what does "takes a good edge" mean?

AmadeusM

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Ability to stay sharp a long time or simply the ability to take a sharp edge in the first place?

Does such a steel have to have high Carbon content? If so, how can cheap stainless blades in surgical scalpels be made to be so sharp?

Thanks.
 
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"Takes a good edge" means that you can get it very sharp. This does not require a high carbon content and does not mean that it holds that edge for a long time. There are hard stainless alloys that are very difficult to put a razor edge on. There are soft stainless alloys that are so inclined to form burrs that they are also hard to get to a razor edge. If your standards for sharpness are very high and that includes honing to very low angles you discover that not all alloys support your mania. There are alloys that make better scalpels than 440C. They aren't harder alloys, they are generally softer.
 
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to me "take a good edge" means the ability to get very sharp. To "keep a good edge" refers to the ability to stay sharp. All types on materials can take a good edge but to stay sharp with hard use is the tricky part. I would imagine that although scalpels have to be very sharp, they do not have to stay sharp for prolonged use
 
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Jeff Clark said:
"Takes a good edge" means that you can get it very sharp. This does not require a high carbon content and does not mean that it holds that edge for a long time. There are hard stainless alloys that are very difficult to put a razor edge on. There are soft stainless alloys that are so inclined to form burrs that they are also hard to get to a razor edge.

Great post, bears repeating. :)

Also, steels that have a lot of hard carbides are "grainy" and will not take as fine an edge as those with a rather simple alloy. Steels that form lots of carbides are usually better in the edge-holding department though.
 
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Usually, the thing that keeps a knife from "taking a good edge" is the thickness at the edge. You can put a good edge on almost any cutlery grade steel, if it's not too thick at the edge.
 
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Also has to do with the crystalline structure (molecular arrangement) of the steel. I don't know much about metallurgy, so I can't tell you completely accurately how it's done, but adding materials like carbon, chromium, vanadium, etc. affects the molecular structure of the steel. If the molecules are very close together with strong bonds, then you can put a sharper edge on the blade than a steel whose molecules are farther apart or more loosely bonded.

Cliff Stamp, cleanup in aisle 5...

Peace.
 
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Actually, I think it is a term with out much value.

You can take a bar of mild steel and sharpen it sharp enough to cut free hanging rope (Wayne Goddard wrote about that.) It will only cut once, but it will take an edge good enough to do that!

To me, when people say a knife takes a good edge, I hear it as a knife sharpens up OK given some standard sharpenign regimen. For example, 5 minutes on a stone and 40 strokes on a Sharpmaker and my 440-C knife took a good edge! But not my S30V knife though, it does not take a good edge (thats because it takes more than a few minutes on a stone and some sharpmaker strokes given the Vanadium and such!)

It may have some use I guess, as sometimes people ask about g-10 and other materials and their ability to take an edge. G-10 does not take a good edge. Titanium does, but does not hold it well unles you have a grade like beta titanium.

So I guess the term has some use, but very limited.
 
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Crayola, mild steel is a classic example of something that does "take a good edge". In fact I would use it as a reference point to illustrate how many stainless steels don't take a good edge. I grew up with simple carbon steels as the most common blade materials. I would guesstimate that these were commonly in the 1050 to 1085 alloy range. I took great pride in my ability to sharpen things. Then I hit my first hard stainless steel and found that it was many times harder to achieve the same edge. I branched out to a wider array of hones, a coarse hone for thinning edges and a straight razor hone for trying to refine the edges. Stainless is just a different beast. I started to strop using abrasive tapes as well as leather. It was virtually impossible to get an edge on stainless to compete with the edge that I could get with a simple carbon steel. For that matter the carbon steel was difficult to get as sharp as vanadium carbon steel. All this was after I had reprofiled the edges to similar acute angles.

Move forward to recent times. I really appreciate how sharp I can get AUS-8 or Sandvik 12C27 compared to the hastles with the 440 series alloys. I now have a ton of sharpening tools and can get extremely sharp edges on anything, but sometimes I have to strop on 100,000 grit diamond paste to get edges equivalent to sharpening 1084 on my old oilstone and stropping on my belt.
 
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I think that some steels definitely "take a sharp edge" better than others, or maybe I should say more consistantly than others.
And I don't think that it is all about the carbon content...my Atlantic Salt gets an extremely sharp edge rather easily and it only has about 0.15 carbon.

As for the surgical scalpels:
I routinely set in on operations (I'm a Radiologic Technologist) and the scalpels are not really that sharp IMO.
I've brought home a few over the years and most of my knives are just as sharp or even shaper.
Also, the scalpels are really only used to cut very soft tissue.
The surgeon typically has a variety of cutting instruments and, from what I've seen, the scalpel sees less use than the scissors during most surgeries--usually just used to make the initial incisions.

Allen.
 
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Crayola said:
Actually, I think it is a term with out much value.

You can take a bar of mild steel and sharpen it sharp enough to cut free hanging rope (Wayne Goddard wrote about that.) It will only cut once, but it will take an edge good enough to do that!

Due to their very low carbon content, mild steel alloys don't form a lot of carbides. That's why mild steel may even take a finer edge than high-tech cutlery steels. Just one example of why it is in fact a valid term.
 
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Jeff and Quiet Storm,

great posts! I think they help to claify my point. "Takes a good edge" I think has less to do with materials, and more to do with sharpening technique.

For example, take a dull 1095 blade and a dull 420V blade of identical shape, and start doing the "20 strokes per side" sharpening regimen. One could quickly form an opinion that the 1095 blade takes a good edge, and the 420V does not.

Of course there ar emeny variables I am leaving out, I only make my extreme point that the term is not that useful to help folks think about just how useful the term is.

I believe knowing how fine an edge a blade can take, how thin an edge can go while remaining strong or how logn an edge will last does more for a person than something like "it takes a good edge."
 
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Crayola said:
I only make my extreme point that the term is not that useful to help folks think about just how useful the term is.

I agree that it's less important than other aspects (toughness, edge-holding capabilities etc).
 
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Re: "I agree that it's less important than other aspects (toughness, edge-holding capabilities etc)."
I sort of hold the opposite opinion, getting sharp is the thing that defines a knife. Quite useful knives were made from obsidium and beaten copper which made incredibly brittle and soft blades respectively. Most knives are incredibly tougher than they need to be to accomplish everyday tasks. I find most of them do a really second rate job of cutting packing tape compared to a carbon steel utility knife blade. If you have optimally sharpened 1095 you will probably come to the conclusion that 440A is not a true cutlery alloy, just a stainless make-do.

PS. My opinions were highly influenced by Solingen carbon steel blades.
 
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I guess it also depends on one's personal opinion of what "sharp" means. To me a sharp knife needs to shave hair from my forearm, it doesn't necessarily have to be hair-splitting sharp.
 
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