bahsettiğim açıklama şöyle ( son paragrafı özet olmuş):
bart Adlı Kullanıcıdan Alıntı:linguist Adlı Kullanıcıdan Alıntı:Do you think using one or more layers of tape increases the sharpness of the razor?The answer is yes. But the possible yield in extra sharpness that can be obtained from the use of tape depends on the type of hone.
If you look at highly magnified pictures of an edge (preferably made with a Scanning Electron Microscope, like those found in the often cited paper, by prof. John D. Verhoeven, "Experiments on Knife Sharpening"), you'll see that the very edge of an "edge" is actually a radius.
Picture taken from aforementioned paper. The document is available online, here:
http://www-archive.mse.iastate.edu/filea...ShExps.pdf
Obviously, that radius is not a clean curve, but it is the main parameter to define the "sharpness" of the edge. I prefer to use the term keenness, as sharpness can also be influenced by additional factors, such as jaggedness of the edge and its enclosed bevel angle.
In my way of thinking, "keenness" only refers to the actual with of the radius at the peak of the triangle that we call "edge".
To make the radius smaller is to make the edge keener. Excuse me for stating the obvious, but this does lead somewhere. :-)
While honing, we achieve this reduction of the radius, by removing material from both sides of the edge bevel. But why doesn't the radius become infinitesimally small then? The answer is that the tip of the triangle also bumps into the particles of the hone. At the kind of magnification shown in Verhoeven's picture, the surface of a hone resembles a road paved with cobble stones. While the particles remove material of the bevel sides (effectively reducing the radius), the tip collides with the most protruding particles (actually increasing the radius). As long as the edge is still reasonably blunt, it is strong to withstand the impact, but as it gains keenness, it becomes more fragile and is more affected by the forces of the impacting particles. Eventually, the entire process will reach a balance: the edge gains as much keenness at it looses. Keenness has maxed out. Further honing will only remove more steel.
It should be clear that the smallest possible radius depends on a few factors. On some of those factors, we have no influence: the nature of the hone (short of using another one of course, but that defeats the scope of the original question), the type and treatment of the steel. But on others we can make a change: exerted pressure, the kind of fluid on the hone, edge-leading vs edge-trailing motions, and perhaps a few other things.
One important factor, I have left unmentioned to this point is: bevel width.
On wide bevels, the pressure we exert on the razor spreads out over a larger surface area. At the same time, this reduces the efficiency of the abrasion, while it increases the material removal required to obtain a given reduction of the edge radius. Both work against us: more material needs to be removed with a slower abrasion. It is a quadratic function, meaning that at very narrow bevels the difference in keenness gain per honing stroke improves dramatically. But there's more!
While the abrasion at the bevel shows drastic changes between wide and narrow bevels, the detrimental forces on the tip during impact stays fairly constant.
As a result, wide bevels reach a different "maxed out" radius than narrow bevels, because their slower bevel abrasion per stroke reaches the point earlier where it cannot make up for the tip detriment per stroke.
The effect can be easily observed with almost any (fine) hone. Hone a razor until fully maxed out. (can be probed with the HHT, which reaches a particular level without further improvement, no matter how many additional honing strokes). Next, add 2 layers of tape (one works too, yet two gives a bit more clearance), and make very few additional honing strokes (please make them light, we're working on an extremely narrow secondary bevel now). The razor will show an almost immediate keenness boost. As the secondary bevel grows, the edge will reach a new peak, and later even starts to decrease if the secondary bevel is allowed to grow wider than a certain point.
What I'd tried to describe above is not at all that different from what can be observed during finishing on a pasted strop. Due to flex or cushioning of the pasted strop it achieves something closely related to the effect of tape, namely a concentration of the abrasion at a small rim of steel near the very tip of the bevel.
Kind regards,
Bart.
