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TOPIC: Interesting video... do you destress your edge?

Interesting video... do you destress your edge? 6 months 3 weeks ago #15815

  • leomitch
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Once again Cliff your deep knowledge of steels is much appreciated. My favourite steels for super easy and super sharp edges is Sandvik 12C27 and 13C27. My French folders from Chambriard use the 13C27 razor steel and the edges obtainable with little sweat on those blades are most satisfying. My Helle Temagami knife uses a triple laminate steel with 12C27 at the apex point. Love these very sharp knives.
Once again thanks for the stimulating comments.

Cheers
Leo
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Gibbs rule number 9

Leo James Mitchell
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Interesting video... do you destress your edge? 6 months 3 weeks ago #15817

  • CliffStamp
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I generally recommend anyone who wants to learn/understanding sharpening get at least one steel which is easy to sharpen simply to see what should be the ideal process. Everything you have listed are examples of that as they are all razor blade steels and when hardened properly they are ideal as they have :

-excellent grindability
-trivial ease of sharpening

In general there is rarely even an issue with burr formation/removal. While difficult to obtain, if you really want to see something special try to find :

-AEB-L at 62/64 HRC
-1095 at 65/67 HRC
-SuperBlue at 65/67 HRC
-M2 at 64/65 HRC

These steels are so strong that the edge will form very crisp very easily. However the HT is critical and if it isn't done well then you will likely hate it.

I have a knife from Joe Calton in full hard 1095 which I expect to perform well from a very quick inspection of it. Even with the edge set on a semi-coarse Norton diamond :

-it shaves with no pressure felt on the skin
-true/90 push cuts newsprint at 3/4" from the point of hold

As boxed it is one of the sharpest knives I have seen in a long time.
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Interesting video... do you destress your edge? 6 months 3 weeks ago #15818

  • leomitch
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I have an ESEE Laser Strike knife of 1095 steel but I don't know the hardness. I do know it sharpens up beautifully but with more effort necessary than for either of the Sandvik steels. Do you know the ESEE knives at all...they are all 1095 carbon steel.

Leo
Never go anywhere without your knife!
Gibbs rule number 9

Leo James Mitchell
Last Edit: 6 months 3 weeks ago by leomitch.
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Interesting video... do you destress your edge? 6 months 3 weeks ago #15819

  • CliffStamp
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Yes, I have a number of them.

They set the hardness at 55-57 HRC so while the steel will grind easily, there are likely to be some issues with edge crispness / burr formation if you are trying to achieve a very high sharpness.

Of course they are promoted for very heavy use and thus the tempering is going to be high, above 450 F to ensure they are outside of the embrittlement range and thus the mid-range hardness.

They are quite durable though and resist fracture strongly.
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Interesting video... do you destress your edge? 6 months 3 weeks ago #15820

  • leomitch
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Thanks very much Cliff! That is exactly what I wanted to know. You are a genuine huge nugget of knowledge that all of us are going to appreciate. I suspect we will be wanting information on steels like this in our Wiki and we will be getting to that fairly soon I hope. Your encyclopedic knowledge will be useful here.

Very best regards
Leo
Never go anywhere without your knife!
Gibbs rule number 9

Leo James Mitchell
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Interesting video... do you destress your edge? 6 months 3 weeks ago #15821

  • wickededge
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Cliff,

Thanks for jumping on to the conversation and adding your knowledge. I'm really glad you did.

--Clay
--Clay Allison
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Interesting video... do you destress your edge? 6 months 3 weeks ago #15826

  • TarasShevchenko
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CliffStamp wrote:
-AEB-L at 62/64 HRC
-1095 at 65/67 HRC
-SuperBlue at 65/67 HRC
-M2 at 64/65 HRC
for the hardness numbers to be as high as this, these steels should be almost untempered, this is very close to "as quenched" hardness figures for given types of steels. Will it be useful for anything more than paper cutting, wouldn't it be too brittle?
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Interesting video... do you destress your edge? 6 months 3 weeks ago #15827

  • CliffStamp
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I have knives in all of those steels and more, the 1095 is actually above the as-quenched hardness due to the strong carbide precipitation it has due to the super saturation of martensite.

In general no, they are not so limited - but again, they have to be done right. Here is just one example of a 1095 paring knife being used in non-paring knife work :



and why not :



and :


The paring knife is ground from 1095 high carbon steel hardened to 66 HRC. The blade is 0.055" thick, 0.41" wide, 2.8" long and weighs 35 g. The edge is 0.010-0.012" thick, ground at 5.7 +/- 0.4 degrees. At 0.2" back from the edge the knife is 0.021" thick. There is a full distal taper to point.

It has a micro-bevel normally, 10-12 dps, usually a very high finishing grit (high for me), which is 4k+ waterstone or similar.

Again though, and I can't stress this enough - if the HT isn't there the steel will be horrible as there are many ways to get hardness but only one right way :

-presoak
-soak at the minimum time/temperature to put 0.6% carbon in solution (CRITICAL)
-quench immediately
-cryo immediately
-snap temper
-water quench

repeat cryo until cost is a factor, water quench after the snap temper, then final temper around 350 F give or take (M2 is a HSS so it tempers hot).

The first part is critical, if you soak too long more than 0.6% carbon goes into solution, plate martensite forms instead of lathe, the steel becomes very brittle, it becomes hard to remove retained austenite, etc. .
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Interesting video... do you destress your edge? 6 months 3 weeks ago #15831

  • CliffStamp
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This is an example of a full hard 1095 blade :



This is Calton's paring knife :

-0.055" stock
-ffg (hint of convex, you can't see it but you can mic it)
-edge is micro-bevel only, not visible
-norton diamond, worn/fine

Here is a really horrible picture which I used to think were ok before I started looking at Clay's pictures :



The scope I am using has a horrible issues with depth of field and reflection hence coarse edges look very blobby, but in any case you can see the very small bevel, this is at 50X linear magnification.



Here is the edge after sixty 2" slices on that rope, note no chips/rolls, just light wear. The initial performance was :

-6 to 7 lbs

after 60 cuts it was in the plateau and was :

-11 to 12 lbs

If those numbers don't impress you, just try to cut a piece of 3/8" hemp with a 2" draw with less than 6 lbs of vertical force.

In any case, this rope is fairly demanding on edges, more so than most kitchen use anyway and similar to cardboard and other utility work and it does nothing significant to the edge.

The edge only reflects light in one small section of edge which was the peak force position during the slices.
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Interesting video... do you destress your edge? 6 months 3 weeks ago #15835

  • LeoBarr
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It looks deadly sharp the thinness of the taper to the edge is what makes the knife practically sharp high levels of polishing does not necessarily make a sharp knife especially if there are appreciable shoulders on the edge of the final bevel .
I alway s think that big shoulders are like air brakes on a wing the leading edge if fine for cutting processed foods like thin sliced ham or cheese but if the blade it to really cut it needs to have no real shoulders then the knife will cut deep which is what is needed for preparing real food.

That paring knife looks and sounds awesome!
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