Which stones remove more metal?

S

SS234

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Jul 18, 2020
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I get the impression here that Diamonds remove the most metal. With good reason. Nothing is harder than Diamonds. However many sharpener manufacturers would like us to think that Tungsten Carbide does. In my travels I have found that they are in fact correct. This would seem scientifically impossible. Why might it seem and they would like us to think Tungsten Carbide is harder? You would think to a blade full of Tungsten it would not even cut it at all. I am well aware that most of you would not touch Tungsten Carbide stones with a 20 foot pole. Why is that? Thank you
 
I'd say it depends on the grit/coarseness of the honing material.

I've been using diamond hones for almost 2 decades, and I don't see any noticeable loss of steel on my knives. But then I use fine grit for touching up the edge, not extra-coarse.

And then there's the person doing the sharpening. If someone is really grinding down on their hone, or doesn't have a good sharpening technique (or simply doesn't know how to sharpen), then they might end up removing an excessive amount of steel.
 
How fast metal is removed is dependent on many things:

1 - HARDNESS of the grit, as compared to the hardness of the metal being ground upon.

2 - SHAPE of the abrasive grit doing the grinding - more angular, 'sharper' shapes will cut more aggressively than blockier or rounder shapes.

3 - SIZE of the grit doing the work - in simplest terms, a larger grain of hard, sharp grit will cut a deeper and wider trough into the metal being cut.

4 - TOUGHNESS of the grit doing the work - this refers to its resistance to breaking or fracturing as it's working.

5 - WEAR RESISTANCE of the grit, which refers mainly to the ability to maintain its shape without dulling by abrasion.

6 - FRIABILITY of the grit, which is the tendency of individual grit grains to break down or fracture into smaller grains.

7 - LUBRICATION of the grit, which helps prevent clogging or accumulation of metal swarf as the work is being done. Also helps with cooling of the grit in powered grinding applications generating a lot of heat. With regard to heat, some abrasives are more stable and harder/longer-working at high temperatures than others will be.

8 - How the abrasive is bound or held together - the 'binder' for the grit can be designed to hold it firmly, as with a plated diamond hone, or to release worn grit more easily from the surface and expose fresh, sharp grit to keep the stone working aggressively (think of water stones in particular, and oil stones secondarily). With a plated diamond hone, the toughness and wear-resistance of the plating itself is a big factor in determining how well it holds onto the embedded grit. And the bond itself, between the grit and the plating, can vary in strength as well, which influences how long the plated hone will last and retain the grit.

In terms of hardness, the abrasive only needs to be somewhat harder than the material being cut. Extra hardness just allows the work to be done with a lighter touch to cut to a given depth (assuming other factors are equal, like size, shape, etc.). Anyone who's ever accidentally left some deep, ugly scratches on a blade with a featherlight, errant brush against a diamond hone will immediately understand this concept.

Friability is often designed deliberately to advantage with some abrasives (like aluminum oxide especially, and with silicon carbide to a narrower degree), allowing the grains to break down into smaller, but still sharp & jagged, cutting edges. Silicon carbide is inherently more brittle or friable in general - but some engineering tweaks can also make it a little less so, as desired, according to usage.

Between friability and the binders used, these are both factors influencing how a stone can be kept working without 'glazing' (dulling/polishing of the surface) or otherwise being worn out.
 
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SS234 said:
I found something even harder. Boron Carbide. 30x harder than diamond.
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Its Vickers hardness (38 GPa), Elastic Modulus (460 GPa) and fracture toughness (3.5 MPa·m1/2) approach the corresponding values for diamond (1150 GPa and 5.3 MPa·m1/2). As of 2015, boron carbide is the third hardest substance known, after diamond and cubic boron nitride, earning it the nickname "black diamond".
Click to expand...

Source: Wikipedia
 
My bad. Misinformation from some page. You know I had that other post I blew off. I have this Diamond wheel sharpener I got yesterday. It either rolls or chips the edge on anything. i don't get it. What the heck could be going wrong with it? How could Diamonds dull a knife? If anyone wants to look at the other thread please. I really wanted that to work. There is no reason it should not. I have no clue. Any help appreciated. Thanks.
 
Spideyjg said:
Tungsten Carbide is usually in a pull through "sharpener" and the TC edge will shave steel off the blade. They will jack up a blade in a blink.
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One exception is the single-sided type where it's just a little piece of tungsten carbide brazed to a handle. Those are handy for removing wire edges and cutting off stubborn burrs, and work well as an alignment tool like a butcher's steel. I consider them a handy tool in the arsenal. But yeah--drag through sharpeners are almost universally trash.
 
I had just got a drag through that looked to be very promising. Boy was I wrong. Duh!

FYI, There are actually very small TC stones. Well, like a little fully open square on a plastic handle. They are hard to find that is why they are seldom mentioned. However SIC is much better but way more money. The TC will still put an edge on. It just takes longer than the SIC. For some reason I prefer the way either Carbide behaves (only) for putting on an edge. For just sharpening a knife I don't even use stones. I use rods, and yes they are Diamond. In various grits. If I want to go scary sharp I finish buffing with Flitz at low RPM. I also wanted to mention Ceramics and Aluminum Oxide have their place in my arsenal as well. I will use anything proven at my disposal. Pull through of course is not.
 
My 80 grit Silicon Carbide Ace Hardware stone removes metal fast. They are hard to find now. DM
 
MtnHawk1 said:
I have an extra extra coarse diamond plate and the 60 grit Manticore is much faster.
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Manticore is fast. 140 Atoma is pretty fast. Coarse side of the Foss combination stone is fast. The diamonds are slower but not by a huge amount.
 
Obsessed with Edges said:
How fast metal is removed is dependent on many things:

1 - HARDNESS of the grit, as compared to the hardness of the metal being ground upon.

2 - SHAPE of the abrasive grit doing the grinding - more angular, 'sharper' shapes will cut more aggressively than blockier or rounder shapes.

3 - SIZE of the grit doing the work - in simplest terms, a larger grain of hard, sharp grit will cut a deeper and wider trough into the metal being cut.

4 - TOUGHNESS of the grit doing the work - this refers to it's resistance to breaking or fracturing as it's working.

5 - WEAR RESISTANCE of the grit, which refers mainly to it's ability to maintain it's shape without dulling by abrasion.

6 - FRIABILITY of the grit, which is the tendency of individual grit grains to break down or fracture into smaller grains.

7 - LUBRICATION of the grit, which helps prevent clogging or accumulation of metal swarf as the work is being done. Also helps with cooling of the grit in powered grinding applications generating a lot of heat. With regard to heat, some abrasives are more stable and harder/longer-working at high temperatures than others will be.

8 - How the abrasive is bound or held together - the 'binder' for the grit can be designed to hold it firmly, as with a plated diamond hone, or to release worn grit more easily from the surface and expose fresh, sharp grit to keep the stone working aggressively (think of water stones in particular, and oil stones secondarily). With a plated diamond hone, the toughness and wear-resistance of the plating itself is a big factor in determining how well it holds onto the embedded grit. And the bond itself, between the grit and the plating, can vary in strength as well, which influences how long the plated hone will last and retain the grit.

In terms of hardness, the abrasive only needs to be somewhat harder than the material being cut. Extra hardness just allows the work to be done with a lighter touch to cut to a given depth (assuming other factors are equal, like size, shape, etc.). Anyone who's ever accidentally left some deep, ugly scratches on a blade with a featherlight, errant brush against a diamond hone will immediately understand this concept.

Friability is often designed deliberately to advantage with some abrasives (like aluminum oxide especially, and with silicon carbide to a narrower degree), allowing the grains to break down into smaller, but still sharp & jagged, cutting edges. Silicon carbide is inherently more brittle or friable in general - but some engineering tweaks can also make it a little less so, as desired, according to usage.

Between friability and the binders used, these are both factors influencing how a stone can be kept working without 'glazing' (dulling/polishing of the surface) or otherwise being worn out.
Click to expand...

Great post. :thumbsup:
 
HeavyHanded said:
Manticore is fast. 140 Atoma is pretty fast. Coarse side of the Foss combination stone is fast. The diamonds are slower but not by a huge amount.
Click to expand...

I like and use my Atoma 140 and XXC DMT but not for hogging off metal as quickly as I can freehand. When I first bought a ~120 grit diamond several years ago I was disappointed it didn't remove metal faster, even though I used more pressure than I should have, or would use now, since all diamond instructions I have read say to use light pressure. I've tried a few different abrasives around 120 grit, and lower, for quickly removing metal, including an 80 grit diamond and emery cloth as low as 50 grit. None of them worked nearly as well as the 60 grit Manticore. That worked so well I stopped experimenting.

Besides lower grit size, of course, I (as well as others here) found heavier sharpening pressure for quickly removing metal to be very important, just as light pressure is important in the finishing stages.

I'm just reporting what my results were with informal experimentation, done out of curiosity. As is said, YMMV.
 
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