The ring of hardened steel

Tai, you can't tell us only half of your secret. Come clean now, which end do you have to smell?
 
Seriously though,… Using any or all of the five natural human senses to determine the hardness of steel, (or anything else for that matter),… is “anti-scientific” and practiced only by charlatans and witch doctors… :D
 
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Oh no...another can of worms for us science minded folks to dissect! :D

Actually, the first thing I do after I pull the blade out of the quench oil and wipe it down is pull my finger tips across the edge like I'm plucking a harp string. Maybe it's my imagination, but I can hear/feel the difference between a hard edge and soft edge with the same geometry. The hard edge seems to make a higher tinny sound. I don't know that it tells me anything useful, just something I do.

--nathan
 
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Come on, Tai. Don't be so humble. You know that you lick your blades when forging to see if they're at the right temperatures. ;)

BTW, I've also noticed the burnishing/polishing effect on the steel after testing with a file.

--nathan
 
is this after you take the knife out of the quench oil that you notice the brunishing/polishing effect?
 
bikermikearchery said:
Just messing around a bit I have made bells out of copper. These were very small bells. when first cast they were a bit flat. after work hardening them they had a much nicer peal.
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It’s very romantic and anti scientific,… but they also use planishing and “work hardening” to fine tune cymbals.
 
I thought about just leaving this simple and comforting but I guess I will make things more complicated and confusing instead. ;)

There are two methods of hardness testing to consider in this discussion- the Shore scleroscope type test, and the Sonodur type test. The Shore scleroscope uses rebound to determine hardness by dropping a 40 grain hammer 10 inches onto the smooth and level surface of the test sample and then measuring the rebound obtained. The Sonodur method is most interesting for this discussion, it involves pressing a diamond tipped probe against the sample which is electrically vibrated. The resonant frequency, or that of greatest vibration, in the metal is then measured and is translated into a hardness value in BHN (Brinell). Measuring the resonant frequency of a piece of steel sounds very similar to what one may get from sound waves.

Now having said all that, do I believe that a person holding up a blade and tapping it is doing anything more than making a fool of themselves?… not really. Years ago at an SCA event (you can always find somebody to entertain you with nit-wittery at those things), I kept my name and profession to myself while in the presence of one of their “master” smiths and was treated to an awesome display of skill. This buffoon assessed the quality of around half a dozen blades for folks standing around by holding them by the pommel and tapping the blade with his ring. He not only told the hardness, he used the sound to determine alloying and carbon content as well! When there were women present he could get incredibly accurate in naming all kinds of alloys I have never heard of even to this day! :D
 
Kevin R. Cashen said:
This buffoon assessed the quality of around half a dozen blades for folks standing around by holding them by the pommel and tapping the blade with his ring.
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Kevin,

I think you misunderstood when what we meant by "ringing" ... :D

Classic story. I wonder: Are other trades/avocations so steeped in mythology? It's fun in a sense, but then next week three guys will show up here telling newbies that the "ring test" is the only way to determine a blade's true worth...

Josh
 
Kevin R. Cashen said:
I thought about just leaving this simple and comforting but I guess I will make things more complicated and confusing instead. ;)

There are two methods of hardness testing to consider in this discussion- the Shore scleroscope type test, and the Sonodur type test. The Shore scleroscope uses rebound to determine hardness by dropping a 40 grain hammer 10 inches onto the smooth and level surface of the test sample and then measuring the rebound obtained. The Sonodur method is most interesting for this discussion, it involves pressing a diamond tipped probe against the sample which is electrically vibrated. The resonant frequency, or that of greatest vibration, in the metal is then measured and is translated into a hardness value in BHN (Brinell). Measuring the resonant frequency of a piece of steel sounds very similar to what one may get from sound waves.

Now having said all that, do I believe that a person holding up a blade and tapping it is doing anything more than making a fool of themselves?… not really. Years ago at an SCA event (you can always find somebody to entertain you with nit-wittery at those things), I kept my name and profession to myself while in the presence of one of their “master” smiths and was treated to an awesome display of skill. This buffoon assessed the quality of around half a dozen blades for folks standing around by holding them by the pommel and tapping the blade with his ring. He not only told the hardness, he used the sound to determine alloying and carbon content as well! When there were women present he could get incredibly accurate in naming all kinds of alloys I have never heard of even to this day! :D
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Good to hear you thinking so clearly... good point!

Keep up the good work! :)
 
mete said:
... a production test for bearing balls .This test is very simple but very accurate .It involves 'ringing ' in a way .The balls come down an angled shute, hit a hard metal plate , bounce up into a hole.Any ball not properly hardened will miss the hole !
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My balls must be way soft then, i miss the hole all the time...:D
 
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