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Author Topic: Questions about practice and procedures  (Read 13320 times)
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davidm
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« Reply #30 on: October 15, 2007, 04:01:31 PM »

Ed,
I want to make sure i understand a point..  Two knives, both being made in 52100.  One having a more advanced, differential heat treating, and the other being just simply fully hardened.  Both knives, being the same in grind/sharpness and edge Rockwell value.  Grain refinement on one (14 and finer), and 6-7 on the other?

Would there be a difference in the hemp rope cutting test on these two knives? 

I'm wondering if the hardened area, (differentially heat treated blade) being able to take the 180 bends gives it other resistance to edge degrading or is it more stricly an advantage of taking more abuse, what it can withstand in flex.   
David

*I do remember the tests in Knife Talk 1, showing the results of cutting on hemp rope.. the triple quenched blades outcut the single quenched.  I do not know what were the reasons, how the edge was improved?
« Last Edit: October 15, 2007, 04:12:56 PM by David Mullikin » Logged
Ed Fowler
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« Reply #31 on: October 16, 2007, 01:03:38 AM »

Two knives forged and worked up my way:
single quench fully hardened blade would not cut as well as a triple quench fully hardened.

The fully hardened blade would fail in one event maybe 3 - 180 flexes, maybe more, maybe less.

The differentially hardened blade will hang in there, even after the edge cracks, you still have a usable knife.

Which is stronger? I have not put a torque wrench on a fully hardened blade, but you cannot bend a pronghorn blade in you hands, so I believe they are plenty strong enough.

Remember the Jerry Shipman event when he had to cut his way out of a semi sleeper? His single quench 52100 blade snapped like a piece of glass. He was just lucky to have a Bill Burke blade that was worked up right.

Another reason I don't like fully hardened blades is that they will chip when hit with a hard object, like a rock or hammer. A fragment of steel flying around is a serious hazzard. I once nearly lost an eye due to a hammer head that chiped and stuck the chip in my eyelid.

This may not sound like a great advantage to have, but those who have experienced a serious wreck well know what I am talking about. When betting the ranch you want all the odds in your favor, these little things I mention can be a big deal

I hope this has answered soem of yoru quesitons.
Thanks for asking
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davidm
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« Reply #32 on: October 16, 2007, 12:16:25 PM »

Yes, thank you Ed!

Just to be sure I understand.. Grain refinement, does it play a role in the endurance of the cutting edge?

I've never understood if there is a coorelation between the grain refinement and cutting endurance, just that it gives the knife blade the ability to withstand the abusive situations, makes it tougher.  Which is a huge advantage, over a fully hardened blade, I understand.   

This may be a metalurgy question for Rex, just what is happening to make the triple quenched blades outlast the others on hemp rope, if they are made the same in hardness?  Do they wear differently?
David
« Last Edit: October 16, 2007, 12:18:05 PM by David Mullikin » Logged
Ed Fowler
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« Reply #33 on: October 16, 2007, 03:23:19 PM »

The difference between highly refined grain and coarse grain is similar to the difference between one of those rap deals and a Bethoven symphony. Grain refinement is what makes blades cut in the high performance level and still be easy to sharpen and tough enough to stand up to hard work.

This is why we test for tough (edge flex) before we test for cut. If a blade is not tough, you cannot depend on it in the long run.
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davidm
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« Reply #34 on: October 16, 2007, 04:47:31 PM »

Thank you Ed, I appreciate it.  Sorry, I get to rambling on with questions..

We are playing a symphony this week, Gustav Malher's 5th.  It lasts 70 minutes and has a very complex structure.  Your reference to a symphony makes a good parallel, the transition zones, the inner "music" of what you create.  Not everyone would be able to appreciate it.  I have students who can't listen to 5 minutes of a symphony, they have no patience or conditioning to even begin to understand what it means, in a most basic way.  But, for those who do, and can take the time to try to understand it, it makes sense, and can be appreciated.   

I am honored to have the opportunity to ask you about these things, some of it I may never understand, but I do see the big picture, I hope.  And, it is good.   

How is the weather out there in Wyoming?  It has been very dry here in NC., maybe nothing like the high desert.
David
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Alan
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« Reply #35 on: October 28, 2007, 12:42:38 PM »

I've been curious about what Wayne Goddard is doing with the new friction process
I was watching the NASA TV ch and saw how the guys designing the new moon space ships are welded them up with the friction weld system.

It's the wave of the future guys.
From the way they have learned how to weld with friction , nothing can come close to what it can do.
The welds were close to seamless, the welds were stronger, and airtight.

The big deal with the friction weld system is that you can get a hot weld right next to cold steel, and this means that you do not weaken the metal next to the weld as happens with other welding.

To a knife maker this is worth thinking about.  This ability to harden the  steel knife edge to it's limit without harming the rest of the knife blade at all.
I have not heard of anyone useing 52100 steel yet for a Friction  Welder, (The Friction welder tool is a High $) but I bet down the line in the future someone will give it a go.

Who knows what a guy might be able to do?
Perhaps blade hardness in the Rockwell high 60s?
70s?
 with no danger of cracking at all.
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davidm
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« Reply #36 on: October 29, 2007, 01:15:59 PM »

There is also something new where two steels can be fused together, something to achieve a hard edge/soft back.  The Kershaw knife of the year "Tyrade" has it, but I haven't heard any talk about this at all.   The friction forging seems to be where all the hype is at the moment.
David
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Ed Fowler
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« Reply #37 on: October 29, 2007, 03:11:15 PM »

In my time in the world of knives, I have seen many new and improved products that were predicted to take over the world of knives by storm. Last night I was looking at knives made in the good old USA for the past 300 years. That is the longivity of the honest forged blade, she has and will survive. I might note that the chipped stone blade also survives.
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