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Stropping Discussions

TOPIC: A theory of how the WE diamond pastes work

Re: A theory of how the WE diamond pastes work 1 year 5 months ago #6596

  • mark76
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Would be really cool, Clay, if you could compare the burnishing (and abrasion) caused by the .75 CBN (which seems huge) to that caused by plain strops and by strops loaded with a WE paste.
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Re: A theory of how the WE diamond pastes work 1 year 5 months ago #6597

  • wickededge
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mark76 wrote:
Would be really cool, Clay, if you could compare the burnishing (and abrasion) caused by the .75 CBN (which seems huge) to that caused by plain strops and by strops loaded with a WE paste.

Hopefully I can do that today. I'm testing some arms from our machine shop and have to give feedback, so that will have to come first...
--Clay Allison
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Re: A theory of how the WE diamond pastes work 1 year 5 months ago #6598

  • cbwx34
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So, does this mean that when stropping and the edge seems to "dull" a bit, we're not necessarily "rounding" the edge, but rather pushing metal up on top of it?
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Re: A theory of how the WE diamond pastes work 1 year 5 months ago #6599

  • wickededge
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cbwx34 wrote:
So, does this mean that when stropping and the edge seems to "dull" a bit, we're not necessarily "rounding" the edge, but rather pushing metal up on top of it?

That is a really good question! It's conceivable that we are pushing metal up behind the edge, but I'm not sure how much we're really talking about. I'd like to do some good cross section studies and find out.
--Clay Allison
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Re: A theory of how the WE diamond pastes work 1 year 5 months ago #6605

  • PhilipPasteur
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Hey Clay,

I don't claim to be an expert, but everytime this subject comes up I go out and do more research on burnishing. In every case that I have come across burnishing is done with a harder material on a softer material. The idea is that you have to exceed the yeild strength of the softer material to get it to flow. There are some among us, even in the absence of hard evidence (not talking you Clay) that have accepted without question that leather can burnish steel. Clay, you have a theory, and you are out to find evidence to support that. This is entirely different.

I still have a hard time understanding how leather rubbed against hardened steel can exceed the yeild strength of the steel and make it flow, local pressures and stiction notwithstanding.
I did come accross an article today that stated, and I paraphrase, that in grinding (really what we do whe we sharpen) there will usually be some small level of burnishing because of the orientation of the abrasives and the fact that they are not all as sharp as the rest. These duller abrasives are being dragged accross the subject material and instead of cutting, they burnish. This effect can be considered to be minimal in the entire process of abrading the subject material. I can more easily see this as being the cause of what you are seeing at 2500X.

Keep in mind, I started my education...a long, long time ago, with a degree in mechanical engineering... the material science part of this just (from what I remember) isn't making sense (yet). This is why I am looking for different explanations.

I noticed in your first pic of the edge at 50 grit that there are some places where the metal looks like it has been burnished in small areas as evidenced by the smoothing of some areas. I am going to see if I can copy the pics and circle the areas... I am not a computer graphics wiz...and the forum does not let me copy the pics.

In the second picture it almost looks like some of the weakened areas have broken off and been pressed over some areas of the scratches. I would be interested to see if you continued to strop a bit more...whether those bits would just be swept away. In any case those areas are a small fraction of the surface... how important can they be to the overall finish, whether the results of burnishing, flaking, or something else...?? Still real curious about all of this, but not yet a convert...
:)

Curtis, I will be very interested to see what Clay comes up with if he can look at cross sections of the edge of the edge. As above, I will be extremely surprised if we are moving any metal, let alone enough to change the edge of the edge. But then, I can't imagine how a knife, or razor, gets apparently sharper when we use strops, if we are truly "rounding" the edge of the edge. If the cross section views are doable, this would be a great thing to look at as well. It would also be interesting to do some of those edge on shots, before and after stropping. Does the edge really get "rounded" making it thicker?? Or maybe are we just convexing a microbevel and actually leaving the edge thinner, but still a V even if only at the true microscopic level.

Phil
Phil

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I miss you Buddy!
Last Edit: 1 year 5 months ago by PhilipPasteur.
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Re: A theory of how the WE diamond pastes work 1 year 5 months ago #6606

  • cbwx34
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PhilipPasteur wrote:
I noticed in your first pic of the edge at 50 grit that there are some places where the metal looks like it has been burnished in small areas as evidenced by the smoothing of some areas. I am going to see if I can copy the pics and circle the areas... I am not a computer graphics wiz...and the forum does not let me copy the pics.

Here's the links to the 50g pictures...

wickededgeusa.com/media/kunena/attachments/52/50-Grit.jpg

wickededgeusa.com/media/kunena/attachmen...BN-after-50-Grit.jpg
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