Are you guys this nuts, or is it me? Angles and burrs
- This topic has 19 replies, 6 voices, and was last updated 04/04/2019 at 3:32 am by
.
-
Phillyjudge – My take on the differences between strops and DLF:
I use the example of a wire brush wheel to explain how stropping works. If you’ve ever used one, you would have seen that the wires don’t really produce the scratches you see with abrasives. Instead, it “burnishes” the surface, smearing high points down into a roughly polished surface in what amounts to a form of “cold flow.” Stropping seems to have a similar effect, as the abrasive particles are attached to a substrate which is relatively compliant. Rather than digging long trenches, the particles fold backwards and burnish the surface of the bevels. This ability to push the surface metal around is seen in a number of Scanning Electron Microscopy (SEM) images, where the steel at the apex of the edge is actually stretched up into a sharper, more exaggerated form. DLF can only remove material, but strops can actually move it, so while both can produce a mirror-like polish on the bevels, strops can enhance the sharpness.
This is not to say that DLF cannot enhance sharpness, but it does it by removing defects at the apex, thereby refining the edge. For this to happen, however, requires more than just producing a mirror polish. There would have to be a concentrated effort to remove edge defects at every step in the grit progression. Failure at any step to fully reduce edge defects to a minimum would make it quite difficult, requiring much more than a reasonable effort at every following step. This is why some of us have reported stropping for hundreds of strokes at each grit to achieve their goal.
This is my theory, and I’m sticking to it. ;- }
4 users thanked author for this post.
DLF will refine the edge to the extent that it can remove damage left by previous, coarser grits. Generally, the apex damage left by any grit will be deeper than the depth of the scratches it leaves on the surface of the bevels. This means that removing those scratches will not necessarily remove the apex damage left by the same grit.
To make this more apparent, after you’ve erased previous-grit scratches, crank up the magnification of your USB ‘scope and look at the apex directly from the side, rather than from the vertical or perpendicular to the bevels. You’ll see a ragged edge, much rougher than you’d expect.
The “ragged edge” I refer to here isn’t necessarily an undesirable thing. It constitutes a “toothy” profile which actually can enhance it’s performance, depending on what you’re cutting.
To expand for my previous post about strops vs DLF, I’d like to add the following. If it wasn’t quite clear, I believe that the “burnishing” action of stropping can actually move the steel around and can raise the apex to a finer, higher edge. It’s kinda like a 14-year old kid greasing his mowhawk haircut and brushing it up to a thin, vertical edge. Apologies to those of you who might have a greasy-mowhawked 14-year old kid. No insult intended.
- You must be logged in to reply to this topic.