Etches and the people who love them

Thanks Rex, I was kind of wondering if we were going to hear back from you. I think that what you pointed out is something very important to realize. The fact that etching is a powerful tool in learning about making a better blade really makes sense to me.
 
This is actually more of a question on grain direction and its potential effect on cutting performance. If one were to take a 1.5" round bar of 52100, twist it, flatten it, then forge a blade, in theory what was the end grain of the round bar would now be exposed along the cutting edge. Could this increase cutting performance?

Also, I know springs can develop small stress fractures, etc. making them poor for blades. What about bearings? Are any of the stresses to which bearings are subjected likely to compromise their integrity as a blade? My instinct says no, that bearings are subjected to wear but not flexing and other negative stresses? What do you all think?

Thanks,

John
 
Originally posted by John Frankl
Also, I know springs can develop small stress fractures, etc. making them poor for blades. John
Click to expand...

I've been wondering about this issue of springs developing fractures myself. I would have guessed that if you annealed the spring material, and then took it to forging heat, forged the piece, that you would completely "heal" any of those tiny cracks/fissures. But I could be way wrong on that guess.

Would appreciate hearing what you forgers know in this area. Thanks.
 
Until I met Rex, I could not allow myself to believe that these unseen faults could not be healed by the forging process. When a little chip blew out of the side of the blade on a 90 degree flex, I blammed it on an error on my part. Kept searchiing and trying to explain what I did wrong.
Then came Rex, he explained the nature of the failure and how and why. Suddenly the mystical was reduced to reason. They are little miniscule faults, at possibly the microscopic level, but combine with adjacient formations to get serious.

Rex will make more sense out of what I have tried to describe. I have seen them, chased their shaddows and only after talking to Rex caught their scent and they are conquered.
 
Yes bearings can and do develop microcracks and other faults in their working life.
Thats why they are replaced on a regular basis. Experience has shown they have a useful life and most importantly,when they fail its usually catastrophic. A bearing is probably the most reliable tool ever made by man. It has to be designed and manufactured to withstand forces that want to both crush and explode it at the same time. The fact that they last for 10s of 1000s of cycles at operating conditions is amazing.
Not all bearings will develop faults before being replaced but how can you tell which one is golden?
Most microfaults will heal with proper forging but again, how can you tell?
Not everything that goes wrong in a finished blade is the makers faukt. Sometimes you skate a gold medal routine and the vote is rigged. Analyize what went wrong and be honest with youself.Nothing is ever a failure if you kearn from it.
Rex
 
Beautiful thoughts Rex: One time I threw away the thoughts of the science of metals for I found they were not directed toward the art of knife function. Honesty of the spirit of the knife was not available to me through the existing texts. Now I find that the science of metals comes to explain the spirit of the knife, thoughts, that after our exchange of information suddenly became my friend, illuminating truth. So I ask you what comes first, and how can the knife maker who seeks the best avoid the pit that holds the traditions of performance hostage?
 
hi, i am a stock removal maker and have Paul Bos heat treat. 440c, ats-34 and BG-42. i have heard this about moving or alineing the grain in steel by forging, what i don't understand is if you heat the steel to a non-magnatic for heat treat. are you not also normalizing the steel to a large degree, and there for losing this alinment of grain sturcture that has been worked into the steel?
 
That is also my question to knifemakers who forge.

In my business we design and manufacture steel rolling mills. The forgings we use in highly stress parts are hot forged and cooled for use as is, no heat treatment after forging.

Bringing steel above the transformation temperature changes the crystaline structure, does it also change the grain flow from forging?

Is there a source for photomicrographs of forgings before and after heat treatment?

Regards,
FK
 
Hi Rhinoknives and Fk.,Good Questions.
Heattreating steel does not remove grain flow. The crystal structure does change but it is in large part influenced by the underlying grain.
An excellent example of this can be seen in Ed Fowler's book KNIFE TALK.
On page 113 he has a story on how he etches bearings to show the flow pattern of the grain in the steel. This flow pattern is the result of the mechanical work that went into the making of the bearing. This bearing then underwent a complicated heattreat and temper cycle. Yet years of hard use later the evidence of its birth is still visable.The heattreat may lessen the dramatic appearance of the pattern but cannot remove it .Just as we all carry the scars of our formative years,steel also shows the process which shaped it.
Take care
Rex
 
i dont have a copy of mr. folwers book, but i have plenty of scar's (still collecting them) your anwser sounds like saying that seeing erosion on sandstone make's the composition of the sandstone differnt. i am a dexlexy? california boy, but it still sounds like if you change the chrystalline matrix by bringing it up to critical temp, would'nt this render the bathtub ring moot? :D
 
The debate has raged for a number of years now about heat treating methods versus blade performance. Empirical tests such as rope cutting and ductility via being bent in a vice are obviously beneficial but are prone to significant variability.

Much is spoken of grain structure and grain growth/reduction during the forging process and heat treatment. Etching a blade with acid is necessary to expose grain structure, but examination with the naked eye yields only the grossest of conclusions. Photomicrography of the cross section of a blade would provide a very dramatic indicator of the validity of current theory regarding the superiority of forging, mutiple quenching, etc.

Scientific examination of a blade would be incomplete without these micrographs, so I am assuming they have been done to validate the conclusions. Alot of information could be transferred by publication of these photos without relying on the frailty of verbal descriptions.

continued in subsequent post.....
 
to continue my request....

I do not like being a gadfly, but after thirty-plus years as a scientist I am very habituated to the scientific process, which requires that proper data, statistical verification, and then conclusions be presented along with experimental procedures.

Much has been accomplished by Ed, Bill, Rex, and others to further the knowledge of "blade science", and they are to be lauded. However, technology is such that it should be relatively easy to produce the data (photos) necessary to explain the empirical data. Thus, without intending to be too much of a jerk, I am requesting that if such micrographs of grain structure are available, that they be published through this forum, and if not, that they be obtained in order to verify the claims being made.

I write this with no rancor nor am i questioning anyone's conclusions. I simply feel that more conclusive data should be readily available and thus are necessary to further refine our craft.

Best regards,
mike fitzgerald
 
Hello Mike Fitzgerals: Good question and thanks. Sorry, but we do not have the technology to post photomicrographs. Photomicrographs of some blades were published in Knives 2002 on page 56. I would like to mention, first comes a blade that meets the expectations of high performance, then the science to explain its nature. We wish to do both.
 
hi, at the last blade west show i was the big guy that said you were my faviate knife writer and told you how funny you article about the supermarket that was slow pay on some beef, so you parked a truck load of dead sheep up wind of the store, and they suddenly had a check for you.LOL i know you talk to lots of folks and if you say that there is a inprovement by forging i belive you. i would like to see the documention as well. will get a copy of your book next time i see you. take care :)
 
Rhinoknives: Thanks for the kind words. The last thing I want to do is mislead anyone. The next few issues of blade I will be discussing how and why what happens happens. We are into a new phase in our experiments, and will hopefully be bringing more interesting stuff to the table.
 
Hello
I have several dozen photomicrographs of some of the experimental blades we have destroyed. I also have hardness tests ,chemical anaylsis and other metallurgical tests. Not all test samples had photos taken. I agree that science can explain what is going on with the material and its processing. The days of voodoo and superstious old wives tales are giving way to education and understanding.
Many of the practices in use DO have a sound basis for why they work. The trick is to figure out What is happening. An example of this is When dozens of makers, working indepentantly of one another, report that multiple quench make a better blade.Thats a good indicator that something is going on.Experiments sre designed,samples taken and evaluated and progress is made. I don't have a scanner but if you send me your address I will send some photos to you to post.
Knowledge should be shared so that all may benifit. If you have a specific question let me know and I'll try to answer as best as I can.
Take care
Rex
 
Hello, Ed and Rex,

Thank you for your replies. I appreciate your offer of sending me photos since I failed to realize that BF does not have graphic capabilities. As I stated in my private e-mail to Rex,

"I hope that the spirit of scientific "skepticism" is not interpreted as an attempt to dispute what you folks are reporting. Far from it, you pique my interest to gain a more complete insight to why some blades are superior to others."

You and the others who seek to scientifically support what is observed in practical application do us all a service, and I hope all join in an appreciation of your efforts.

Thank you again for your responses.

Sincerely,
mike
 
Most of our experimenting was done on our own hook. We had no government grants or university backing. A few clients have provided funds to support our efforts and I am grateful for their gifts. Many other clients supported our efforts when they purchased our knives, again THANKS to them we were able continue.

Things would have gone much faster with greater financial backing, but we were able to do it using practical methods of evalualtion in our shops. This is due to the fact that a knife is a simple tool whose performance can be evaluated utilizing simple methods. The scientific part is much more demanding but sure makes it nice when it is available. Rex has provided the science and continues to look to the future.
 
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