Rockwell Hardness Tester

I figured I would join in this as I'm the other tester on the website. It's been quite a few years(maybe 8?) since I was on Bladeforum, though I'm pretty sure I remember most of the rules.

Some of you may know me from the other forums, some may not, I use the same username. I won't get into all my history here. I mainly came here to say, or to acknowledge to this forum the basics of our testing. I currently have access to a Mitutoyo HR-320MS at my current job, calibrated at 3 month intervals. Most of the data I provide to the website is through this machine. I also have access to a Starrett Digital Twin 3824 at the company that is currently partnered with the company I work at now, also calibrated at 3 month intervals. The company with the Starrett is where I worked at starting in high school at age 16, all the way to age 24. While both of our jobs aren't identical, Taylor is more into straight material testing and quality control, and my role is in machining and manufacturing to various industries, we both have worked with these machines many years in a professional setting.

The main goal of the project as a whole is just completely unbiased testing of knives. I don't have the ability to test the sheer volume of knives Taylor does, neither my current job nor the company we're partnered with would allow it. So I've basically been just testing knives I've been collecting again, mostly for getting into cut testing again, but that's another topic.

I just figured I'd join in and introduce myself for my first comment on this forum with the new account.

Basically all we want is unbiased ASTM E18 credible test information out. That's really the main goal of everything with this specific database.

-Jacob
 
TaylorHardness said:
Got my account to work. For some reason the confirmation email was going to my spam folder. I had JTR357 relay a message for me, as I felt discredited. The attempt to discredit me while not having an understanding on the subject matter at hand is confusing to me. Do you work in the materials testing industry by chance? @Knaferfang?
Click to expand...
Knaferfang- specific machines do not have their own specifications. ASTM E18 allows for conversions between scales (ie superficial to standard) in accordance with ASTM E140. Table 1 has all of the information you would need for this, assuming your blade steel is non austenitic. You would know this if you were to read the spec (ASTM E18) that you claimed I am not following. The “154CM” blade at 62 HRC is a clone knife, and I made a note in my data sheet that it may or may not actually be 154CM. “Mixing and matching data is not acceptable” is entirely incorrect. The mechanical testing industry allows for conversuon across the board in regards to different scales. This is entirely normal and a very common thing to do. My machine (Mitutoyo HR-530, not a Temu machine by the way) was calibrated professionally by a third party (I work in an accredited testing lab, it absolutely has to be). Your doubts are irrelevant to me, because you know nothing of Rockwell testing, as previously stated. I will leave a link where you can purchase a copy of ASTM E18, so you do not get it mixed up in the future.
Click to expand...

I am a retired aerospace materials engineer. So, yes. I do have such experience.

In my ~forty years of experience, a manufacturer will state which ASTM methods a machine can be used to satisfy. When I was working, if it was necessary to send work out from our lab, it was standard procedure to identify which machines would be used by the outside lab and confirm that they conformed with the the requirements of the test specification.

Are you aware that it is impossible to guarantee agreement between identical machines calibrated to two different Rockwell standards closer than +/- 1? Even if both standards are traceable to the national standard? If you are going to compare materials, then they both need to be tested on machines calibrated to the exact same standard. That's what I was getting at with the "Mixing" comment.

Conversions between methods are hinky, because you are actually measuring different attributes, then calling them equivalent. Yes there are tables for such things. I still question them. In my business, we did not use them. And as Larrin said, ASTM frowns on their use.

Frank R
Senior Principal Materials and Process Engineer, Retired.
 
TaylorHardness said:
Appreciate it! Thanks for making this thread in the first place. Kind of odd I have to immediately defend myself from a “supermod” who has no idea what he’s talking about, but whatever. I’ve been sort of avoiding this forum due to the moderstors I’ve seen, and the overall vibe I get from the people on here. Doesn’t seem like a very welcoming place, nor does it seem that a lot of factual information is being shared on here. I chose Reddit as my primary platform due to the younger general age demographic. The younger generation is typically more open to learning, but I’ll give it a shot regardless. Thanks again!
Click to expand...
Well don't let the door hit ya where the good lord split ya. 🤓


But in all seriousness, the older generation here on the forum has plenty of knowledge to share. Vast quantities of knowledge gathered over many hundreds of cumulative years. I find the old timer know-how to be just as if not more valuable than the "I did a 20 minute Google-fu and now I'm an expert" Reddit crowd.

They are grumpier though 🤣
 
Last edited:
I looked at Protech knives (only Magnacut was tested) and was surprised to see these high hardness values.
The lowest value was 63.6 HRC and the highest was 64.8 HRC.
That's quite harder than what I thought was the "optimal" balance (62.5 HRC) according to Larrin's articles.
 
I vote we start a new thread for the continued discussion of ASTM standards (if it must be continued) and let this one continue to be about comparing the hardness of various knives.

patrickguignot said:
I looked at Protech knives (only Magnacut was tested) and was surprised to see these high hardness values.
The lowest value was 63.6 HRC and the highest was 64.8 HRC.
That's quite harder than what I thought was the "optimal" balance (62.5 HRC) according to Larrin's articles.
Click to expand...

Protech may not be targeting optimal balance as much as maximum edge retention at the expense of toughness.
 
Ilikesharpstuff said:
I vote we start a new thread for the continued discussion of ASTM standards (if it must be continued) and let this one continue to be about comparing the hardness of various knives.



Protech may not be targeting optimal balance as much as maximum edge retention at the expense of toughness.
Click to expand...
One thing I should mention on that specific Pro-tech that tested at 64.8Rc, it wasn't a regular model. It was one of their $800 17-4 stainless bodied knives, which they claimed was initially made by their in-house maker. I had to return the knife to them because of the very strange tolerances on the body of it, it was unable to go back together properly (blade wouldn't open or close it scraped so bad, even prior to testing it just, disassembly and reassembly). So that model may not be a great representation of all their Magnacut knives. I've only tested their newer Magnacut, so I am not positive how older heats were run, nor am I positive if that's the entire range.

Excluding the $800 one that I had to send them to give to their in-house maker somewhat fixing to get it to open and close again, the range I've tested is 63.6-64.3Rc. It's possible there's knives in Magnacut by them softer than these, only 6 were tested(excluding the $800 one). But yes, they could potentially be sacrificing toughness for wear resistance on at least the models I tested (Mordax, Malibu, TR2 models).
 
Last edited:
Skylark427 said:
One thing I should mention on that specific Pro-tech that tested at 64.8Rc, it wasn't a regular model. It was one of their $800 17-4 stainless bodied knives, which they claimed was initially made by their in-house maker. I had to return the knife to them because of the very strange tolerances on the body of it, it was unable to go back together properly (blade wouldn't open or close it scraped so bad, even prior to testing it). So that model may not be a great representative of all their Magnacut knives. I've only tested their newer Magnacut, so I am not positive how older heats were run, nor am I positive if that's the entire range.

Excluding the $800 one that I had to send them to give to their in-house maker somewhat fixing to get it to open and close again, the range I've tested is 63.6-64.3Rc. It's possible there's knives in Magnacut by them softer than these, only 6 were tested(excluding the $800 one). But yes, they could potentially be sacrificing toughness for wear resistance on at least the models I tested (Mordax, Malibu, TR2 models).
Click to expand...
I would suggest that there should be a notes section (or similar) where that exact kind of information could be added.
 
Skylark427 said:
I think he means the main website, as that's likely where most people will go for the overall comparisons and results.
Click to expand...
Ahhh okay. I don’t have actual access to the website outside of adding information to the spreadsheet. If people have further questions about data on the website, they can refer to the spreadsheet first.
 
knarfeng said:
I'm not buying some of the numbers. Whoever heard of running 154CM at 62?

And some of those machines from which he is pulling data do not conform to the standard ASTM method for Rockwell hardness measurement.
Note: "Superficial Rockwell Hardness" is not the same measurement as "Rockwell Hardness".

The standard ASTM method for measuring Rockwell hardness of metals is ASTM E18. Look up the specs for each machine. If it does not include ASTM E18, then you are getting approximations or conversions from other test methods that are actually measuring different properties. Mixing and matching data from different measuring methods is not acceptable.

And how were those machines calibrated? Were they in calibration? Were the calibration standards traceable to the national standard?
Click to expand...
He works at a NADCAP certified testing lab
JTR357 said:
Here's the Strider's that were tested. With their lowest being the S30V at 55.7. He states the machine he's using & the pin. I know nothing about this. I just thought it was interesting. Apparently he's getting a lot of flack from manufacturers which is to be expected. The machine he's using is a Mitutoyo HR-530. Is that an accurate machine?
Click to expand...
Another thing to remember is that these knives were not purchased from the manufacturer with traceability. Sharpening with too fine of a belt is enough to temper some heat treats, lowering the HRC
 
~Tu~ said:
Another thing to remember is that these knives were not purchased from the manufacturer with traceability. Sharpening with too fine of a belt is enough to temper some heat treats, lowering the HRC
Click to expand...

Im not sure I can buy this. The testing area should be on a flat, quite away from the cutting edge.

I totally buy that power sharpening can affect the temper at the edge, but to what degree and how far away is the issue.

I think you'd have to REALLY go sideways to have much appreciable variation in the testing area.
 
J. Doyle said:
Im not sure I can buy this. The testing area should be on a flat, quite away from the cutting edge.

I totally buy that power sharpening can affect the temper at the edge, but to what degree and how far away is the issue.

I think you'd have to REALLY go sideways to have much appreciable variation in the testing area.
Click to expand...

That's a good point, T TaylorHardness and S Skylark427 , and maybe I missed it on the website or even in this thread. Where did you measure ? On the tang ?

Thanks for all that work, BTW.
 
J. Doyle said:
Im not sure I can buy this. The testing area should be on a flat, quite away from the cutting edge.

I totally buy that power sharpening can affect the temper at the edge, but to what degree and how far away is the issue.

I think you'd have to REALLY go sideways to have much appreciable variation in the testing area.
Click to expand...
Easy, it was inly an example of unknown blade history
 
You must log in or register to reply here.
Back
Top