Thread: My razor is too sharp???? I like a duller edge??

Originally Posted by mparker762

The edge gets thinner and thinner until it gets to a certain point, then it just crumbles away, and continued honing just removes metal but the edge doesn't get any thinner. This seems to happen at around the 4k mark (obviously this is an approximation because different "grits" are different and act differently - the point is that this happens at a very coarse level, much lower than we would have thought).

.

This is True if you are talking about in curtain grit.
Example .
if you use 4 k and edge will get the level 4k can get . after that edge will not longer get sharper if you still using 4k
I agree
But we switch to 8 k and continue to hone edge will get thinner.
This is important understand.

i think what they made experiment was knifes etc.
how they sharpen knifes ? they will never get edge so thin which we get on straight razor.
that knifes edge will broke down after 1 potato cut right?
This is what they doing . they are getting edge on level of 4 k and stop in there . then they start to polishing . by polishing they get a little more sharpness that is it.
i check edge after 4k and 8k and after coticule ,escher.
as i go up edge gets thinner and cuts better .

One thing you have to be careful of with verhoeven's paper is making sure he's doing what we're doing. He does a lot of stuff with tormek machines and various abrasives, and somewhat less with flat hones and leather strops, and the two results are different because of the speed of the tormek machine and the additional angles involved (the razor can't lie flat on the wheel).


Here's two spots where verhoeven talks about this in a relevant context:

Page 23:

"Japanese waterstones in the 6000 to 8000 grit range produced an excellent edge on
these HRC = 60 stainless steel blades with as-ground 2β edge angles of around 40o. The
waterstones produced fairly smooth and quite straight edges as viewed face-on. The
remnant bur width was quite small, on the order of 0.5 microns"


page 24:

"Stropping of the waterstone sharpened blades on a leather strop loaded with chrome oxide compound produced a significant change in the edge geometry of the blades. The abrasive grooves from the waterstone sharpening were smoothed out significantly. The edge bur width was not reduced significantly below the 0.5 micron level of the waterstone ground blades, but it was perhaps a bit more uniform along the edge."


(reading furiously)

Continued:

from bottom of pg 9 - figure 12:

This shows a photo of a 1000 grit edge, taken at 3000x, showing the edge thickness is 1 micron.

He later references this in his flat hone and flatbed strop chapter as being his control blades for that chapter - he takes these and hones them on a variety of hones.

So at 1000 grit the edges are 1 micron thick. At 6000 grit they are at 0.5 micron thick. And at 8000x they are 0.5 micron thick. And at 0.5 micron chrome oxide they are also 0.5 microns thick.

The 0.38 number I was tossing around earlier appears to be the minimum thickness (the edge thickness varies at different places along the edge). But the minimum thickness appeared to be pretty constant. The maximum thicknes varies depending on burrs and such.

Another interesting snippet (pg 11):

"The 600 and 200 grit wheels produced surfaces that were difficult to tell apart. In both cases the face abrasion marks were significantly larger and the edge burrs significantly wider and more convoluted than found with the 1000 grit wheels. In addition, the face view of the edges were significantly rougher and less straight than on the 1000 grit wheels. Nevertheless, the edges produced by the 600 and 200 girt wheels are quite thin, with a burr width on the order of 2 to 3 μm on the 600 wheels and 2 to 4 μm on the 200 wheels. And, from a practical point of view, the edges are quite sharp, being able to cut arm hair as well as the 1000 grit edges. Neither cut hair as easily, however, as a razor blade. This later fact is probably due in large part to the much smaller edge angle of the razor blades, 2β of 17o versus 40o."