduce pressure to the point where it stays put, but within the range needed for the abrasive to work efficiently, that burr will simply heave over.

I don't believe I have any more to contribute.