Diamonds No Good For Steel?

ejames13

ejames13

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I'm curious to know what some of the sharpening gurus have to say about this. I was watching this video of the Edge Pro inventor, and he's saying diamonds shouldn't be used to sharpen any kind of steel because they will sink into the steel and end up being ripped off the surface of the stone. What say you?

The discussion I'm referring to starts at 10:13 in the video.

 
Now I could understand how a very narrow stone like those used in a lot of the jig systems might cause people to accidentally put too much pressure on the stone and tear out the grain as a result, but if you just let the diamond to the work like you're supposed to it shouldn't be a problem.
 
If I need to re-profile a blade...to take off a bunch of steel in a hurry...I always start out with the diamond plate. I use it on the Apex Edge Pro to "rough out" the new edge and then use silicon carbide stones (220, 320, 600, 1000 grit) after that...
Works great, I think.
 
You are always going to run into close minded people that take a first impression or hear somebody say it then repeat it like it was their own idea and stand by opinion no matter what evidence is shown to them that contradicts their opinion. There is another guy on youtube (forget the channel) that says waterstones are trash and that it is best to use an india stone without oil. The best way to learn any skill is to take a little bit from everyone. Somebody that has sharpened just 1 day might notice something you haven't after 5 years and of course people with 20 years experience have a wealth of knowledge as well. But nobody knows it all and nobody does it perfect. Just gotta pick and choose the information that works best for you and be open to new tips and tricks no matter how good you think you are.
 
I think SiC is awesome for most knives. But reprofiling I like to use diamond. The bonded diamond stones by Venev don't have the issue he's talking about. Also note the op video is from 2013.

But he's right, that some products will have the diamonds rip off. You have to use a light touch and let the diamonds do the work.
Example


What edge pro said about the metals being too hard and crumbling off reminds me of the few folks that have issues sharpening maxamet with that issue. Interesting.
 
Bull hockey!

I've been carrying this cut down Eze-Lap model L in my wallet for over 20 years. In the time it's sharpened up my pocket knife out somewhat countless times. maybe hundreds! It's still working just fine at putting a new edge on whatever knife I happen to have out someplace at any time or place. I've sharpened knives over my sister in laws home many times. I've even used it as a file when something needed some smoothing out. Still cutting steel just fine.

 
If diamonds are so bad for sharpening how ever will we ever manage to properly sharpen high vanadium carbides?
 
I've seen that video segment before. I tend to think there's some kind of 'perfect storm' of things going wrong there, in leading to a conclusion that diamond hones aren't compatible to steel blades. I used to notice, even as a novice sharpener at the time, that I was prone to leaning too heavily into my guided systems' diamond hones (Lansky, Gatco) when I used them. It just felt wrong, and the hones were clogging too fast, and I managed to kill one of them in basically one very heavy grinding job on an S30V blade. The 'Trifecta' combination of a small hone, a lot of wear-resistant steel to be removed, and heavy pressure is what did it in. BUT, I learned from that experience, and haven't come anywhere close to doing that kind of damage to another diamond hone since.

It's all in how they're used.


David
 
So when they wear out, do the diamonds get stuck in the blade like the guy says? This is a serious question.
 
OhLeever said:
So when they wear out, do the diamonds get stuck in the blade like the guy says? This is a serious question.
Click to expand...

If they stick in the blade at all, I doubt they'd stay there very long. More likely, loose diamond grit just gets deposited with the loose swarf on the hone. As mentioned earlier, there'd have to be something very wrong with the bond of the diamond to the nickel plating on the hone, if the diamond grit holds to the steel more readily than it does to the nickel.

I might see more potential for diamond grit getting embedded in steel during powered grinding, driven in under very high pressure/velocity conditions. But, diamond is already known to be unsuitable in powered (uncooled) grinding of steel anyway, due to it's chemical affinity for the steel's iron under very high grinding temperatures, and industry avoids using diamond that way, as a rule. Even then, it's usually more an issue of the iron from the blade chemically combining with the diamond (carbon) on the grinding tool itself, and irreparably clogging & ruining it. Those sorts of temperatures aren't possible when using a diamond hone by hand.


David
 
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One thing about Ben... he did a lot of testing over the years. This wasn't a "marketing ploy"... he has diamond stones available, and in reality, if the stones do wear out quicker, he could've made more money selling more diamond stones. He really tries to give the customer what he thought was the best way of sharpening.

If you listen to the clip in the video, part of this is a comparative analysis... he states the diamond stones won't hold up like the other stones... and he also says he's doing 100 knives/day. So the volume alone probably far surpasses what most of us do... and why it's hard to see what he sees. (He points that out too, that many can use diamonds, 'cause they don't do a lot of knives).

I'm not sure if he ever actually tested his statement someway... IOW, did he examine blades and see diamonds embedded in the steel, or did he just observe that they wore out quicker, and theorized the reason. But my takeaway from his reason for not using diamonds was that they just didn't hold up like other stones did. If he didn't state the "diamonds get pulled out" part... might not be such an issue?
 
It's not good to use diamonds on softer metal as well. That could be what he's referring to.
 
This isn't 100% applicable but it's related to this discussion. There is a website called scienceofsharp with some really interesting descriptions and high-magnification electron microscope photos of new diamond stones. I thought it was worthwhile to read through so I thought I'd share it for those who haven't seen it before:

https://scienceofsharp.wordpress.com/2015/09/10/diamond-plate-break-in/

https://scienceofsharp.wordpress.com/2015/09/28/diamond-plate-break-in-part-2/

See also: https://scienceofsharp.wordpress.com/2015/03/01/the-diamond-plate-progression/
 
The extreme high volume of blades is another element of the 'perfect storm' of things WAY out-of-the-ordinary, as compared to the sharpening habits of most of the targeted users of his device, who'll never approach that kind of volume on a per-day basis, or even per-month, for that matter. I doubt the EdgePro was originally intended to be a high-volume grinding device (that's what belt grinders are for), but instead designed as a tool for precision refinement and attention to detail. It all reminds me of the accelerated stress-testing manufacturers do with various products through their QC process, attempting to duplicate what they estimate to be a product's useful lifetime of wear, with intense and (possibly) abusive testing done in the span of just a few hours or days.

But having said that, it's still quite a leap of judgment to flatly declare, based only on those volume-skewed results, that diamond hones simply aren't compatible for use on steel blades. A statement like that is too easily taken out of proper context, as we're now seeing here.


David
 
I seriously think that either the diamond stones tested were being misused, were cheap and faulty, or both.
 
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