Ways to test for a burr?

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KennyB

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So the other day I decided to put a microbevel on one of my edges. The thing is, with a bevel that small, I'm not sure if I'm getting rid of the burr entirely. It cuts things cleanly, feels smooth, I can't feel anything with my fingernail, but for some reason one side of my blade shaves hair easier than the other. I can't really tell if it's because the hair on one arm is different, or if I have a burr.

Is there any way to tell if I have a burr by cutting something? It doesn't really seem like there's one on there, but maybe I'm missing something.

Perhaps I just didn't grind the microbevel very evenly? That an a burr are the only thing I could think of.
 
I'd love to have access to a microscope for my knife sharpening experiments for this purpose. I'm going to watch this thread to see if anything interesting pops up.

JGON
 
First way would be looking under bright light, if you have good eye sight and have the edge within 10in of your eyes it will be easy to see any burr.

Second, stropping your finger nail. I strop the edge on my finger nail over the length of the blade to see if it scrapes. If the edge is burr free the edge will feel like glass, if it has a burr any burr at all the edge will scrape or feel bumpy.

Besides that not much else is reliable past the grinding steps.
 
knifenut1013 said:
First way would be looking under bright light, if you have good eye sight and have the edge within 10in of your eyes it will be easy to see any burr.

Second, stropping your finger nail. I strop the edge on my finger nail over the length of the blade to see if it scrapes. If the edge is burr free the edge will feel like glass, if it has a burr any burr at all the edge will scrape or feel bumpy.

Besides that not much else is reliable past the grinding steps.
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Both of these are what I do. The whole "feeling the burr" thing with your fingertips only works until the burr gets small enough, and then you can't tell the difference.
 
THG said:
Both of these are what I do. The whole "feeling the burr" thing with your fingertips only works until the burr gets small enough, and then you can't tell the difference.
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Yeah, I use the edges of my fingernails and they've been able to catch pretty small burrs up until now.

knifenut, do you use the back side of your finger nail and just run it down the bevel face perpendicular to the edge?
 
Here's a leather strop that has what is advertised as textured leather that will show a mark on it if there's a burr http://www.japaneseknifesharpeningstore.com/product-p/lhone1.htm I have one on order, but have not used it. You don't have to order the whole system if you want. You can simply order a replacement metal-backed leather piece and use it on a piece of wood. I ordered the whole system, and will hopefully receive it in a week or two. There is a review on the site from someone who says it really does show when a burr is present. Just something to think about if the techniques mentioned above don't work for you. Another thing you should consider purchasing is the rock hard felt, either the block or the flat pad used with the strop base shown in the link. Those can help remove pesky burrs from your edge.
 
Kenny, I use the top of my thumb nail and with a stropping motion at the edge angle make short strokes as I move down the length of the blade. So far there is not a grit level I can't detect a burr at with this method, even when stropping. I also have a feel for it so it might take you a bit before you can feel a 50k burr ;)

Medic, If your good at keeping a burr small with your final finishing steps I don't think the strop will show much. Leather strops in general will show scrapes or drag lines from burrs.
 
knifenut1013 said:
Kenny, I use the top of my thumb nail and with a stropping motion at the edge angle make short strokes as I move down the length of the blade. So far there is not a grit level I can't detect a burr at with this method, even when stropping. I also have a feel for it so it might take you a bit before you can feel a 50k burr ;)

Medic, If your good at keeping a burr small with your final finishing steps I don't think the strop will show much. Leather strops in general will show scrapes or drag lines from burrs.
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Yeah, I think I may have got the hang of it. I went and raised a bit of a burr just to give it a feel, but I had to wait until there was enough of a burr to feel with my normal method. I could only barely feel when there was a burr, but I think I get the feeling you mean. Kind of feels like it's raking the surface. My thumbnails aren't really that smooth though, so even some of my really sharp knives I know don't have burrs don't feel totally smooth. :/

Oh well, I went back and sharpened using some alternating strokes. 6 per side, 3 per side, then 1 stroke each side until it seemed good. I'm just hoping there's no wire edge left on it. I don't have good vision, but there doesn't seem to be anything on there judging by my 30X loupe; just a really big chip that I haven't gotten all the way out yet--that's the whole reason I'm putting the microbevel on. Case CV + 30* inclusive bevel + Leather = Bad

So far so good, all things seem pretty much equal and it's as sharp as I usually get. I can't help but feel like maybe I've still got a burr on there I'm noticing though. :/

This is pretty much the smallest microbevel I've ever put on, and I usually check for burr by running the edge of my fingernail up the bevel to see if it catches on something, but the microbevel is really hard to test like that because it's so tiny.

My camera barely picks it up
microbevel.jpg

Closeup: http://img683.imageshack.us/img683/4414/microbevel2.jpg
 
To me that looks like A) a fairly consistent burr along the edge or B) a consistent burr but the edge behind it appears to have dents, deformations, and the apex is just shy of meeting.


Tilt the edge down 10 degrees and take another pic.
 
knifenut1013 said:
To me that looks like A) a fairly consistent burr along the edge or B) a consistent burr but the edge behind it appears to have dents, deformations, and the apex is just shy of meeting.


Tilt the edge down 10 degrees and take another pic.
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Oh no, the shine in that picture is the microbevel--I really mean it when I say it's tiny. Here's kind of a better one, but my camera really can't zoom that well. This time I got the main bevel to shine and the microbevel is in focus. I marked where it transitions with blue, and I also underlined the chip I'm talking about in red. It was significantly bigger before I started, and I've still got a bit to remove it seems. I can't believe leather chipped it out that bad.

microbevel3.jpg
 
KennyB said:
So the other day I decided to put a microbevel on one of my edges. The thing is, with a bevel that small, I'm not sure if I'm getting rid of the burr entirely. It cuts things cleanly, feels smooth, I can't feel anything with my fingernail, but for some reason one side of my blade shaves hair easier than the other. I can't really tell if it's because the hair on one arm is different, or if I have a burr.

Is there any way to tell if I have a burr by cutting something? It doesn't really seem like there's one on there, but maybe I'm missing something.

Perhaps I just didn't grind the microbevel very evenly? That an a burr are the only thing I could think of.
Click to expand...

For what it's worth, I often see the same thing. Shaves hair from one side, but not the other. More often than not, in my case, it's usually an asymmetrical microbevel. In effect, the edge is skewed more to one side than the other.

The fingernail test works well for me, in finding burrs. I'll strop the edge on the nail, as knifenut described, and look for the scraped off material along the edge, for each side. I also hold the edge perpendicular to the nail (straight up/down), and slide/scrape in each direction. If the edge is uniform & symmetrical, and burr-free, I should be able to scrape material from my fingernail in each direction.
 
My guess is your using too much pressure on the micro causing excess deformation.
 
knifenut1013 said:
My guess is your using too much pressure on the micro causing excess deformation.
Click to expand...

I could see this, because whenever I try to get the microbevel going, the knife is at such an extreme angle that it feels very sticky on the stone. Takes a good bit of pressure to get it going.

I stayed up last night grinding it and testing burrs on my fingernails, but I'm not sure I'm getting the hang of it. The only ones I can feel are huge.

I wonder if I shouldn't just forget about the microbevel and just put on a more obtuse bevel. It would probably take care of that chip a lot quicker. Kind of liked the microbevel for speed of maintenance though.
 
Use the lightest of touch, nearly zero pressure, and you will notice huge improvements in burr reduction.
 
knifenut1013 said:
Use the lightest of touch, nearly zero pressure, and you will notice huge improvements in burr reduction.
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Well, what I mean is that when I started out through the stroke, the knife wouldn't move on the stone. So I had to kind of put a little more effort into the stroke then I usually do just to get it moving. Feels like I may have gouged the stone except that it felt smooth as it normally would after getting the bevel started.

I'll see what using extreme light pressure when getting started does later today. I think that I can manage to just use lighter pressure to get it going so I don't gouge the stone. I've still got that big chip to take out, so we'll see.
 
I test for burrs by stropping on the back of my head. The hair will catch and pull on any burr I've had. I used to use my arm, but the hair there is coarse and tangled. The hair on my head doesn't work right after a haircut.
 
That's probably a issue.

IMO that is far too coarse for a microbevel, do you have a ceramic rod?

In reference to post #10, I can see the burr in your pictures. Also that is not a chip..... wait, leather caused that ???
 
knifenut1013 said:
That's probably a issue.

IMO that is far too coarse for a microbevel, do you have a ceramic rod?

In reference to post #10, I can see the burr in your pictures. Also that is not a chip..... wait, leather caused that ???
Click to expand...

Hmm, how can you tell there's a burr? The only thing that seems off to me is that little strip of white at the edge, and I can't see that without the camera; even my 30x loupe doesn't show that.

And yeah, leather did that. Plus it was a lot bigger before that picture.

Also, the only thing I have finer than 1000 grit is my CrO strop.
 
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