tester

I have a low cost one. I use it mostly on blades with no differential heat treatment that are heat treated in my heat treating oven.
 
It was around $900. a couple of years ago. I got it from http://www1.mscdirect.com/CGI/NNSRHM.
A Clark Rockwell tester USED will cost around 6k, I was told this by the the company that services our Clark tester.
He also said the inexpensive rc tester would be good for knife making and the high cost of a upper line tester would not be worth the small increase of accuracy in his opinion.
 
loussharp1 said:
It was around $900. a couple of years ago. I got it from http://www1.mscdirect.com/CGI/NNSRHM.
A Clark Rockwell tester USED will cost around 6k, I was told this by the the company that services our Clark tester.
He also said the inexpensive rc tester would be good for knife making and the high cost of a upper line tester would not be worth the small increase of accuracy in his opinion.
Click to expand...

dave when you test a run of knifes, to me that would be 3 -4 , do you see any difference if they were all the same steel and quenched the same way?or do you test them all .
 
I test them all at least 3 times in the same area. I like doing it where the bolster is going. Usually they are within a point or two of each other.
I like using A2 tool steel and a Rockwell of 58-60 on the C scale.
 
I've got one of the 170lb. ones from Grizzly. Checked it with 3 or 4 certified test blocks and seems to be right on. I'm usually pretty skeptical about instruments from over there.
Cost $900 to put it on my doorstep (Springfield Mo. to central Wis.)
Ken
 
(Second post - don't know where the first one went?)

I have a nice Misawa Seiki tester that I got cheap from a metal fabricator in New Jersey who went under. I got it and two boxes of penetrators,anvils, and accessories for $80 plus $100 shipping.

With all that, I rarely use it.
Rc is very important in aircraft turbine shafts, but it is not the be-all and end-all of knife blades. If a blade is Rc 63 or Rc 57 it may be good or bad....depending on what you are trying to do???

It is nice to test a blade occasionally...to check on your HT....but the real test is in the use of the blade. If the steel was well chosen...and the HT was properly done....and the blade geometry is right for the job.... the Rc will be about where it should be, and the blade will cut as it should. Miss any of these and the other one won't matter much at all.

I will repeat my mantra again -
The more you work you put into your knife before you put a tool to the steel will pay off in a better knife. Planning, research, and following through are the tools needed more than a machine that may or may not give an accurate reading.

Eliminating the random from random results always will yield a better blade.
Using a known steel...
Researching and developing the proper HT....
Staying within the bounds of your abilities and equipment....
Picking the right blade geometry for the job....
Following through with all the above.....

All this will give you a lot more to go on than a number inked on the tang.

Stacy
 
I test every blade numerous times during the heat treating process and record the data in my book; bought a Rockwell tester within a month of getting my first furnace back in 1985 and have used it on every blade since.
I look at it as another tool in overall process control, and for just one example has helped me diagnose a bad furnace thermocouple which would have otherwise gone unnoticed. It helps avoid randomness which could fly under the radar without the testing.
But then, that's just the science geek in me. To each their own.
 
Mike,
I agree that it can be a valuable tool to a maker in perfecting his/her process...but it is not an indicator of a good knife in itself.
Stacy

Hey, Ol' buddy...I heard that you were now a famous engraver!:D
 
bladsmth said:
Mike,
I agree that it can be a valuable tool to a maker in perfecting his/her process...but it is not an indicator of a good knife in itself.
Stacy

Hey, Ol' buddy...I heard that you were now a famous engraver!:D
Click to expand...

I personally like using hardness as a monitor of repeatability, as well as being able to fine tune a blade hardness to specific purpose. It is, of course, not the sole indicator of a good knife, but is a valuable tool for me in every knife.

I am slowly learning some engraving. I'll never be an engraver per se, as there are aspects of the art, like lettering, which hold no fascination for me. Eventually, hopefully, skills will progress to where I will be able to put it on a knife. It will be a takedown knife, of course, so botched engraving can be readily replaced. :)
 
I'll just echo both Dave's and Fitz's posts...

I looked for something like a Wilson for several years, but decided the cost was awfully hard to justify. Phil Wilson's article about that very same notion helped make my decision.

I agree with Stacy in the idea that Rc is not everything, but I am with Fitz in that it's another way to cut down on the variables.

As a side note, before I bought my tester, I would take blades to the local machine shop and get them tested for $2 each (on one of those $6k testers :) ).
 
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I also agree with Stacy and Fitzo for both reasons respectively, they are on a nice balanced midline from two extremes. On one far side are folks who know very little about steel, knives or making knives but they have heard of Rockwell so they cling to for security and to show their prowess off to those who know even less than they do. On the other side of the range are the queen Gertrudes (the lady doth protest too much) who have a deep seated need to totally dismiss Rockwell hardness, this could very well be the result of not liking what the test said about their knives, or an inability to grasp a total understanding of the test.

A hardness tester is a tool quite a bit like a powerful piece of software is on your computer. When you first open it you can decide to throw away the manual and blindly plunk on a program that has a learning curve steeper than a cliff face, or you can make the effort to become truly proficient in its use. Most folks will only ever use one or two functions of that powerful software and many of those will most likely proclaim it as junk since it never worked for them; they tried using Photoshop when they only wanted to get as deep as a Windows paint program. Others will roll up their sleeves and get serious enough about the software to unlock its full potential for productivity.

The power of the Rockwell test is in giving you a precise reading about a very specific property, the fact that it does not tell you everything you need to know is its strength! As tools, tests that claim to tell you all or many things that you need to know in one shot are a lot like tarot cards, they work the best when they tell you exactly what you want to hear.

If you are working with equipment that allows you to give all of your blades the same heat treatment, test them, and then bump your temps up or down by 25F to test again, then the Rockwell tester can be a very powerful tool. If all you have is a torch and a bucket of oil, why do you want a state of the art oil filter wrench when all you have is a horse and buggy?? Not that there is anything wrong with a horse and buggy but the two don’t go together, and the buggy driver has no business telling the formula one mechanic what he does or does not need for tools!

A Rockwell tester will only tell you what the penetrative hardness of a piece of steel is. It can’t tell you anything about grain make up as in overheating things (in fact Rockwell numbers go up with overheated steel) or abrasion resistance. But it can be invaluable in fine tuning your heat treating process so that you can get the most out of it. People who feel that all they have to say about their knives is the Rockwell hardness just don’t get it, but on the other hand those who are too quick to dismiss the test reveal an equal lack of understanding or insecurity. Tools are tools, it is how we use them that determines their value.
 
I should have pointed out that many of my blades now are differentially hardened, and thus the test of the tang tells nothing about the hardness of the edge or spine. I do occasionally test a blade that will not be finished (destruction testing) on the spine and as close to the edge as can be reliably done. Near-Edge tests are a bit of a trick to do reliably. Another thing is my use of the word occasionally, in which I mean not on ever blade, but when needed.

The great thing about this forum is the wide range of experience ( experience is far more valuable than opinions) is available. Mike is a good make with a technical background, and his methods are scientifically based. I come from a similar background as Mike (we both were chemists), and started out with all the testing and QC stuff I could get/make. I have changed (mostly in the past year or two) due to the influence of the point of view of those like Kevin, mete, .....and even Tai Goo. These, and many others here, really know their stuff. They do the research, assemble the information, and pass it on . I have learned to trust my workmanship more and my machines less. This is not because the machines are useless (try to take them from me and we have a fight) but because I have used them to develop repeatable results that require only occasional re-testing.

There are many other experts that started with their idea ,developed a theory of knifemaking to prove the idea, and stayed with that to this day. They may get good results, but it is more due to their repeated tweaking of the process (and inadvertently improving it) over thousands of knives than it is due to the truth of their theory.
 
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