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

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.

Quote:

---

Originally Posted by mparker762

But he measures an edge from some coarse grit diamond (9 micron?) and it's 0.4 or something, and then later measures with 1 micron and it's 0.38 or so, and later with 0.5 micron chrome oxide and it's 0.37 or .36 or so.




Hmm, now I've got to go back to verhoeven's paper, because I distinctly remember them topping out at 0.34-0.38 past about 9 micron diamond, depending on the hardness of the steel and irrespective of grit.

---

I have the document open here:

0.35 to 0.45 is what he measures on a commercial blade.

0.4 is what he measure on a razor honed by one mr Dauksch

1 to 1.5 is what he reports to have found after honing on a 1000 grit wheel with "lightest pressure and slowest of wheel speeds"

0.50 is what he reports of a 6000 grit water hone.

He also tried a 8000 grit stone, but found that stone to leave sligthly coarser scratch marks than the 6000 stone. He concludes: "The results indicate that an advertised finer grit in this 6000 to 8000 size range does not guarantee a finer abrasive action."

0.35 is what he reports after stropping on CrO (at the bottom of p.27)

EDIT: I see we were both vigorously reading :)
Bart.

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."

Ok what we do?
don't we go untill 30000k?
Japan hones may come at least to 40000k.
there is differences between 8000k and 30000k shapton.

Quote:

---

Originally Posted by Bart

0.35 is what he reports after stropping on CrO (at the bottom of p.27)

EDIT: I see we were both vigorously reading :)
Bart.

---

On page 27 you're in a tormek chapter. Different situation altogether.

Another interesting snippet about it not mattering what the low grit hones do:

page 23:

"The edge quality was independent of the size of the burs left from the original grinding with either 600 grit or 1000 grit wheels. The coarser original burs of the as-ground 600 grit blades and the finer burs of the as-ground 1000 grit blades were both replaced with similar edge geometries."

Quote:

---

Originally Posted by mparker762

On page 27 you're in a tormek chapter. Different situation altogether.

---

I don't care. I own such a machine. CrO on a piece of leather remains Cro on a piece of leather, whether that piece of leather rubs against the edge, or whether you rub the edge against the leather.

The bottom line remains that the edge width is smaller.
The bottom line also is, that at Chosera 5K level, I can't pass a decent HHT, while the exactly same hair pops at the mere touch with the Chosera 10K edge. And falls silently once that edge is stropped. A stropped 5K edge pops hairs if I pull them a bit.

Some call it a parlor trick, but it a hair that we are severing, right?
Or is it a hair that we are splitting?

Whether the difference in performance is due to edge width, or to decreased friction, I believe am going to read Charlie's post one last time, and go to bed...

:)

After over 5 hours here are some things I have learned...

Sharp is still sharp it has to cut hair or it ain't sharp enough...

"Too sharp" is a relative term...

Spazola / Charlie is smarter than all of us :)

My definition of "too sharp" is overhoned...

At least I was at work and getting paid to sit here and discuss this...

So far this has been a most interesting discussion Thank You all ....

Quote:

---

Originally Posted by mparker762

Another interesting snippet about it not mattering what the low grit hones do:

page 23:

"The edge quality was independent of the size of the burs left from the original grinding with either 600 grit or 1000 grit wheels. The coarser original burs of the as-ground 600 grit blades and the finer burs of the as-ground 1000 grit blades were both replaced with similar edge geometries."

---

You see this man says what he sees.
he is talking about bar's on 600 or 1k level. that is all correct
after 8 k basically we don't have bar's. it is just straight line edge. now we make that edge narrower until we get highest grit stone we have used.