Thread: Rockwell hardness and honing

Now, I'm a new guy here, so maybe I should keep my big mouth shut when it comes to honing razors... However, not knowing what I'm talking about never stopped me before..
I will just relay some thoughts as a career metal worker..
I don't think that hardness alone tells the tale of honing, or grinding ease or difficulty. Within the same alloy, I doubt if anyone could detect a difference in a couple of points on the Rockwell scale, and I would imagine that most fairly modern razors would be above 57 or 58 on the C scale.
Different alloys could be a different story however, and can make a world of difference in grinding, and I assume honing.
Before dies, and quite nice ones, started to appear from the Orient, for the same reasons as everything else comes from the Orient, many dies we built were made of D-2, or "High Carbon, High Chrome," and it is a bear to grind!! As much time dressing wheels as actual removal of material. I'd always prefer to design a die from O-1 over D-2! As an interesting aside, we also built more "life" into our dies than the low cost orientals, and i suppose that's because the product would be redesigned or improved before the life of the die came due... a sign of the times!
Anyway, my thought is that a different alloy could make more difference in honing difficulty, or time to achieve the result, that relative hardness of equal alloys..
I could very well be all wet.... I'm just adding an opinion... and food for thought.

P.S.
I've recently come to learn that there is a custom maker that will take a commission for a straight razor in D-2... That man has my utmost respect!

Originally Posted by BlacknTan

not knowing what I'm talking about never stopped me before..

+1 I resemble that remark. Kidding aside, I agree with your observation on the alloy and difficulty in machining, grinding or honing. When I was a young fellow I was a union ironworker and one job I worked on was erecting Clinker Coolers in cement plants. The wear plates that sifted the clinker were 304 stainless to resist the high abrasion of the red hot and highly abrasive material that was processed. The kilns we erected were mild steel but the scoops inside were of stainless to stir the cement as it worked it's way down the kiln from the precipitator to the cooler. Point being that stainless was used for the characteristic of abrasion resistance and as you noted, among stainless alloys some are more resistant to abrasion, therefore honing, than others.

Originally Posted by Disburden

Each number, if I am correct, is referring to the amount of laps that particular razor may need on the basic hone Grits Glenn Mentioned. For example my Henckles may need: 20 (1k), 20, (4K), 30 (8K), and then 10 (12K).

Exactly correct

Originally Posted by BlacknTan

Within the same alloy, I doubt if anyone could detect a difference in a couple of points on the Rockwell scale, and I would imagine that most fairly modern razors would be above 57 or 58 on the C scale.
Different alloys could be a different story however, and can make a world of difference in grinding, and I assume honing.

The circles I run in it is not hard to tell by use what RC range a blade it in. It's also not hard to guess what ally has chromium or vanadium in high or low ammounts. The difference between a 63 and 65 RC knife can be extreamly noticeable on the board as well as on the stones. I see the same results on razors. Yes many call us knife geeks (Especially the knife makers) but you see a patern after you play with enough kitchen knives. While I haven't played with nearly as many razors as I have high end kitchen knives, I'm working on it :P

So many factors come into play, I'm just pointing out a few of my observations over the past few years.

Originally Posted by BlacknTan

Now, I'm a new guy here, so maybe I should keep my big mouth shut when it comes to honing razors... many dies we built were made of D-2, or "High Carbon, High Chrome," and it is a bear to grind!! As much time dressing wheels as actual removal of material. I'd always prefer to design a die from O-1 over D-2!...
I've recently come to learn that there is a custom maker that will take a commission for a straight razor in D-2...

I had a little experience with metalworking/tool& die work in a prior career. I wish I had access to the equipment, I would LOVE to have/make a D-2 razor. It would be a bastard to work with, but worth the effort I'm sure...

Originally Posted by DwarvenChef

The circles I run in it is not hard to tell by use what RC range a blade it in. It's also not hard to guess what ally has chromium or vanadium in high or low ammounts. The difference between a 63 and 65 RC knife can be extreamly noticeable on the board as well as on the stones. I see the same results on razors. Yes many call us knife geeks (Especially the knife makers) but you see a patern after you play with enough kitchen knives. While I haven't played with nearly as many razors as I have high end kitchen knives, I'm working on it :P

So many factors come into play, I'm just pointing out a few of my observations over the past few years.

A good example of how sharpening things informs the sharpening of things.

Well one thing, just to add to the discussion: my understanding was that any hone (or paste) with which we intend to cut steel must be harder than steel. But only *part* of the stone will be composed of that hard abrasive particle - the rest is just "glue", e.g. the "garnets" in the coticule actually do the work. In coticules they are 25%-40% of the total content. I imagine the range is broadly similar in other natural stones as well. So I think some of the "hardness" of the hones that we feel has to do with the hardness of the "glue", which WILL affect various aspects of the honing process. But you *must* have the hard abrasive particles be harder than steel for it to be an effective hone.

Now, that said, I also wonder: I just recently got some Nanwias for the first time, and have been loving them - amazing combination of fast cutting and fine result. BUT what is interesting is how soft they are, especially compared to the natural hones I am used to.

And: when it comes to japanese natural *finishing* hones, the japanese often think of the "hardness" of the hone as correlating (not entirely, but significantly) with the ultimate fineness of the hone. I.e., the hardest of all hones are best for finishing razors.

Just a few thoughts. Interesting discussion. Where be the Professors of Razor Science?