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Best Steel Alloys & Chef's Knives for Holding a Low-Angle CONVEX Edge?

post #1 of 6
Thread Starter 

Today - very belatedly - I came across the Cooking Knives forum, which contains just the kind of information and opinion I've been trying to find for years. This is my first post.


Background: Decades of experience cooking, at one time for money (hired out as a "Rent-a-Chef", for 7 years, to pay for my higher education) but now for love (cook every day for 6 people, but sometimes up to 40, at various locations - to which I bring my knife roll, and, if necessary, my Sani-Tuff cutting board). Chef's knife and sharpening system fanatic, but the cost/benefit ratio rules.


Here's the Q:


Having tried Sabatier Elephant and some top-line German chef's knives, as well as a Global, I'm happiest with the stamped Forschner Fibrox (though a one-piece, stainless, made-in-China, 7 3/4" cleaver comes out when the going gets perilous for the Fibrox: the cleaver's soft steel is chip-resistant, and the edge hones as easily as it curls). Unhappily, I had to try nearly every home sharpening system - from carbide and ceramic V's; to stone and ceramic "wheelies";  to oil/water/diamond stones and rods, with and without angle guides; and including the last two generations of Chef's Choice electrics and manuals - before finding a system I could use to grind a good-as-new (maybe better than new) edge that would last a while. Ta-da: a 1" vertical, slack-belt sander and 4 belts - aluminum oxide at 40 micron (320 grit);  20 micron (500 grit); and 9 micron (1200 grit), as well as a leather stropping belt). I've had very satisfactory results with both Globals and Forschners simply by dipping my blades in cool water before each pass across the belts and keeping the bevel angle as narrow as I can without risk of scuffing the blade's sides, i.e., about 5* a side. I can feel the differences, in practice, among included angles of 20*, 15*, and 10* and prefer the 10* that I think I'm getting now.


BUT: The edges on my Forschners don't seem to last as long as the edges on my Globals. Since the two now have identical edge geometries (convex, about 10* included angle), and I've made allowances for differences in blade weights, geometries, and stiffness, the difference must lie in the alloys and how the steels are processed.


SO: Any recommendations for particular steels and particular chef's knives that lie near the of top the scale in edge-retention and near the bottom of the scale in cost? (Please remember: Whatever they are, I'm going to regrind them to my convex, 10* preference after they dull; I prefer the Fibrox's weight/balance, blade geometry, and handle shape/texture, though I'm open to experiment; and I care a lot more about function and cost/benefit than aesthetics.

post #2 of 6
It is my understanding that there are a few Artifex by Richmond with very interesting steels. Some users complain about relative thickness and, more generally, poor geometry. But that won't be your first concern.
post #3 of 6

The introductory parts of your post raise a lot of issues which seem bigger to me than the substance of your intended question. 


Just as a couple of examples: 

  • Forschners and most "top line" German knives are actually made from the same steel -- X50CrMoV15 -- and are hardened to similar levels, so whatever the difference you're experiencing it's not the "alloy;" and
  • Both Forschner and Global are far too soft to hold anything nearly as acute as a 10* included angle.


So, I think you're making some unjustified assumptions, and using them to make unjustified conclusions which -- in turn -- are acting as the threshold assumptions on which you're basing your question. 


Just about any edge you make with a slack belt grinder will be convex because the belt wraps around the blade as the blade is pushed into the belt, and as the blade sharpens.  In consequence, the actual edge angles aren't nearly as acute as the angle of the table (probably the explanation for your impossibly acute edge angles).  If you're going to continue to sharpen with the belt (and why shouldn't you?) and want advice, you should find a forum where there are at least a few people who sharpen in the same way. 


The alloys used by Global (Cromova 18) and Victorinox/Forschner are actually fairly similar in terms of performance if not formulation, and at their respective similar levels of hardness and similarly thin geometries their knives tend to roll and wave out of true far faster than they wear.  In other words, they typically ACT dull far more quickly than they TRULY dull.  If you give them regular and appropriate honing on an appropriate (extra-fine or smooth) hone you should get edge retention much better than most stronger/harder alloys and the Global/Victorinox edges should last longer before you need to go back to the belts. 


I'd talk to some other belt sharpeners before firing up the credit card.



post #4 of 6
I guess there is an error in the angle measurement. It should be measured from the axis of the symmetric blade, and not from the side.
post #5 of 6
Thread Starter 

My post was unclear about the sharpening method, and hence the "bevel" angle. 


At grave risk of inappropriateness on this forum (Is there a kitchen knife sharpening forum dedicated to belt sharpening?), let me try to explain: The grinding belt travels downward toward the table, and I sharpen with the direction of the belt, not against it - in effect, the knife edge moves away from the abrasive surface, not into it. Call it stropping rather than grinding. Since (a) the table isn't designed for stropping; and (b) I'm unable to find or make an adjustable angle guide for stropping that works for kitchen knives; and (c) I don't have the skill to re-wire the sander so the belt moves upwards rather than downwards, I sharpen freehand, with the knife edge facing down toward the table and pressed lightly against a section of the belt that has no backing plate, so the belt is slack. All I can say is that I've been able to achieve better - and much faster - results, on various kitchen knifes, with this method than with all the others I've tried.


While moving the edge across the downward-running belt, I estimate the "bevel" angle by sighting down from spine to edge, and laying off a bit for spine/blade thickness (calls for close attention to spine taper), as well as a bit for belt flexion. 


SO: I estimate the "bevel" angle from the side of the blade to the point at which the edge contacts the belt. Easier done than said, but there's a baseline for estimating: anything more acute than 5* tends to scuff the side of the blade.


About the "bevel" angle of a convex edge: If you draw a (very narrow, symmetrical) gothic arch with a straight line across the bottom connecting the two sides of the arch, and then draw a straight line within the arch, from the apex to the bottom of one side, and then measure the angle of that line to the connecting line, the "bevel" angle equals that angle subtracted from 90*.


Sorry for the prolixity.


Still, does anyone have thoughts about alloys and/or chef's knives that they've found to be notably resistant to edge curling/rolling, regardless of "bevel" angle? Maybe there aren't any meaningful differences.

post #6 of 6
Thread Starter 

Don't think there's a conceptual error - "bevel" angle is estimated based on an imaginary straight line from the beginning of the edge's "bevel" to the cutting edge - but there's certainly no precise measurement.

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