Sharpening - # of strokes a function of steel hardness?

Z

zombywoof

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Oct 8, 2012
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Say you have a guided sharpening setup (DMT, Lansky, Spyderco) with a range of stones from coarse to very fine.

All else being equal, a knife with harder steel will require more strokes with each given stone than a blade with softer steel to achieve the same results, no?

If so, if considering blades on the edges of the "soft"-"hard" spectrum of typical production knives are you talking 2X as many? 5X? 10X? ??

Thanks.
 
The type of steel would also be a factor. I don't think that S30V is a lot harder than other steels, but it takes several times as many strokes on the EP as other steels. I don't count strokes, so I can't tell you how many more it takes, but it is at least 3x my other knives.

Allen
 
Sort of. Abrasion resistance is of more concern than pure RC hardness when you start getting into grinding on it. In general, higher abrasion resistance steels will be harder, but not necessarily. 3V, for instance, is a LOT more resistant than A2, even in the same 58-60 hrc regime. It takes considerably more effort to sharpen, and holds its edge correspondingly longer.

There's a LOT of things that go into how a steel sharpens. :)
 
Steel hardness & abrasion resistance (abundant carbides vs. a lack of them) will be a big factor, and will make a big difference in how fast or slow the work goes. So many other variables, though, such as pressure of hone against the steel, speed of the stroke (fast vs. slower), abrasive type & grit size, size and condition of the hones used, lubrication (oil, water, etc.). The type & degree of sharpening will also be a big variable, depending on whether you're just touching up an already decent bevel, or completely creating a new one (much more metal removed). It's impossible to predict how many strokes it'll take. The better path is to pay close attention to the edge as you work. Frequently inspect it with a magnifier & bright light, and watch for the burr formation.

The point above, about the pressure used and speed of the stroke, is so variable, even if all other factors remain exactly the same. In sharpening my own knives, I've noticed how difficult it is to even attempt to maintain the same pressure & pace from stroke to stroke, especially if the work is taking some time. Fatigue starts to creep in, focus starts to drift a little, and the speed and/or quality of the work always changes as a result. This is further compounded by the gradual loading of the hone with swarf, which will slow it down as work continues. For me, it's a natural temptation to 'press harder' if the work seems to be going slowly, though I do my best to resist. ;)
 
Abrasion resistance is of more concern than pure RC hardness when you start getting into grinding on it.
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Yes. It's the abrasion resistance which determines the ease of grinding not the load resistance which is itself determined by the hardness. It's the matrix hardness which is measured on the Rockwell scale, not the one of the carbides which determine, by their amount and types the abrasion resistance.

A soft alloyed steel may be harder to grind than a carbon steel pushed to a high hardness.



There's a LOT of things that go into how a steel sharpens. :)
Click to expand...

By instance the amount of coffee drunk before.


dantzk.
 
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