Burr Free Sharpening Technique

[jasonstone20]

Not forming a burr while sharpening is a sharpening technique favored by a few people, namely Cliff Stamp and Sal Glesser (also most straight razor honers) although they use different techniques.  I use both methods of sharpening, forming a burr or not, but when I ask people if they use burr-free sharpening, the answer is almost always the same:  I can't get it to work for me.  The people asked are usually experienced in sharpening, so this puzzles me.  It took me about a week to get burr-free sharpening down.  I am wondering what people think about burr-free sharpening, if they use it, and how to get the technique to be learned easier and faster, as it can help with all forms of sharpening.

[grepper]

Could you please explain the process of burr free sharpening? How do you do it?

Also, how was/is it determined that no burr was formed?

[KnifeGrinders]

"burr-free sharpening" is a fancy term for edge-leading sharpening.
"most straight razor honers" change from edge-leading to edge-trailing on grits finer than #4000 because they know too well that the edge micro-chipping characteristic of edge-leading technique won't allow them to get a fine razor edge.

[grepper]

Edge leading produces burrs too. Seems like an odd term to describe it.

[SteveG]

Here are a couple of videos that explain it.

http://www.cliffstamp.com/knives/forum/read.php?7,6571

https://youtu.be/sXYI1yRBHiU

[Jan]

For me the term "burr-free sharpening" is a little bit misleading especially in discussion how it differs from "burr based sharpening". In my thinking more suitable term would be "burr minimization sharpening approach".
 
In my understanding the burr is formed as a result of plastic flow after each cutting operation, regardless if edge-leading or edge-trailing technique was used.
 
In machining the burr formed during edge-leading cutting direction is called entrance burr while the burr formed during edge-trailing is called exit burr. Exit burr height is usually greater than the entrance burr.
 
Jan

[jasonstone20]

For me the term "burr-free sharpening" is a little bit misleading especially in discussion how it differs from "burr based sharpening". In my thinking more suitable term would be "burr minimization sharpening approach".
 
In my understanding the burr is formed as a result of plastic flow after each cutting operation, regardless if edge-leading or edge-trailing technique was used.
 
In machining the burr formed during edge-leading cutting direction is called entrance burr while the burr formed during edge-trailing is called exit burr. Exit burr height is usually greater than the entrance burr.
 
Jan

Jan,
You are correct.  I think the term burr-free is used instead is because a burr is not purposely formed, or the goal of sharpening, and it's need for burr removal.  In the case a burr is formed, a micro-bevel is used to remove it, and since that is one of the normal final steps of burr-free sharpening (in the Cliff Stamp method), it isn't necessarily thought of as a separate step. Although for maximum edge sharpness, it is micro-beveling for micro-burr removal is used, then the knife is sharpened at the original angle again to remove the micro-bevel.

[grepper]

Mr. Jason uttered, "it is micro-beveling for micro-burr removal is used, then the knife is sharpened at the original angle again to remove the micro-bevel."

So, when the knife is sharpened again at the original angle, does that not create a burr that must be removed?

[Jan]

For me the term "burr-free sharpening" is a little bit misleading especially in discussion how it differs from "burr based sharpening". In my thinking more suitable term would be "burr minimization sharpening approach".
 
In my understanding burr is formed as a result of plastic flow after each cutting operation, regardless if edge-leading or edge-trailing technique was used.
 
In machining the burr formed during edge-leading cutting direction is called entrance burr while the burr formed during edge-trailing is called exit burr. Exit burr height is usually greater than the entrance burr.
 
Jan

Jan,
You are correct.  I think the term burr-free is used instead is because a burr is not purposely formed, or the goal of sharpening, and it's need for burr removal.  In the case a burr is formed, a micro-bevel is used to remove it, and since that is one of the normal final steps of burr-free sharpening (in the Cliff Stamp method), it isn't necessarily thought of as a separate step. Although for maximum edge sharpness, it is micro-beveling for micro-burr removal is used, then the knife is sharpened at the original angle again to remove the micro-bevel.

Jasonstone, thanks for your explanation!

My understanding how the burr is formed is shown in the attached sketch.

One might think that changing the direction of sharpening from edge-trailing to edge-leading will fully eliminate the burr, but strictly speaking it is not the case, because both burs were formed in a slightly different way. (I consider guided sharpening where the bevel angles are exactly the same for both sharpening directions. Results of free-hand sharpening, where the bevel angles are not exactly the same, may be different.)

   
 
Jan

[SteveG]

For me the term "burr-free sharpening" is a little bit misleading especially in discussion how it differs from "burr based sharpening". In my thinking more suitable term would be "burr minimization sharpening approach".
 
In my understanding burr is formed as a result of plastic flow after each cutting operation, regardless if edge-leading or edge-trailing technique was used.
 
In machining the burr formed during edge-leading cutting direction is called entrance burr while the burr formed during edge-trailing is called exit burr. Exit burr height is usually greater than the entrance burr.
 
Jan

Jan,
You are correct.  I think the term burr-free is used instead is because a burr is not purposely formed, or the goal of sharpening, and it's need for burr removal.  In the case a burr is formed, a micro-bevel is used to remove it, and since that is one of the normal final steps of burr-free sharpening (in the Cliff Stamp method), it isn't necessarily thought of as a separate step. Although for maximum edge sharpness, it is micro-beveling for micro-burr removal is used, then the knife is sharpened at the original angle again to remove the micro-bevel.

Jasonstone, thanks for your explanation!

My understanding how the burr is formed is shown in the attached sketch.

One might think that changing the direction of sharpening from edge-trailing to edge-leading will fully eliminate the burr, but strictly speaking it is not the case, because both burs were formed in a slightly different way. (I consider guided sharpening where the bevel angles are exactly the same for both sharpening directions. Results of free-hand sharpening, where the bevel angles are not exactly the same, may be different.)


 
Jan

In my interpretation of what Cliff is saying, *optimal* sharpening stops the moment the edge is apexed, thus not allowing for burr formation.  I can't argue whether this is true or not, though I can say that I've tried it - unsuccessfully.  Cliff's argument for edge-leading vs edge-trailing is that edge-leading moves damaged metal away from the apex, instead of into it.  His arguments seem to me to be more from the standpoint of edge-retention than achievable sharpness, and from optimal rather than practical sharpening, though his methods seem to work for him - wished they worked like that for me.