Jeff :
Most low-chromium steels like 1084 or 1095 are relatively homogenous, fine-grained, and easy to abrade with a hone. They take a true razor edge easily. They also respond very well to a leather strop for an easy scary sharp edge.
I had made the same correlation myself about stropping, until I started working with an ATS-34 blade with an 8-10 degree edge angle which responded to a strop very well. At first I though it was simply aligning easier because the more acute edge would be more readily deformed, however after checking the edge under magnification I think it could be because all the carbides have been broken out from the edge. I should run a few trials on edge holding with this blade at 8-10 degrees per side and then at a micro-beveled 15-20 degrees per side. If the carbides have broken out then the edge retention should probably be significantly effected, then again there might be a large gain just from the higher angle. I'll have to check that independently. What you said though makes perfect sense, a simple steel should be much more readily stropped, however hardness, edge profile, and buffing compound used are all critical factors.
If you like really sharp edges ...
One of the biggest problems in such discussions is that the terms being used don't have standard definations. For example in wood working, sharp just means polished, so the sharpest edge is the one that can take the highest finish, therefore you want the finest grain, which is something like 52100. However for slicing, such edges are far from optimal because they go comletely smooth at a high polish and thus just skid along harder materials like poly rope and such. From such a perspective you want an edge that has a coarse grain and large segregrated carbides (dendritic steel). However you can achieve better slicing performance in a fine grained steel with a coarse grit finish than the most agressive steel at an ultra fine finish. So an interesting question would be which edge is more durable, a fine grained steel with a rough finish, or an aggressive steel at a fine finish, both at the same level of slicing ability. You don't need to get very rough grit wise, to equal the aggression of an inherently more agressive steel, Carbon V (or even 52100) for example is
much more aggressive at 600 grit DMT than D2 is at a fine ceramic finish. D2 is more aggressive when both are at equal finishes.
matthew rapaport :
I have an ATS-34 blade which I can make easily sharp enough to shave me with a simple strop and some jewlers rouge... Secret? It is only 1/16" thick!
The blade stock has little or no influence on the ease of sharpening, the critical factors geometry wise are the edge angle and width, both you want minimized and are critical in influencing the cutting ability and ease of metal removal. One other factor to consider, is that sharpening is a very precise activity, while some people can do it with the same amount of difficulty as walking (see Fowlers video for example) , it doesn't take much for it to get totally mangled. Don't write a steel off just because it refuses to get sharpened, there are some days when I can't do much of anything on knives that on other days just takes a minute to perfect the edge. Can't get rid of a burr is the usual problem, too much pressure and it reforms, too little pressure and you don't abrade it, just flip it over.
There is also a whole other level of sharpness that I have never been able to duplicate but have seen on a couple of blades. For reference, most of the "shaving sharp" production blades score about 100-125 g on the thread cutting. This is that sharp that the hairs are removed with just a minimal of force touching them, "hair popping sharp", push cut paper etc. . However I have seen the odd blade score about 30-50 on the thread, this is so sharp that you can barely touch the thread and it is cut. This is the same level of sharpness as a razor blade, I tested a bunch of them awhile back. I can get a blade to cut the thread this well if I bring the angle down to about ~8 degrees per side, but I have seen it on blades with angles as high as 17 degrees per side, last one was on a Gransfors Bruks Axe. This isn't a "wire edge" either because it doesn't break off readily. I would like to know how they are getting this level of sharpness.
I'd be willing to bet that given knives with an identical edge geometry, sharpened all to an equal initial edge by what ever method one chooses, no human could distinguish between one steel or another by simply feeling the edge.
I have determined sharpness differences by as little as 5-10% (thread and 1/4" poly), by a simple shaving test. The human body is capable of determining very small changes in forces, just a very percent. Anyone who does a lot of work with their hands will develop this sensitivity to a very high degree.
B . Buxton :
I compared 6 knives against there ability to razor sharpen and cut, and this is what I came up with.
Interesting results. What were the hardness of the blades? Have you done any such cutting with a high alloy blade like D2 at ~60 RC? Do the blades respond any differently to steeling after they have been blunted? Does the relative performance change if you run them after steeling but not honing?
-Cliff
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