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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 8 months ago #6623

  • wickededge
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In my normal sharpening, I don't use much pressure when stropping. When I'm going for serious polish though, I use pressure at a lower angle at first and then lighten up as I get ready to finish.

The thing about lifting the base - I'm not necessarily trying to lift the base, but once my strops are well seasoned, they have enough grip that I have to try not to lift the base and have to lessen the pressure.
--Clay Allison
Last Edit: 1 year 8 months ago by wickededge.
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Re: A theory of how the WE diamond pastes work 1 year 8 months ago #6624

  • PhilipPasteur
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mark76 wrote:
wickededge wrote:
I removed the sample and cleaned it well, the completed 5 strokes per side with firm pressure using .75um CBN on cow leather.

I would never have intrepreted "Firm" to mean so much pressure that he was lifting the base on each stroke.
mark76 wrote:
I don't know whether you've read the posts on my blog regarding stropping, but in some experiments I did over 500 stropping movements per side. That is a lot :cheer: , and in order to see effect more quickly I used quite a bit of pressure.

I did and I commented on them previously.
mark76 wrote:
My pictures are not nearly as good as Clay's, but my conclusion was definitely that burnishing occurs, and that the WE pastes excel at doing this. That's why I started this threat ;) . You can read all of my posts on stropping here .

I think that sometimes we can start out doing an experiment with a preconception. The results will always tend to confirm that idea if we are not very careful. It is easy to just intrpret the results in a manner that confirms the theories we have going in.

I don't think you can see evidence of the kind of burnishing that Clay is talking about with 400X. This is why he wants to get time on an SEM to verify his theory.
mark76 wrote:
That is not to say that the common knowledge that you have to strop lightly is a myth. ...
Even with a WEPS, if you use a lot of pressure with a leather strop and don't adjust the angle, you will round the edge. So setting back the angle (with leather I do 1 or 2 degrees) is necessary if you use a little force.

I will look for the thread. I distintly remember Clay suggesting that just a few light strokes with leather would make a significant improvement at the edge. I think this may have been mentioned a few times actually. The suggestion was clearly that we did not need to do 500 strokes while lifting the base to get an improvement.

The point was not whether stropping with a light touch is a good idea, which I think in general that it is. The point was, if the majority of people do it this way, with any practical number of strokes, they would likely not see the effects that we are discussing.

Phil
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Last Edit: 1 year 8 months ago by PhilipPasteur.
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Re: A theory of how the WE diamond pastes work 1 year 8 months ago #6625

  • wickededge
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I circled some spots on the images so we'd have some things to compare. Here is the blade after the 50# diamond plates:

50-Grit-Detailed.jpg


and here it is after 5 strokes with the .75um strops:

75-CBN-after-50-Grit-Detailed.jpg


In the green circle and to some extent in the fuchsia ellipses, you can clearly see signs of abrasion from the .75um CBN. In the red and aqua circles, it looks like the metal has been dragged around a little bit. It has an almost liquid appearance as though it had flowed.

I don't have the background to speak to this, but I wonder, as Phil has voiced, if there is enough local pressure to move these delicate structures and deform them. I measured the little elongated structure in the red circle (after being stropped) to be 1.6um, which is very tiny. How many pounds per square inch would be needed to get something that small to flow? Even more to the point, can the leather grab surface molecules and shift them, like buttering bread? The next round of testing should be interesting. I'll try it with alcohol moistened strops with no abrasive other than the grain of the leather. Once the plain paste comes in, I'll try to duplicate the level of stiction I'm getting and test that way too, maybe on kangaroo.
--Clay Allison
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Re: A theory of how the WE diamond pastes work 1 year 8 months ago #6627

  • cbwx34
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I never thought I'd see "fuchsia" in a sharpening forum.... :)

Maybe someone who's a member of an engineering forum could post these pics and solicit some responses there?

I also had another thought along with trying plain leather would be to try balsa plain and/or loaded... see what that shows.
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Re: A theory of how the WE diamond pastes work 1 year 8 months ago #6628

  • Billabong
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cbwx34 wrote:
I never thought I'd see "fuchsia" in a sharpening forum.... :)

Me either, but it seems to work well.
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Re: A theory of how the WE diamond pastes work 1 year 8 months ago #6629

  • wickededge
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Okay, more photos raising more questions. First the 50# sample followed by the strops with no abrasives:

50-Grit-2.jpg


now plain cow leather, moistened with alcohol:

Plain-Leather-1---5-strokes.jpg


and then plain kangaroo leather, moistened with alcohol:

Plain-Roo-Leather-1---10-strokes.jpg


Next I'll post some pictures after using strops with some abrasives.
--Clay Allison
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