Why are burrs so malleable?

[me2]

The behind the edge thickness is normally measured at the top of the edge bevel.  On most western style knives, the edge bevel is about 1/16" to 1/8" wide.  On my JKK knives it was about 1/32" wide.  Perhaps top of the edge thickness is a more descriptive name.

[Bud]

Thanks Mr. Me2. I just keep on learning. Don't know if you can tell from the picture but I've got more than a 1/32 with this knife. I suppose that's because its probably a thicker knife than yours. To me, Japanese sushi knives are supposed to be super sharp small little thin things. My knife is none of the above. But that's okay with me because it worked just great on some venison tenderloin last night.

Don't mean to bug you but I've seen others talking about this behind the edge before too. So what's the meaning of this? If it's thin or thick behind the edge what difference does it make? I suppose that if I sharpened this knife at a smaller angle that the behind the edge would increase because this knife gets gradually thicker going toward the spine.

[me2]

That gets potentially pretty deep. I'll start another thread.

[me2]

Link to new thread:

http://www.bessex.com/forum/showthread.php?tid=266

[me2]

Discussion of stone sharpening moved to Salutations to Stone Sharpeners thread. Burr removal applies, but we're not to that stage yet with respect to the discussion in this thread.

http://www.bessex.com/forum/showthread.p...217&page=6

[grepper]

Thanks for starting a new topic Mr. me2. It's so easy to post a reply that, while relevant to the conversation, takes the post in a different direction. I know I'm guilty of being sloppy in that regard myself.

[EOU]

Back to malleable burrs or "flimsy" as we like to say around here.  We're having a good day here. We started with one test and are going to end up with two posts out of it. We started preparing another knife for our edge rolling tests and in the process noticed that we had created another one of those super flimsy burrs during the grinding process. This is a knife made by one of the BESS board members, Charles Bowersox, a couple of years ago. It was just kind of a fun project for him and he got to take advantage of the laser in the shop in the process. The blade is 1095 spring steel and if you believe Mcmaster Carr where he got the material, its about HRC 50. We're still wondering under what circumstances this type of burr is formed. Maybe we have some clues here. Here's the knife:

   

The knife was originally sharpened at 15 degrees and we're doing all our edge rolling tests at 19 degrees so that's where we ground it. You can clearly see the grind transition in this wider field microscopic picture.

   

This is the burr that was formed after grinding:

   

We've been here before. You can chase that burr for days, back and forth, back and forth. This time we smarted up and after just a few pursuits back and forth went to the rubber base pad on a Sharp Pad. Came right off in long pieces after just a few swipes. Here it is:

   

So the question was now "what did we do to the edge?". Tested it and the edge was 140. We know that KG isn't impressed but we were happily surprised. 140 is even a little sharper than we're used to with much better knives. So was it the change in grind angle that created this burr or the softness of the steel, or both, or something else? Good fodder for future tests. Right now we have bigger fish to fry.

[grepper]

Aside from the steel, etc., I can think of two things; better equipment and you are getting more skillful at sharpening.

[KnifeGrinders]

"This time we smarted up and after just a few pursuits back and forth went to the rubber base pad"

Rubber is the explanation.
What really matters is that deburring is done on a substrate more compressible than what you honed on in the previous step. Felt would have worked the same well for example.
Here lies the difference between honing (hard) and stropping (pliant), and between thinning away the burr (honing) and deburring the apex (stropping).
For complete deburring we have to overreach the edge apex.