Diamonds No Good For Steel?

Discussion in 'Maintenance, Tinkering & Embellishment' started by ejames13, Nov 1, 2017.

  1. ejames13


    Mar 30, 2015
    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.

  2. FortyTwoBlades

    FortyTwoBlades Baryonyx walkeri Dealer / Materials Provider

    Mar 8, 2008
    Only if they're totally garbage stones with a bad bond.
    Lapedog, 115Italian and danbot like this.
  3. danbot

    danbot Gold Member Gold Member

    Oct 31, 2009
    And for the price of quality diamond hones, people wouldn't still be using them if they didn't work.
    115Italian and FortyTwoBlades like this.
  4. FortyTwoBlades

    FortyTwoBlades Baryonyx walkeri Dealer / Materials Provider

    Mar 8, 2008
    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.
    Lapedog, miso2 and 115Italian like this.
  5. Sonnydaze

    Sonnydaze Gold Member Gold Member

    Jul 6, 2009
    If I need to re-profile a 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.
    115Italian likes this.
  6. cap'njake


    Aug 15, 2016
    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.
    Lapedog and danbot like this.
  7. Mo2


    Apr 8, 2016
    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.

    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.
  8. jackknife

    jackknife Gold Member Gold Member Basic Member

    Oct 2, 2004
    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.

  9. MyLegsAreOk


    Aug 31, 2017
    If diamonds are so bad for sharpening how ever will we ever manage to properly sharpen high vanadium carbides?
    Lapedog likes this.
  10. 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.

    Kels73, Lapedog, danbot and 2 others like this.
  11. jbarsquat

    jbarsquat Gold Member Gold Member

    Feb 22, 2017
    I’ve never had any issue with diamonds in sharpening. I think he just doesn’t want people buying the wicked edge instead of his edge pro ;)
    Kels73, Bill DeShivs and jpm2 like this.
  12. Bill DeShivs

    Bill DeShivs KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jun 6, 2000
    Diamond hones will wear out- just like any sharpener.
    When they do, you buy another one.
    FortyTwoBlades likes this.
  13. OhLeever


    Oct 23, 2017
    So when they wear out, do the diamonds get stuck in the blade like the guy says? This is a serious question.
  14. 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.

    Last edited: Nov 2, 2017
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  15. cbwx34


    Dec 27, 2004
    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?
  16. Mo2


    Apr 8, 2016
    It's not good to use diamonds on softer metal as well. That could be what he's referring to.
  17. jalapeno


    Jan 16, 2017
    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:

    See also:
    Hytekrednek likes this.
  18. 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.

    Kels73 likes this.
  19. FortyTwoBlades

    FortyTwoBlades Baryonyx walkeri Dealer / Materials Provider

    Mar 8, 2008
    I seriously think that either the diamond stones tested were being misused, were cheap and faulty, or both.
    Mo2 likes this.
  20. Me too. Just too many things possibly going astray from 'normal' there. Would've been interesting to be a fly-on-the-wall, to watch what was going on.

    FortyTwoBlades likes this.

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