Thread: Common Rockwell

maybe Tim Harner is a brother

i would bet that most blafdes fall in the 57-60 range and the new guys and custom makers are running a bit harder then that (think around 59-62)

Samuel,

After soaking at the right temperature, the edge is quenched first, then the rest of the razor is slowly lowered into the quenching medium - this leaves the edge harder than the spine.

There are some videos of Mastro Livi doing this on the 'InterWeb'.

For commercial, bulk production, razors, I do not know if they are treated the same; possibly/probably not due to the cost etc.

Dovo & TI used to use (still do ?) molten lead for their heat treating process, so I suppose practicality would dictate that they would quench the entire razor at once.

Have fun !

Best regards

Russ

Imo, blades at 65 HRc are really not fun.
Even at 62 HRc, they can be a bitch to get a bevel on and get them shaveready. 65 would be many times worse. So all in all I think 62 should be the maximum hardness for a blade. Going harder than that is imo pointless and counter productive.

Originally Posted by Adam G.

Something to bear in mind. Do not get too hung up on Rockwell ratings alone .... Not meant to be more confusing, but thought another perspective may help explain the differences in performance between brands, and even different razors of the same brand.
Regards

A very good refining point in the discussion. And without ever having been to my shop, you correctly identify one of my practices with a new batch of steel.

It wasn't until about the 1940's when industrial steels (big bucket stuff, the lab fellows were a little further ahead) were even concerned with chemistry. Before then, it was a matter of following more ritual than anything. Now chemistry drives everything.

Sorry, I couldn't resist jumping in.

Don't be overly concerned with Rockwell hardness readings. The Rockwell C scale is only good for plus or minus one point anyway. That is by the specifications of the test. A blade that is advertised as 60HRC could be anywhere from 59HRC to 61HRC. A good machine, with a good operator can keep things to within 1/2 a point. But even then, things will vary on a given machine on a day to day basis. Testing against a known standard is required with every batch of tests.

Rockewell C specs. call for a minimum thickness of 0.030". So testing an edge requires a microhardness tester (Yup, I have one). You will see those values as Knoop or Vickers with the associated weight used for the test. You have to be careful with microhardness readings too. I can pick out individual carbides and get the equivalent of 67HRC every time.

Hardness values only tell you about the steel's ability to resist a dent from a diamond pointer, under a given weight. You can also correlate other things from hardness tests such as tensile and impact strength. On a practical basis, it is most useful for research and checking to see if you botched the heat treat.

For razors, things like abrasion resistance, carbide size, retained austenite, etc... also come in to play when discussing sharpness, edge holding, ease of honing, etc. Hardness is only one of the variables. Hardness is important, but the other stuff is just as important. As an example, a 62HRC blade of 1095 is much easier to hone than a 59HRC blade of 154CM.

Edges may be harder than spines, or not. That depends on the type of steel and the heat treating techniques used.

The best, real test of a razor is to hone it, and shave with it. Lynn's correct again.

If you want to jump in to the morass of metallurgy, a good place to start is Metallurgy Fundamentals by D. Brandt - Amazon.com: Metallurgy Fundamentals (9781566375436): Daniel A. Brandt, J.C. Warner, J. C. Warner: Books

Tim Z.

Originally Posted by cpcohen1945

From www.customshaving.com , in a description of Tim Harner's custom razors:

just to clear up a bit
the site that you got the quote off of was www.classicshaving.com
i am on there as Lloyd R Harner and Tim Zowada is the man that showed me the way.

since it was quoted i thought i should make it right