Micro burrs: at what point is a burr a non-issue?

[Spey]

The only media I can produce functional sharp burred edges off of is ceramics. I know I am not mistaking them, and the edges cut well, pass a crossgrain newsprint test and in some cases whittle hair. I suspect the difference is off of other media it is a true grinding artifact and off the ceramics its got a healthy dose of burnishing added in which can slightly draw out the edge as it work hardens it.

A good test is to give the edge a moderate smack directly into a hardwood dowel or similar. The edge will throw back light where its been hit as this burrs folds up. I normally need a loupe to see them, so if you're able to see with the naked eye you probably are seeing a burr. A microbevel will show light back at a more obtuse angle, the burr shows at a more acute - edge down, you will have to tilt the blade more to see the microbevel, the burr presents as a halo just off the apex.

I don't get this off of other media, tho did used to get a similar issue when backhoning on waterstones. If too much force was used the edge will curl slightly and look almost like a burr, almost like a wire, almost like a clean edge depending on how far it curled.

Interrogate them thoroughly, but always trust your eyes.

HeavyHanded,

Most excellent comments!

The work hardening effect and burnishing are the two things I was thinking about related to ceramics (plastic deformation & re-deposition effects). As blade steel has evolved (harder base metals and carbides) the cutting vs. burnishing efficiency of our media of choice has to be reconsidered.

I also really liked your comments related to how the light reflects (based on convexity or concavity of the surface). Being cognisant of where the light is coming from and at what angle the reflection determines the shape of the reflecting face and how what we see can/should be interpreted.

Good stuff !

 

[Jamesh Bond]

Checked again. Martin's Description of a halo past the cutting edge is dead on.

If I had to bet, my money is on burr. Still just as confused at the behavior tho. Maybe the variable is in my perception of it.

Spey, to answer your question, the information regarding ceramics being burr-prone is all over the place. I first read it here years ago. I see it enough I honestly thought it was common knowledge.

Also, I'm not using a V or sharpmaker. As I said, Pro-file set, by hand.


Thx.

 

[Chris "Anagarika"]

I did quick experiment:

Took my old SRM 710 (8Cr13MoV) to Spyderco UF, checked the edge, there's a bit of burrs (felt with fingertips). Did a few of light edge leading pass, removed all burrs.
Followed by slightly higher angle (microbevelling?) very very lightly pass. It's sharp, slicing receipt paper without problem, but since I don't have my loupe with me, so I couldn't see the halo as described.
Having sliced several times into receipt paper, I could however, feel the burr 'pushed' to the other side. Right hand slice into paper held with left hand side, the apex naturally got 'pushed' to the opposite (non presentation side, i.e. lockbar side if frame lock). It continued slicing without problem though. Switching hand, slice with knife on left hand and paper on right, I could feel the 'burr' now pushed to the other side.

Took out my endgrain strop (with Dialux green) and did several pass stropping. It sliced better (quieter) and less 'burr' got pushed aside, try both hands, etc. Anything remaining, got stropped again, until slicing didn't result in perceptible 'burr' pushed aside.

Perhaps the question would be how strong and tenacious the burr is and how it fared in cutting, and how smooth it continues to cut. It is possible what I witnessed was rolling instead of burr (?). If the material being cut is hard (like smacking dowel example), I'd guess it would fold immediately.
It is also possible that the 'rounded' apex because of stropping is stronger, so the edge / apex doesn't roll.

 

[Spey]

... , in spite of my best efforts, I nearly ALWAYS end up with what appears to be microscopic burr on the length of my edges when I finish with ceramics. Yes, I know the tricks, and have tried everything to remove it. I can get it off if I really try, but at the cost of time, frustration, and edge precision.!

The strange burr I'm seeing only happens with the Spyderco Ceramics. It shows up from both sides.
Im assuming it to be a burr because I know ceramics are prone to producing them. And I know my technique could always be the cause.
I'm just weirded out that it doesn't exhibit any actual effects.

( "... appears to be microscopic burr on the length of my edges when I finish ...")
+
("It shows up from both sides.")
=
From everything I have read in this thread, you are saying it appears the same on both sides of the blade?
Burr unlikely on both sides of the edge, extending length of the edges.

Checked again. Martin's Description of a halo past the cutting edge is dead on.

If I had to bet, my money is on burr. Still just as confused at the behavior tho. Maybe the variable is in my perception of it.

Spey, to answer your question, the information regarding ceramics being burr-prone is all over the place. I first read it here years ago. I see it enough I honestly thought it was common knowledge.

Also, I'm not using a V or sharpmaker. As I said, Pro-file set, by hand.

Thx.

Sorry, I can not remember reading that you were hand sharpening with a Pro-file set of stones. What I related to regarding the effect on the edge still applies in my mind.

At this point, it seems to me the possibility exists that the wealth of "common knowledge" you have acquired related to burrs from ceramic stones may be a hinderance to the revelation of what you are actually seeing & experiencing.

OwE, pretty much nailed what I was thinking (unintentionally induced additional micro-bevel), also previously described by awestib.

I think getting some magnification on would really help you out on this. Jewelers loupes can be had pretty cheaply these days (I believe the quality of the glass and how you use the tool is more important than the power of the magnification).

I look forward to learning about your answers to this issue ;-)

 

[Gaston444]

All that aside, if you're not seeing any impediment to cutting, i.e., if the edge shaves from both sides (a turned burr only does this well from one side), and slices light paper cleanly and repeatedly with no snagging or slipping, I wouldn't worry too much about what you think you're seeing. It very likely IS just a microbevel, at that point, as burrs won't perform that consistently in such tests. The cosmetics of the edge will improve in time, with sharpening experience, and you'll start noticing you're not seeing that thin band of reflected light anymore, along the apex. That's the path I went down.

Any significant burrs that I've ever made that were visible by naked eye, were always an impediment to cutting, and cutting performance varied and/or degraded from one pass to the next with most of them, as they'll always move/turn with a few cuts in most anything beyond shaving tests. Really heavy, stiff burrs won't necessarily move so easily, but they'll reveal themselves in more obvious ways, by feel with the fingertips, or by obvious differences in cutting from each side of the apex, or just in poor cutting overall.


David

While it is generally true that burrs will cut phonebook paper in an inconsistent manner (phonebook paper being especially sensitive to this), this is mostly because burrs often happen early in the sharpening process where everything is rougher... However some burrs can develop late, and those can be highly refined and consistent, and at this point there is no way to judge from pure cutting performance in soft mediums that it is not there: I have found often that excellent slicing can be very misleading, including shaving which is the most misleading of all...

Another strangeness is that you can occasionally feel the burr nail grabbing from both sides to some extent: This I theorize is caused by a burr taking a "set" after flip-flopping on both sides, meaning the burr has a displaced base opposite to the lean, and that bent base can also slightly "grab" nail material opposite to the lean...

Nail grabbing is still the most sensitive non-optically aided method I know of, because it sheds whitish materials that greatly exaggerate what is going on, and this proportionately to the severity of the burr: This is very useful in determining which spots are worse, and in which direction they lean.

It is true that when the edge suddenly "runs" with carefree cleanless through phonebook paper, immediately after you identified a burr that you wanted removed, this CAN mean you successfully removed it. But it is not an absolute.

Also I heard there is always a tiny burr no matter what, but magnification images I have seen don't seem to support this...

Gaston

 

[Jamesh Bond]

( "... appears to be microscopic burr on the length of my edges when I finish ...")
+
("It shows up from both sides.")
=
From everything I have read in this thread, you are saying it appears the same on both sides of the blade?
Burr unlikely on both sides of the edge, extending length of the edges.




Sorry, I can not remember reading that you were hand sharpening with a Pro-file set of stones. What I related to regarding the effect on the edge still applies in my mind.

At this point, it seems to me the possibility exists that the wealth of "common knowledge" you have acquired related to burrs from ceramic stones may be a hinderance to the revelation of what you are actually seeing & experiencing.



I think getting some magnification on would really help you out on this. Jewelers loupes can be had pretty cheaply these days (I believe the quality of the glass and how you use the tool is more important than the power of the magnification).

I look forward to learning about your answers to this issue ;-)

Thx Spey.

The burr stands out like a halo, as Martin said. Visually, it looks like a textbook Wire Edge. Barely perceptible, but stands out from the apex.

Behaviorally, it acts like solid metal, showing no degradation.

If I had the foresight to sum up my entire confusion, I would have posted nothing more than the above to start with!

I honestly can't detail it out any more than that! Even though a lot of heavy hitters have responded with ideas, the mystery remains.

I haven't heard anything new, which is actually a good thing. It indicates I haven't missed anything huge knowledge wise. No complaints about that either! I definitely appreciate everyone's time and interest here! It's always good to be reminded, or hear something you thought you knew we'll in different words.

My best guess as to what I'm seeing has always been, and after reading these responses, still is:

* It is a tiny micro wire edge posessing exaggerated strength and visibility due to the burnishing effect of the ceramics.

The perceived lack of burr-like problems is most likely a result of it being so tiny it isn't having much effect. It looks bigger cuz it's shiny! *

That comes the closest to satisfying most factors. However, it doesn't explain everything, like how it is tiny and fragile yet hangs on without dulling at the same time. Or errors in my perception and judgment.

You nailed it on the head with your reference of too much knowledge skewing what I am seeing.

You're right. A new loupe would help. Or maybe hurt lol. When you consider that if I didn't see this anomaly, I wouldn't know about it, it makes ya wonder how significant it is.

First world "problems," OCD, and overthinking! Thank 'Murica for forums!

 

[Obsessed with Edges]

While it is generally true that burrs will cut phonebook paper in an inconsistent manner (phonebook paper being especially sensitive to this), this is mostly because burrs often happen early in the sharpening process where everything is rougher... However some burrs can develop late, and those can be highly refined and consistent, and at this point there is no way to judge from pure cutting performance in soft mediums that it is not there: I have found often that excellent slicing can be very misleading, including shaving which is the most misleading of all...

Another strangeness is that you can occasionally feel the burr nail grabbing from both sides to some extent: This I theorize is caused by a burr taking a "set" after flip-flopping on both sides, meaning the burr has a displaced base opposite to the lean, and that bent base can also slightly "grab" nail material opposite to the lean...

Nail grabbing is still the most sensitive non-optically aided method I know of, because it sheds whitish materials that greatly exaggerate what is going on, and this proportionately to the severity of the burr: This is very useful in determining which spots are worse, and in which direction they lean.

It is true that when the edge suddenly "runs" with carefree cleanless through phonebook paper, immediately after you identified a burr that you wanted removed, this CAN mean you successfully removed it. But it is not an absolute.

Also I heard there is always a tiny burr no matter what, but magnification images I have seen don't seem to support this...

Gaston

The inconsistent burr behavior I spoke of, in phonebook paper, is based on what I've seen at pretty refined finish, i.e., at polished or near-polished, around 2000-grit or a little higher (usually as far as I've taken the finish on any blade, as I've never felt the need to go further). At that stage, when cutting phonebook paper, I noticed a few snags in the first cut or two, then often one of two things happened: (1) either most of the burr then stripped away in the paper, after which cutting became more consistent and smoother, or (2) the burr folded completely and didn't strip away, after which cutting completely stalled. At that higher level of finish, the burrs I've left have never been strong or robust enough to cut consistently well for more than a few cuts, even in something as light as phonebook paper. They've always been too thin & weak to sustain it. As per the two different scenarios mentioned above, more ductile steels' burrs were very quick to fold without stripping/breaking off (420HC at mid-50s HRC, VG-10 below 59 HRC, for example), and harder steels' burrs generally would strip or break away pretty easily after the first couple or three cuts in paper, after which the cutting performance improved markedly. Such examples of that are well-hardened 1095 especially (Schrade USA), but also harder variants both 420HC (57-59 HRC) and VG-10 at 60 HRC or higher.

The burrs I've seen which were more robust, and sometimes able to cut fairly well (if NOT folded over), were much coarser; often following the first grinding stage (maybe 220-320). Certain steels, like ATS-34, can retain amazingly tough & strong burrs up through a higher finish, but they're still quite obvious, and exhibit classic burr behaviors (easily felt by fingertip, very asymmetric cutting behavior from side-to-side).

And in my experience, shaving performance of burrs has almost always been variable from side-to-side, as there's almost always a little bit of 'lean' of the burr to one side or the other, meaning it'll angle down into the base of the hair from one side (meaning it's much easier to pinch and cut hairs away at a low angle), and angles up & away from it from the other side (tends to run/slide up & over hair being laid down in front of it). When I see obvious asymmetry in shaving like that, I can almost always be sure there's a turned, fine burr at the edge, and usually a few passes over bare leather or denim will clean that up and get it shaving equally well from both sides.


David

 

[HeavyHanded]

Thx Spey.

The burr stands out like a halo, as Martin said. Visually, it looks like a textbook Wire Edge. Barely perceptible, but stands out from the apex.

Behaviorally, it acts like solid metal, showing no degradation.

If I had the foresight to sum up my entire confusion, I would have posted nothing more than the above to start with!

I honestly can't detail it out any more than that! Even though a lot of heavy hitters have responded with ideas, the mystery remains.

I haven't heard anything new, which is actually a good thing. It indicates I haven't missed anything huge knowledge wise. No complaints about that either! I definitely appreciate everyone's time and interest here! It's always good to be reminded, or hear something you thought you knew we'll in different words.

My best guess as to what I'm seeing has always been, and after reading these responses, still is:

* It is a tiny micro wire edge posessing exaggerated strength and visibility due to the burnishing effect of the ceramics.

The perceived lack of burr-like problems is most likely a result of it being so tiny it isn't having much effect. It looks bigger cuz it's shiny! *

That comes the closest to satisfying most factors. However, it doesn't explain everything, like how it is tiny and fragile yet hangs on without dulling at the same time. Or errors in my perception and judgment.

You nailed it on the head with your reference of too much knowledge skewing what I am seeing.

You're right. A new loupe would help. Or maybe hurt lol. When you consider that if I didn't see this anomaly, I wouldn't know about it, it makes ya wonder how significant it is.

First world "problems," OCD, and overthinking! Thank 'Murica for forums!

FWIW I almost never use any of my ceramics anymore, including my ceramic rod and Spyderco. Is not because they don't work, but they require more QC and futzing the burr than any of my other options, and end of day the edge isn't any better than other means. If you want a more refined edge without the ceramics get a polishing grade waterstone, diamond plate, hard strop.

 

[Obsessed with Edges]

FWIW I almost never use any of my ceramics anymore, including my ceramic rod and Spyderco. Is not because they don't work, but they require more QC and futzing the burr than any of my other options, and end of day the edge isn't any better than other means. If you want a more refined edge without the ceramics get a polishing grade waterstone, diamond plate, hard strop.

Ditto this^, for me. I sometimes fiddle around with ceramic hones, and that's usually with a V-crock type setup, if only to put some quick bite into a kitchen knife on the fly. Even then, I almost never use anything beyond the Medium Spyderco (brown) or equivalent from other sets. And given the same option today, I'd be just as quick to use one or the other of two oval diamond rods I have, for exactly the same reason. As in the above, if I'm looking for more refinement beyond that, I can do that more easily, and more effectively, by other means.

The biggest drawback to ceramics, in my view, is their tendency to produce burrs if technique isn't steady and very light. This is a small part of the reason I sometimes fiddle with them, as it's a pretty good gauge of a skilled touch on any hone. If one can control the burrs on a ceramic, either by minimizing them from the start, or doing a good job cleaning them up, they can be comfortable with their touch on anything else.


David

 

[Jamesh Bond]

Agreed guys. I'm happy with my simple method of DMT c/f and use it pretty much exclusively.

I keep the Profile set around because it's cool, and most definitely reveals flaws in technique.