Confirming the removal of burr

S

Securis

Joined
Jan 9, 2013
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OK, i ask this because lately, i've been using the light reflection off the edge method to check for a burr/flat spot. I'd get it to the point where i won't see the wire. Does this mean i'm 100% burr free? Or is it just possible that i aligned the burr straight up 90 deg (if that's even possible)

Are there any other methods, short of getting a microscope, to confirm the presence or absence of a burr.
 
You can grind hard w/ pads of the fingers across the edge - spine outward. One side and the other. If you feel any difference the edge has a burr. Combined with overhead light visual check this is 90% or better certainty.

The human eye can see a candle flame at about 2 miles, and fingertips are sensitive enough to detect (according to researchers) differences on a nanometer scale. If there's a burr you'll detect it pretty much every time. Anything smaller is probably a non-issue.

The gold standard for me is to very lightly drag the edge at 90° along a piece of wood or plastic and check to see if anything has stood up, but I seldom resort to that anymore.
 
I can usually tell by feel or how cleanly a blade cuts through phonebook paper. I also use a loupe and a bright light to closely inspect the edge.

If there is any catch or rougher feel when cutting the paper, it is easy to spot the reason using strong magnification. I don't use a microscope. It's a Carson brand DV-30 document-inspection loupe I got at an office supply store for about $8 or so. There are much better tools, but that's what I have so I make do.
 
Slice SLOWLY, from heel to tip, through light paper (phonebook page, newsprint, magazine/catalog page, etc). If it slices cleanly without catching or slipping, along the full length of the edge, then you've likely done a good job fully apexing and cleaning up the burr. To check for sure, after the first slicing test in paper, then make a light cut into something like wood, or through a stack of paper, or cardboard; then make the same slow slicing cut in the light paper, and see if anything's different. If the edge is fully apexed and completely clean of burrs, then it should still slice the paper without snagging (burrs) or slipping (burr completely rolled over, or rounded/dull apex). Cutting into wood or stacked paper, or cardboard, is usually enough to fold/roll an existing burr on the edge; this is why it's useful to see how clean and durable a newly finished edge is, if it still slices cleanly in light paper afterwards.


David
 
Thanks for the responses guys.

When i started sharpening knives those years back, i've always used fingers to feel for a burr. But i believe there are things i can't feel that are there, i'm only a human with thick callouses on my fingers. But i can still pretty reliably test for bur just by feel.

Does it matter? I believe so. If it is a burr instead of an edge cutting, it's gonna last a cut or two, max.

Obsessed with Edges said:
Slice SLOWLY, from heel to tip, through light paper (phonebook page, newsprint, magazine/catalog page, etc). If it slices cleanly without catching or slipping, along the full length of the edge, then you've likely done a good job fully apexing and cleaning up the burr. To check for sure, after the first slicing test in paper, then make a light cut into something like wood, or through a stack of paper, or cardboard; then make the same slow slicing cut in the light paper, and see if anything's different. If the edge is fully apexed and completely clean of burrs, then it should still slice the paper without snagging (burrs) or slipping (burr completely rolled over, or rounded/dull apex). Cutting into wood or stacked paper, or cardboard, is usually enough to fold/roll an existing burr on the edge; this is why it's useful to see how clean and durable a newly finished edge is, if it still slices cleanly in light paper afterwards.


David
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that is actually an excellent idea. I've never thought about doing that. thanks!
 
Guess I should have expanded. By "cut stuff" I meant use the knife... not just one or two cuts.

If you can't tell in use... then what does it matter if you detect one under a microscope?

That's what I meant... if the only way you can detect a burr is by looking under a microscope... and can't tell when using the knife... then it's not important.

BTW, what OwE suggested is what I also do at a minimum after sharpening... cut some thin paper... then a couple of cuts thru cardboard... then chop up a piece of the cardboard, then check again on paper. It's a good test.
 
That's a very good question.

Are there any other methods, short of getting a microscope, to confirm the presence or absence of a burr.
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You mean YOU DON'T HAVE A MICROSCOPE yet :o :confused: :mad:
:p

Doesn't anybody screen these calls ? How'd this guy get in here ?

I hope you know I AM KIDDING.

But many many of us have microscopes. Sick huh ? Well as I always say "A person needs a hobby".

Some guy named Glasser (mental health expert) said "Find something to do just because THAT is what you do and do it as if your life and your sanity depend on it. Because they do".

I guess some of us have kind of over done it huh ?

The foily burs I get on A2 are so thin and flexible that they can not be felt but are easily seen. I hone with a jig on say a 8,000 or 15,000 water stone until they come off on the stone. Very OBVIOUS when this happens under a jeweler's visor. There is the little chips or string of wire edge laying there on the stone.

As far as getting the super fine bur coplanar on the blade and not being able to see it one thing I do is a super light palm strop with the blade parallel on my palm and the wave of skin will push the bur out of alignment without breaking it off and then I can see it under a strong light . . . again . . . usually I'm wearing and using my jeweler's visor. Overkill but harmless overkill that I enjoy.
 
cbwx34 said:
Guess I should have expanded. By "cut stuff" I meant use the knife... not just one or two cuts.

If you can't tell in use... then what does it matter if you detect one under a microscope?

That's what I meant... if the only way you can detect a burr is by looking under a microscope... and can't tell when using the knife... then it's not important.

BTW, what OwE suggested is what I also do at a minimum after sharpening... cut some thin paper... then a couple of cuts thru cardboard... then chop up a piece of the cardboard, then check again on paper. It's a good test.
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Yeah, i just tried it today. I ran the edge with decent pressure on a piece of wood (strop handle) lateral to the grain, and found no deformation, except on a brand new H1 blade (thing is so soft a burr will develop if you sneeze on it). Probably needs some work put through it first.

Wowbagger

"Forgive me father for i have sinned, i am without microscope!"

I gotta change that now don't I? shopping time! :D

I guess some of us have kind of over done it huh ?
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Let me tell you what's sad. No one here (where i am) really wants to talk to me about the things i read on here, not even knife people (ok, there are one or two). I'm so glad i have you guys to satiate my obsession.
 
Run your thumb down the edge in the direction of spine to edge. If its smooth check the other side. If its smooth too move on to the next grit or strop
 
Ummm, is it really, really, REALLY sharp? Bure is all gone!
 
Securis said:
Let me tell you what's sad. No one here (where i am) really wants to talk to me about the things i read on here, not even knife people (ok, there are one or two). I'm so glad i have you guys to satiate my obsession.
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So true, I share the same feeling. We're enabler here too, for you to go deeper into the rabbit hole ;)
 
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Chris "Anagarika";17033895 said:
So true, I share the same feeling. We're enabler here too, for you to go deeper into the rabbit hole ;)
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This is very common. Think how we knife makers feel. We spend a large portion of our time researching different steel compositions, grind angles, etc.... Nobody in normal public is anywhere near my level. Heck! Most knife guys aren't at my level! Sure they might be interested at first, but once anything is offered above their understanding, they to will lose interest. It's normal. People are not interested in things they don't understand, unless it was their idea to search for that particular piece of information in the first place. So naturally a forum would be the place to discuss things.
 
DavidHoback said:
This is very common. Think how we knife makers feel. We spend a large portion of our time researching different steel compositions, grind angles, etc.... Nobody in normal public is anywhere near my level. Heck! Most knife guys aren't at my level! Sure they might be interested at first, but once anything is offered above their understanding, they to will lose interest. It's normal. People are not interested in things they don't understand, unless it was their idea to search for that particular piece of information in the first place. So naturally a forum would be the place to discuss things.
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Yeah, i know what you mean. When i start getting technical about certain things, my boss says i bore the customer into a sale -,-

Another thing is, i go through all the steps, take every precaution, invest in the best materials to deliver the best result, and the customer doesn't notice the difference, or they don't care. Eh well, i know i'm doing the best i can, that's all that matters yea?
 
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