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Author Topic: Questions about practice and procedures  (Read 13214 times)
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davidm
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« on: September 29, 2007, 11:49:45 AM »

Ed,
Excellent video!  L6 was mentioned as another steel, other than 52100, to possibly do future experiments with.  Why L6, is there something about it that give it excellent properties? .. or has it not been refined and worked with the same as D2 which has been a favorite of other makers. 

How has the standard heat treating, your heat treating changed over the past, especially since 2000 when you switched from the bearings to the bar stock?  Are there more thermal cycles being done, or is there more change going on in the times, learning why 35 sec. quenches provide the optimum amount of time, for example? .. or is the consistency of material the biggest advantage. 

What was the standard process of this when you studied with Bill Moran, is there a method of it that you wrote down, or remember the details of.. I wonder his opinion, for example of the multiple quench, I remember you wrote that he emphasized the etching of the blade to reveal the grain structure.  Is that because he did it on his own knives? (.. I do not recall ever seeing one of his knives, in recent memory, that was etched)

Have you been forging 52100 since 1989, or 1987?  do you remember?  I have one knife that displays all the characteristics of a forged 52100 knife, the original owner said he bought it from you in 1987.  I do remember seeing knives made earlier that were not etched, having a mirror finish.. these are 5160, or D2?  .. in the mid-early 1980's. 

Lastly, was it in 2000 or before that when you started working with Rex? .. how long was that process where you started experimenting with the bar stock and when you first started selling the knives?  .. I only remember the 2000 benchmark. 
Thanks, 
David    

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Ed Fowler
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« Reply #1 on: September 29, 2007, 03:29:54 PM »

Good Questins David!

The first letter I have from Rex is dated Feb. 26, 1999. He had just reviewed my DVD and our colaborabion started then. Like you stated we started working with the bar stock soon after that.

In the DVD I talk about L-6, I believe it could be worked up into great knives. I neglected to mention that John Deer 5160 is another great preformance steel. I don't know about L-6 and won't have enough time in my future to work with it enough to know. I hope that some new young maker decides to work with it and spend 10 years working it up.

Rex and I had a lot to learn, we had to educate each other and ran into many questions, had a lot of dismal failures and today continue to learn exponetially. In his first letter Rex asked why I felt multiple quench worked so well, it was only in this past year that we found more information about what we have been doing for years.

Rex did a jominy test, using multiple quench and we found that the hardness penetrated further. This was a big learning experience for it explains much more than simpel pentration. We may not be able fully explore the science, but we can enjoy the difference in performance. This is the main message of our DVD, not only what we are doing, but how the bladesmith can experiment in his shop and develop high endurance performance blades.

I will continue to respond to your questions, this is all I have time for right now.

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Larrin
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« Reply #2 on: September 29, 2007, 05:28:50 PM »

L6 is an extremely tough steel with surprisingly good wear resistance (probably not far off from 52100 in wear resistance, actually). The main problem you might have with it is it's so deep hardening it might be difficult to do a differential hardening on it. Hardening with a torch means the spine would never be heated up which would reduce that difficulty though.
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radicat
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« Reply #3 on: September 29, 2007, 06:54:55 PM »

I too took notice of Ed's mention of L-6 as another steel with possibilities for more research. I also noticed
a quick glance at Ed from Rex when he said it. I thought "That metallurgist didn't expect to hear that".
So, I set out to learn more about this steel. And, I take notes whenever I read about it or see a knife made from it.
We know it was used for saw blades more than any other steel. Disston saws and many other woodcraft tools were made from it.

I remember when I was a about ten years old when my father took me to watch the cutting of logs at a
saw mill in the mountains of New Mexico. The huge band-saw blade was ripping the logs with ease and a lot of noise. I asked my father how long that blade could do that : "All day. That blade is made of a very good steel." . He went on to explain that each evening a sharpened blade was exchanged for the next day. If the blade failed by getting hot and/or dull many men would have been idle until it was changed. He knew this because he was a master carpenter that had done it all when it came to wood.

One interesting thing about L-6 is that it has no manganese, which is supposed to aid hardening. But, it is known to be easily hardened (as Larrin said) . It does have nickel for added toughness.

The steel was used in many products that one can find as scrap metal, as well as old blades of course. Boye made a lot of his early knives using old band-saw blades. They are the right thickness for use in stock-removal.

The following quote is from a great article by Joe Talmadge on steels.

L-6

A band saw steel that is very tough and holds an edge well, but rusts easily. It is, like O-1, a forgiving steel for the forger. If you're willing to put up with the maintenance, this may be one of the very best steels available for cutlery, especially where toughness is desired. In a poll on the knifemakers email list back in the 1990s, when asked what the makers would use for their personal knife, L-6 emerged as the top choice.

http://www.zknives.com/knives/articles/knifesteelfaq.shtml



« Last Edit: September 30, 2007, 11:52:15 AM by radicat » Logged
Ed Fowler
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« Reply #4 on: September 30, 2007, 10:16:39 AM »

To continue answering your questions David:
The consistency provided by our steel being all from the same pour has allowed an understanding of events we have developed. Before other unknown variables shaded our work.

For example the critical temp soak, 2 hrs for every linear inch to the center came about when one of our bars was accientally overheated. At that state, 3" x 3" x 10" we were able to find a soulution to variability. Last week at Portland, we found that it also applies to 1095.

Consistency and Rex's work in the Lab. has allowed us to work on one variable at a time and our understading has grown.

The hardening with Bill was a full hardening with a soft back draw. He knew about the regulator block for differential hardening, but we did not have one where we were working.

Bill did not suggest the etching of blades other than Damascus. the etching of 52100 blades and a very few 5160 blades just kind of happened. I rember reading in one of Ken Warners annual publications where he commented on an etched 5160 blade and wondered why?

I also wondered why and started working with it. The information that followed was and still is an essential step in knowing what you have achieved in blades. Etching all blades makes a better heat treater out of the maker. It provides immediate feedback as to the quality of your forging and hardening accomplishment.

Bill did not participate in the multiple quench experiments. We discussed it, and he was interested and was going to work with it, but I do not know if he did.

In the 80's there were very few D-2 Blades, I quit D-2 after the forging seminar with Bill. Most 5160 blades were mirror finished, a few may have been etched.

I carried the first 52100 blade for some time before I offered them for sale, I wanted to make sure they were worthwhile. I also destroyed many blades before I finished a knife with the ball bearings.

The blades of today have many more thermal cycles, are all forged at lower temperatures and some special events like the 30 second post forging cycles.
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davidm
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« Reply #5 on: October 04, 2007, 05:44:20 PM »

Ed,
What is it that allows your knives to make so many 180 bends?  And, the edge being the hardest area, most likely to crack, why can it withstand the extreme abuse? .. what makes it not crack?

Did you ever have Rex examine the knife blade in the video to see why it seemed to show a kind of "maturing" process, not cutting at all, then after months it cut very well?

I've been curious about what Wayne Goddard is doing with the new friction process he's working with where pressure is exerted at 8000-10000 lbs. and the steel is (melted?) sheared away.  It makes me wonder what exactly is happening in the steel to cause the extreme hardness?  And, he says it's less brittle than other knives he's tested in the edge area, made of the same D2 steel.  Seems contradictory that something could be harder and less brittle.  I just wonder if you can offer some comment about what might be happening to make that the case.
In theory, would the grain size/edge area of something done be refined, small through pressure? Would it have qualities of a forged knife?
Thanks Ed!
David
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Ed Fowler
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« Reply #6 on: October 04, 2007, 06:24:20 PM »

What makes it not crack? - First variable is the steel we use, good stuff!!

Next comes all the steps you saw in our DVD, ultra fine grain, the result of low temp forging, many thermal cycles, the 30 second quenches all promote uniformity. Then the tight hardening cycles and 24 hour cycles. All contribute!  Rex and our good friend with the phd's understand the science, I only know how to make it happen.

The answer as to why the blade increased in cutting ability seems to have to do with time and maybe stress. An experiment reported in the 1940's by the Battle Memorial Institute suggests some answers. It has to do with time and prestress.

It all comes down to alloy banding, uniformity, fine grain and carbides.

I have not had the opportunity to test the blades they are making with the friction fusion technique, the title friction forging is misleading. I do (from reading between the lines of their reports) have the feeling that the blades are meant for fine slicing, not the kind of work we put our blades through.

Do they have the abilities of the high endurance forged blade knife? I don't know, maybe one day I will have a blade to test and we will see.

They are seeking to achieve the same thing we have been seeking, what Rex and I have been talkng about for 10 years, maybe they are better, maybe they are not.

There is a lot to learn, I believe much awaits in the future, I don't think the answer will be a quick process.

Grain size is not the only variable to seek, success comes through the matrix that supports strength and toughness. A uniform grain size of 14 would not be as tough as 14 and finer, in theory at least.

Food for thought:
As to new stuff: General Patton once commented about one of the bible heroes, Samsom, killing the enemy with the jaw bone of an ass. "Once the story leaked about about the lethal potential of this new weapon, the demand was probably so great that no donkey within miles dare brae!"
« Last Edit: October 04, 2007, 07:38:07 PM by Ed Fowler » Logged

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radicat
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« Reply #7 on: October 04, 2007, 10:21:23 PM »

I think the limitations of the process of Friction forging will keep its use in the flat grind realm for some time.

As for the food for thought, I'm sorely tempted to crack a joke, but I won't.

Keep thinking and asking David. Great discussion guys.         Clay
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davidm
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« Reply #8 on: October 05, 2007, 12:29:45 PM »

Thank you Ed and Clay,

The thing about the matrix your heat treating does, making it possible for the extreme bending.. it must be something I didn't even think,  that the matrix and banding extends throughout the hardened portion of the blade.  So, a similar 52100 knife made fully hardened with an edge of the same hardness, both knives having 60 hardness, while both knives may be similar in that way, the one with the more sophisticated heat treating will endure abuse and the other one will likely chip (because there is no matrix to support it).  Is that right? 

I remember years ago on the phone once you told me Ed, that the newer knives were on average better than your older knives because of the uniform consistency but that they would not compete with the best of your older knives.  This was about 7 years ago, and I don't remember what prompted the question about it.  Are there old knives, steel is nitrogen free, that have more advanced performance and compare to the new knives today, or do most (because of increased knowledge of what makes the best results) fall into a category you passed long ago regarding performance? 

For myself, I love the older knives.  Call it sentimental.. something about the art of the way you made them.  Just beautiful and they seem to define your style so well to me.  I did notice at Blade Shows 2000 and on, you kept carrying your old knife well beyond the time you were making newer, perhaps better performing knives?  .. so, you must feel that it served all the needs you would have. 

In newer knives, I do notice a lot of structural changes, edge geometry, thicker blades.. most of the older knives exhibit thicker blades.  The mod. Price grind, giving the knife the fullest design advantage. In testing did that dramatically increase the performance of your knives?

In regards to bending resistance, how have the newer knives of the video changed compared to the older knives made from bearing steel.  Rex made the point that because of the matrix and carbide banding the steel resists the bend, doesn't want to bend, and wants to return to straight.  On older knives was that same characteristic exhibited, or do you see an increase in resistance, or spring also?

The Modified Price grind, if I remember, I do remember hearing you say something about how it increases the ability of the blade to flex in the mid-portion because of the concave area below the thicker belly area of the blade.  Can you explain a little more, what that means, is that an element that adds to the knife withstanding the bends?

One more issue,. the curved edge and the more straight edge.  An edge that is recurved, how that would be different than a straight edge, does it make the cutting easier, give the blade an advantage?  Many people, especially in knives that have a chisel grind, or tanto tip, make the knives having a straight edge.  Does this offer a design disadvantage, compared to a fully curved edge?  Also in swords, daggers... 
David

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Larrin
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« Reply #9 on: October 05, 2007, 01:22:15 PM »

One interesting thing about L-6 is that it has no manganese, which is supposed to aid hardening. But, it is known to be easily hardened (as Larrin said) . It does have nickel for added toughness.
By the way, I don't know what information you have, or what L6 this is referring to, but L6 has plenty of manganese in it.
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radicat
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« Reply #10 on: October 05, 2007, 09:56:39 PM »

Larrin, you could very well be right about that. I thought I had read this about L-6 before somewhere. Maybe I'd read the same article before. The article by Joe Talmadge is the source, but I should check it out further.

Manganese
: An important element, manganese aids the grain structure, and contributes to hardenability. Also strength & wear resistance. Improves the steel (e.g., deoxidizes) during the steel's manufacturing (hot working and rolling). Present in most cutlery steel except for A-2, L-6, and CPM 420V.

http://www.zknives.com/knives/articles/knifesteelfaq.shtml

After checking some charts, I have to retract my statement and agree that the average manganese content is .25-.80% . The article is either a typing error or mistake. Thanks for catching that Larrin.      Clay
« Last Edit: October 05, 2007, 10:30:23 PM by radicat » Logged
Larrin
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« Reply #11 on: October 05, 2007, 10:23:58 PM »

That's strange because all of those steels have manganese. All steels do, at least .2-.3% of it. Sometimes manganese is not listed in the composition, but L6 most definitely has manganese, it has a good .7% percent of it, which is part of why it is so hardenable.
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radicat
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« Reply #12 on: October 05, 2007, 10:27:58 PM »

Thanks again, Larrin. See my edit on the above post.
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davidm
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« Reply #13 on: October 06, 2007, 06:23:26 AM »

I didn't want these questions to get lost because of the talk about manganese..

Thank you Ed and Clay,

The thing about the matrix your heat treating does, making it possible for the extreme bending.. it must be something I didn't even think,  that the matrix and banding extends throughout the hardened portion of the blade.  So, a similar 52100 knife made fully hardened with an edge of the same hardness, both knives having 60 hardness, while both knives may be similar in that way, the one with the more sophisticated heat treating will endure abuse and the other one will likely chip (because there is no matrix to support it).  Is that right? 

I remember years ago on the phone once you told me Ed, that the newer knives were on average better than your older knives because of the uniform consistency but that they would not compete with the best of your older knives.  This was about 7 years ago, and I don't remember what prompted the question about it.  Are there old knives, steel is nitrogen free, that have more advanced performance and compare to the new knives today, or do most (because of increased knowledge of what makes the best results) fall into a category you passed long ago regarding performance? 

For myself, I love the older knives.  Call it sentimental.. something about the art of the way you made them.  Just beautiful and they seem to define your style so well to me.  I did notice at Blade Shows 2000 and on, you kept carrying your old knife well beyond the time you were making newer, perhaps better performing knives?  .. so, you must feel that it served all the needs you would have. 

In newer knives, I do notice a lot of structural changes, edge geometry, thicker blades.. most of the older knives exhibit thicker blades.  The mod. Price grind, giving the knife the fullest design advantage. In testing did that dramatically increase the performance of your knives?

In regards to bending resistance, how have the newer knives of the video changed compared to the older knives made from bearing steel.  Rex made the point that because of the matrix and carbide banding the steel resists the bend, doesn't want to bend, and wants to return to straight.  On older knives was that same characteristic exhibited, or do you see an increase in resistance, or spring also?

The Modified Price grind, if I remember, I do remember hearing you say something about how it increases the ability of the blade to flex in the mid-portion because of the concave area below the thicker belly area of the blade.  Can you explain a little more, what that means, is that an element that adds to the knife withstanding the bends?

One more issue,. the curved edge and the more straight edge.  An edge that is recurved, how that would be different than a straight edge, does it make the cutting easier, give the blade an advantage?  Many people, especially in knives that have a chisel grind, or tanto tip, make the knives having a straight edge.  Does this offer a design disadvantage, compared to a fully curved edge?  Also in swords, daggers... 
David


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davidm
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« Reply #14 on: October 06, 2007, 06:44:20 AM »

Basic metal/forging question.

Does steel expand when heated or contract when it is cooling? .. is there stress, internal pressure when it cools, in the knife blade?  (In the first video Ed said the reason to anneal the bearing was it could explode if it was welded to the bar without heating it)  Does that mean knives when they are finished have some constant internal pressures at work?

The reduction in forging, is the density of the steel made greater, packing the material into a smaller area?  Or, is it only happening at a micro-level, where you really wouldn't notice it visually.
Thanks,
David
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