Diamond plates are not recommended on all steels with lower than 58 HRC because of one simple reason

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matto6

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Wisdom? Or Nonsense?

From this TSPROF video on choosing abrasive stones for sharpening: (420 seconds in)

Many people wrongly believe you only need diamond stones, but it's not like that
Diamond plates are not recommended on all steels with lower than 58 HRC because of one simple reason
Due to its viscosity, the steel tears the diamond stones out of the bundle, the plate wears off and stops working.
You will damage your plates
For this reason, for steel lower than 60 HRC, I'd recommend using synthetic stones.
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I have a set of the double sided Venev disamond stones.

I also have a set of these tsprof silicone carbide stones. I was going to sell them with the TSPROF sharpener I'm selling, but based on that video maybe I'll keep them for softer steels.
 
From what I've come understand while reading threads here on BF, diamond tear out seems to occur when too much force is applied to the stone when sharpening. The high pressure from the force bearing down on the stone combined with moving the steel along the stone results in tear out. If your pressure is not severe, this wear issue seems to be not an issue.
 
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matto6 said:
What about softer kitchen knives? Henkle, etc.
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Kitchen knives, too, including the cheapos my wife prefers:confused:. We have a few Henckels, probably 35+ years old now, still work perfectly, as well as various other makes, I would guess all around 57 HRC or so.
 
I've used diamonds on everything for many years with no problems . Most probably under the 58 mark .

But I do use a light touch . :)
 
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I can't say I've done the supporting scientific testing to back up these theories, but I will go ahead and share them anyway. 1 I think was mentioned above, the diamonds will gouge deeper into softer steels, making diamond tear out on the plate more likely. 2, the diamonds gouging deeper into the soft steel will leave a less desirable edge, more ragged and fatigued.
 
Diamonds are a knife afi's best friend.
 
Baron Mind said:
I can't say I've done the supporting scientific testing to back up these theories, but I will go ahead and share them anyway. 1 I think was mentioned above, the diamonds will gouge deeper into softer steels, making diamond tear out on the plate more likely. 2, the diamonds gouging deeper into the soft steel will leave a less desirable edge, more ragged and fatigued.
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I must be doing it wrong then, since diamonds give me a hair shaving edge on all steels, including the ones I make knives from, which are mostly low alloy simple steels (1084, 15n20, 8670, AEB-L, LC200N).
 
Diamonds work fine with my Henckels. The softest knives I have that diamonds work with are some 35 year old Chicago Cutlery. I don't think diamonds are the best for the CC knives but they do work. But since I never use them it's not much of an issue.

If you keep the pressure light enough you won't damage your diamond stones, even with gooey soft steels that diamonds just make a mess of.
 
Again, I have not seen the data to prove these concepts, but I will say, if correct, it would still be possible to achieve high levels of sharpness on softer steels using diamond plates, especially if finished on a high grit bonded stone or strop. Even still, you would see a reduction in wear resistance and edge stability from the damage done by the deep gouging at the apex. The light pressure, finer stone, or strop used to finish the edge would realign the edge into a keen geometry, but the steel would be weakened compared to an edge fully formed by appropriate abrasives.
 
This is just my logic, but the only reason that tear out would happen is too much force/pressure in the sharpening stroke, and for softer steels there is less reason to use too much pressure in the first place. I suspect the reason for reduced performance of diamond plate after sharpening softer steels is more likely to be from loading and not cleaning the plate after use.
 
Pretty sure the reason diamonds would get ripped out is from high pressure. Don't lean into coated abrasives. The same thing happens with very paper-backed sandpapers if you bear down too hard on a piece of wood. Let the abrasive do the work and it's fine. If you want pressure, use bonded abrasives.
 
Those theories dont mean squat to those of us that KNOW how to sharpen a knife. Too much force being applied. Ptooey!
Not only that, they are misguiding those who are learning by giving biased info.
 
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I'm convinced this issue is due to any one or any combination of at least three possible causes, none of which have anything to do with the softness of the steel being sharpened:

1 - Too much pressure used.
2 - Poorly manufactured hones (junk).
3 - Not using adequate lubrication on the hones.

I optionally use diamond hones from DMT or EZE-Lap (read: decent quality) on blades in the HRC 55-57 hardness range. Knives from Case (their stainless blades) and Victorinox (HRC 56), to name a couple. I've yet to see any issues of the hones being damaged by such use on these 'soft' steels.

I think the vast majority of the problems come from using too-heavy pressure on diamond hones, NO MATTER THE STEEL TYPE. In fact, I could more likely see that harder and more carbide-heavy steels would be capable of doing even more damage to the nickel plating on such hones, if pressure used is too heavy.

Other issues like clogging can become a problem with some 'soft' stainless steels. The steel is cut from the blade in tinsel-like ribbons and can cover & cling tenaciously to a plated hone's surface, bringing cutting/grinding to a halt. This is where the use of adequate lubrication makes the most difference, as it minimizes the ability of the swarf to cling and allows the surface of the hone to be easily wiped clean of swarf.

Acquiring the feel for pressure used on a diamond hone takes some time and readjustment, if one is used to sharpening with other stone types. My thumbrule for use of pressure on such hones is basically to reduce pressure by at least 2/3rds of that used with any other stone. Putting it another way: diamond is roughly 3X as hard as the synthetic abrasives (AlOx or SiC) used in any other stones. This means it cuts just as deep at about 1/3rd the pressure. Anything heavier than that will just force the blade steel down into the nickel substrate and create other issues, like hone damage or heavy burring, rolling or chipping of the edge.

I'd say that the softer steels I sharpen on diamond hones present LESS of a risk for damaging the hones. It's all about the pressure used and lubrication, which can render these issues essentially moot.
 
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matto6 said:
Wisdom? Or Nonsense?

From this TSPROF video on choosing abrasive stones for sharpening: (420 seconds in)
Click to expand...
no nonsense!

it's definitely true for the diamond:poop: stones which he is using in his video. i have these stones too, they're made in the china and all things considered are not bad. just doht use them on softer steels on guided systems like Ruixin Hapstone KXProf
 
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