How is hardness of a blade determined?

DeSotoSky

DeSotoSky

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Is it a simple of difficult thing to determine the Rockwell hardness of a knife blade?
I really don't know how it's done and suppose I could Google it but then, what would we talk about here? .... :)
I would like to determine the hardness of one of my counterfit knives for a comparative study.
 
DeSoto,

I think you had better start saving your pennies to buy the testing equipment.
 
The Rockwell Hardness test method is conducted on a machine which uses a steel ball to thump & penetrate into the blade and the depth measured. Deeper penetration = lower hardness, ex. 54 rc (rock well scale).
The better quality machines take readings from 2 points the China machine measures from one point. The blade is clamped in and the stroke begins from a definite / measured pressure setting. The China machine new I've seen them offered at 1,500. The testing plate, ASTM standard is +/- 1. So, some room for error. Still, this is within tolerance. Hence, a knife blade could have for example a reading of 59 rc on one machine and 61 rc on another, all being within tolerance range. If this were the case I'd call the blade at 60 rc. DM
 
Years ago when working on firearms the local gun smith would run a hardness test on an action if I asked. His machine was older but would, as Dave said, measure the depth a ball would penetrate into the metal with a known force.
I would think some of the machines should be around.

Out of curiosity would the complete blade be the same within reason or is the heat treatment localized?
 
My older son, mechanical engineer, did the test at the shop where he used to work (ww mfg ag equip). Unfortunately, he moved into tech... The test put a couple of small round randomly placed (to my eye) dimples into my target knife blade. The result was expressed as a narrow range of Rockwell hardness. I will ask him, you know his lovely wife is also a mech. eng. working in tech. so I will ask her tomorrow when I see her, if he still has access.
 
Desoto, I can still find the service available. Phoenix Heat Treaters may still do it and they would send back with my blades a certificate of method of heat treat and hardness test. I could always find the divot on the blade.
375, If the heat treatment is done in a oven the same hardness should be found throughout.Within +/- 1. If done with a torch the hardness is more localized.Unless they are very good at forging. The machines are available, I run across them at times. But before buying procure a knowledgeable person familiar with that machine and have it thoroughly checked. This type fellow isn't found in your local machine shop. DM
 
David Martin said:
But before buying procure a knowledgeable person familiar with that machine and have it thoroughly checked. This type fellow isn't found in your local machine shop. DM
Click to expand...

Thanks for the responses. I have no interest in "buying" a machine, only of having 2 blades compared.
I wanted to compare a counterfit Chinese Vanguard to a real USA one.
It's something that interests me but most would consider a lame project.
Not something I would spend a lot of money on regardless.
 
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You can search around and find a shop that has a hardness testing machine to get them tested. Carry them over and have them tested. Then be glad if it's only 5$ a thump. DM
 
I worked at a fabrication shop and the machinists had a rockwell 'C' tester. Pretty neat stuff, took a couple knives in for testing and was very happy that the hardness was in the range advertised.
 
Thank you Mr. Hubbard for chiming in on this. I forgot to mention the file option. Yes, that's a good option. I recall when I was interested in that set they ran 200$. I wouldn't doubt more now and some learned skill is needed in using them. Plus, the kit is set up not in individual numbers. I wanted a set with a 58, 59 & 60. This would have run much more dollars. DM
 
DeSotoSky it is no problem for the engineers to test both knives for hardness. They will be returned with dimples, however. Send them to me if you want to proceed I am happy to assist and ready to learn. Emailed you my address.
 
oregon said:
DeSotoSky it is no problem for the engineers to test both knives for hardness. They will be returned with dimples, however. Send them to me if you want to proceed I am happy to assist and ready to learn. Emailed you my address.
Click to expand...

Thanks, you've got mail.
 
Cool. This is gonna be fun. Hard data on the fakes vs real. We shall see what Rockwell tells us. Good idea.
 
LOL.

Neither engineer knows fakes from snakes. They will only know that they are testing hardness on two knives. Branding or authenticity is irrelevant to them and only correct procedure and results count. I will not open their eyes so double blind test! Pun another one...
 
Here’s a Puma IP folder I recently picked up with the hardness test “dimple” proudly labeled:

PUMA IP Paloma.jpg
 
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