Big burr: how much material is lost?

CrimsonTideShooter

CrimsonTideShooter

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Oct 23, 2010
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So I'm sharpening my large Sebenza on my Chosera water stones, and I have a lapse in concentration and I end up forming a WAY bigger burr than I had intended on the 600 grit stone.

How much material are you losing each time you form a big(ish) burr? I'm not talking a huge highly visible burr, just large enough that you can clearly feel that it's there.
 
more than necessary :D

seriously i had to reprofile badly damaged edges a couple of times, with chips/rolls/whatever of several mm. during this process i often had very large burrs the kind you can see, touch and fold by hand. my undestanding is that the size of thing wil be no more than the height of blade you've lost. so imho don't worry too much about wearing out your sebenza ... it takes a lot of time to visibly wear a blade on a 600 grit stone even a chocera.
 
This is what really convinced me to use a good magnifier to frequently inspect the edge as I work. I used to go WAY past the apex, making BIG burrs. The first time I noticed this, it momentarily startled me, as I thought something was seriously wrong with the steel. I noticed a big sliver of steel break off into the paper towel I used to wipe the blade, and it took a moment for me to figure out it was just a HUGE wire edge breaking off. I was encouraged by the fact that I'd reached the apex (previously a problem for me), but had to really 'dial it back', in terms of how aggressive I went about getting there.

I've since gotten better at feeling the apex 'bite' the hone, when I reach that point. All the easier to feel that, if very light pressure is used, the closer you get to the apex. That's my cue to STOP and take a close look, to see where it's at.
 
Obsessed with Edges said:
This is what really convinced me to use a good magnifier to frequently inspect the edge as I work. I used to go WAY past the apex, making BIG burrs. The first time I noticed this, it momentarily startled me, as I thought something was seriously wrong with the steel. I noticed a big sliver of steel break off into the paper towel I used to wipe the blade, and it took a moment for me to figure out it was just a HUGE wire edge breaking off. I was encouraged by the fact that I'd reached the apex (previously a problem for me), but had to really 'dial it back', in terms of how aggressive I went about getting there.

I've since gotten better at feeling the apex 'bite' the hone, when I reach that point. All the easier to feel that, if very light pressure is used, the closer you get to the apex. That's my cue to STOP and take a close look, to see where it's at.
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I am very well versed in sharpening, and I normally know exactly when to stop. Like I said I had a momentary lapse in concentration. (I was making a YouTube video)


So, is the amount of material lost minimal?
 
CrimsonTideShooter said:
I am very well versed in sharpening, and I normally know exactly when to stop. Like I said I had a momentary lapse in concentration. (I was making a YouTube video)


So, is the amount of material lost minimal?
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I know you know what you're doing. Didn't intend to say or imply otherwise, in any way. I was just relating my own similar experience, and what I learned from it.

As for the material lost, I don't think it's that significant. Once the burr initially forms, the excess beyond that is very, very thin, in spite of it's seemingly large size. I wouldn't worry about it. The biggest pain I see, from overdoing it, is just removing the burr/wire, if the steel is very ductile. It implies more work, that otherwise wouldn't have been necessary. It's annoying, as you've related, but not a big deal. Especially since you recognized it right away. If one were doing this every time he sharpened a blade, that'd shorten it's lifespan considerably, over the longer run.
 
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Yes, very minimal.

Even during heavy re-profile with something as coarse as 120 grit it would take a conscious effort to get 1mm or more of material removed.
 
knifenut1013 said:
Yes, very minimal.

Even during heavy re-profile with something as coarse as 120 grit it would take a conscious effort to get 1mm or more of material removed.
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Ok good! I have found myself being very neurotic about "blade loss" when sharpening here lately. I have actually never known how a burr equates to material loss. Thanks for the education. :)

So you're saying it would take an extremely large ungodly absurd burr to even begin to recognize any loss in material?


Obsessed with Edges said:
I know you know what you're doing. Didn't intend to say or imply otherwise, in any way. I was just relating my own similar experience, and what I learned from it.

As for the material lost, I don't think it's that significant. Once the burr initially forms, the excess beyond that is very, very thin, in spite of it's seemingly large size. I wouldn't worry about it. The biggest pain I see, from overdoing it, is just removing the burr/wire, if the steel is very ductile. It implies more work, that otherwise wouldn't have been necessary. It's annoying, as you've related, but not a big deal. Especially since you recognized it right away. If one were doing this every time he sharpened a blade, that'd shorten it's lifespan considerably, over the longer run.
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Thanks man. Sorry if I sounded defensive, I didn't mean it that way at all. :)
 
A burr is a plastic flow of metal, its metal from the top of the bevel dragged to the apex of the bevel so technically the burr relates less to overall metal removal than it would seem. You remove more thickness than height when sharpening.
 
knifenut1013 said:
A burr is a plastic flow of metal, its metal from the top of the bevel dragged to the apex of the bevel so technically the burr relates less to overall metal removal than it would seem. You remove more thickness than height when sharpening.
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Ahhh ok! I always had it in my head that if your burr was X mill thick then that meant that you lost a proportionate amount of material.
 
A burrs size is mainly controlled by the pressure you are grinding with, you can see this yourself by grinding with varying degrees of pressure. With that in mind you should be able to make a edge burr free or very close with ANY grit/stone you use.
 
How much metal does a big burr waste?

Far too much, in my opinion. I like to raise a very tiny burr with coarse stones, but no burr at all past 320 grit.
 
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