Spydie diamonds longevity

Discussion in 'Maintenance, Tinkering & Embellishment' started by Buck268, Feb 13, 2020.

  1. Buck268


    Nov 5, 2006
    How much life are people seeing from their Spyderco Sharpmaker diamond rods? I have a pair that's been used occasionally since 2011 but recently it seems like they are loosing their bite. Still functional but definitely slowing down... I think I worn them out re-profiling my KaBar USMC from the ridiculously obtuse edge it had only down to 40 degrees inclusive. I wanted to go 30 but figured (correctly) I didn't have the patience.

    Thinking about ordering some replacements but not sure if there is any reason to go with CBN instead. Read as many threads as I could including one on the spyderco forums where Sal predicted most people wouldn't perceive any functional difference between their diamond and cbn stones....
    bucketstove likes this.
  2. Bearbreeder


    Jan 9, 2018
    Dont bother with the diamond spydie rods

    Just get the ruixin diamond edge pro clone plates off aliexpress

    They come as low as 80 grit, and cost 2-4$ each shipped

    They are the perfect size to elastic ban to the sharpmaker rods

    They work just fine for reprofilling and other low grit sharpening

    As with any diamonds, use minimal pressure and let the stone do the work
    Buck268, kreisler and bucketstove like this.
  3. bucketstove


    Sep 23, 2014
    the cbn rods are an experiment,
    use lube,
    both stones ought to last if you're gentle ( see bottom of post )
    as spyderco sal glesser says

    Spyderco Diamond Rod Durability
    by sal » Mon Mar 12, 2007 3:02 pm
    Hi John,

    Diamonds don't wear out! They are among the most abrasive resistant materials on the planet.

    What happens is; first they "cap". This means that the very fine edges will chip due to excessive pressure or impact. This is the first 10 knives or so mentioned above.

    Then what happens is the diamond is dislodged from the matrix holding it to the steel platform. The diamond is dislodged from the matrix by the user pressing too hard or "striking" the diamond. the diamond is pushed into the steel under it, which creates a cavity surrounding the diamond, permiting the diamond to move....back and forth....until it cuts its way out of the matrix.

    The diamond requires almost no pressure to cut steel. drag a diamond hone very lightly across the blade of your most cherished collector pieces :eek: I guarantee it will scratch the blade.

    I continually hear about people that say their diamonds wore out. Not so. They wore them out by pressing too hard. Even the ones that say they are not pressing too hard, just don't know how lightly to use diamonds if you want them to last.

    Diamonds are great, they'll cut the hardest steel. Pressing harder doesn't make them cut faster, it only dislodges the diamonds from the matrix. If you treat a diamond abrasive like a whetstone, you are pressing too hard.

    I personally like to lube with a little water which I beleive reduces the cut but saves the diamond.

    That is my opinion based on a background including: experience in Mil spec plating. 55 years of knife nut passion, manufacturing diamond hones, sharpening experience with just about all abrasives.

    I would not let the scouts use diamond hones without prior successful sharpening experience. I would bring a very coarse cheap 2x8 or 3x8 sharpening stone and honing oil and give them a real lesson.


    Re: Tri Angle Stone Diamond 204D vs Cubic Boron Nitride 204CBN
    by sal » Mon Mar 19, 2018 3:34 pm
    Hi Tjkoko,

    Welcome to our forum.

    We've been making diamonds for our Sharpmaker since 1981. Even before we had the medium grit stones, we had diamond sleeves. When we could, we made diamond triangles. The problem with diamonds is that they are attached to a steel embryo using a plating process. The diamonds are very hard. Harder than the steel embryo or the plating material that adheres the diamond to the steel. People using the diamonds to sharpen will generally press too hard, which loosens the diamonds from the plated material so longevity is not as desired. Diamonds work best with a very light touch, as the diamonds are much harder than the blade, it doesn't take much pressure to be effective. Getting customers to do this has been very challenging. Most people think (or simply intuit) that "if I press harder, they will cut faster".

    CBN has some advantages over diamonds in cutting steel and it is hard enough to sharpen any steel, I felt that if we made our triangles in CBN as well as diamonds, people could try both and in time we might see a difference or advantage to one or the other.

    I use CBN and I also use diamonds, but I use a very light touch and take the time to do a careful job not to damage the diamond / CBN. I believe that the CBN might be competitive in that it cuts as well, and I believe adheres better to the plating. Hope that helps?



    Re: CBN rods: Corners "different abrasive" from the factory?
    by sal » Wed Oct 23, 2019 9:49 am
    I generally don't recommend using the diamond or CBN corners for use unless one is very careful to go very slowly and very lightly or you will tear the stones out of the matrix. Most will press much harder than necessary. the nature of a serration is to "wrap" around the corner which is very hard on the matrix.


    Re: Double stuff 2?
    by sal » Mon Nov 12, 2018 2:51 pm
    Hi Spackla,

    Welcome to our forum.

    The CBN is plated onto steel embryo with a nickle alloy plating. The CBN shouldn't wear much, unless you are pressing too hard. It doesn't take much pressure for the CBN to cut the steel. Many people think that if you press harder, it cuts faster, but that isn't so. Pressing harder just dislodges the CBN stone from the matrix. So it isn't a wear problem but a pressure problem that "wears" diamond and CBN stones.



    I've used 5-10 grams on my harbor freight diamond block with the tip of a knife and didn't scrape anything off that I could see.
    I've also used ... 2-3 pounds (? definitely more than 1, unsure, accident ) with a tip and scraped everything to bare steel (nickel+diamonds gone).
    Think about that 2lbf/square mm to pounds/square inch = 1290 psi compared to
    5 grams/square mm to pounds/square inch = ~7psi

    Make it a more dull tip 2mmx2mm = 322psi

    If your edge bevel is 2mm wide, .5lb on a 2inch stone is about 3psi. half inch is 12psi and quarter inch is 25 psi

    If you use lube (water) and keep the force under 1/2 lb (or 226.8 grams ) cbn/diamond stones should last forever

    see CBN Rods - Page 7 - Spyderco Forums
    Diamond rods inferior to CBN rods? - Spyderco Forums

    update: a quote light force, 1/2 lbs but small contact area meant the pressure was high 10-20 psi this translates to 226.8 grams , this is on the flats not the corners of triangles
    Mr.Wizard and kreisler like this.
  4. Mr.Wizard


    Feb 28, 2015
    I am going to have to look into this. There is an obsession with light pressure illustrated above that doesn't seem to exist in industrial grinding manuals. It could be that premature wear is seen as acceptable, but if claims such as: "Pressing harder doesn't make them cut faster, it only dislodges the diamonds from the matrix." are true this should be in the literature and (cutting parameters that produce) extremely light pressure should be standard industry practice.
  5. eKretz


    Aug 30, 2009
    Sorry but that is just inaccurate information. Diamonds do indeed wear. EVERYTHING wears. While diamonds are indeed the hardest known natural material, no substance on Earth is invulnerable to wear. We've been over this here before, and I've linked scientific papers showing wear studies on diamond.

    I've also personally seen monocrystalline diamond wear when used to dress grinding wheels. Just about everyone here has seen worn diamonds too - know anyone with a diamond ring, necklace, bracelet or earrings? How do you think the facets on the diamonds are formed, magic? They are formed via abrasion. Diamond grit is used to cut and form the gemstones. Other materials will wear diamond as well, but it takes longer.

    Increased pressure will indeed cause accelerated wear to the diamonds, as well as cause the diamonds to cut faster and deeper - so long as they stay put in the matrix they are embedded in. Obviously if they pull out then wear will not be an issue. Not every diamond will pull out, and pressure on individual diamonds is dependent on surface area of the item in contact with the hone. In other words you can push a lot harder without any worries on a flat wide plane back than on a knife bevel that's 1/32" wide.
    Mr.Wizard likes this.
  6. Bearbreeder


    Jan 9, 2018
    if you want faster more aggressive sharperning, go down in grit

    Theres no reason to press hard into diamonds for sharpening purposes

    Why risk breaking off the diamonds on that $$$$ diamond stone?

    Of course you can get the el cheapo ruixin diamond plates and not overly worry about it

    And at those prices you can get a lot of grits and use em with the sharpmaker
  7. eKretz


    Aug 30, 2009
    Yes, as I already mentioned there absolutely is a reason to press hard - if you have a large surface area in contact at once. Conversely if your surface area in contact is small then light pressure is a good idea. It is something you just have to judge by experience.

    Excess pressure absolutely can remove or fracture diamonds, and if it doesn't do that it definitely will accelerate wear. I tend to use the lightest pressure possible that still produces swarf, that's a pretty good guide in my experience. As the electro-plated diamond plates dull you will need to use a little more pressure to keep them cutting.

    Resin bond or metal bond diamond abrasives are built to release dull diamonds as they dull and pressure increases. At that point it is good to dress them to drop the binding matrix back away from the tips of the grit a little. Mostly these types of abrasive are used in powered equipment but there have been a few released as bench, guided system and hand hones.
  8. Bearbreeder


    Jan 9, 2018
    Even on plates there is no need to press hard

    If your diamonds arent cutting fast enough ought you need a lower grit, not more pressure

    Or just spend a bit more time
  9. Mr.Wizard


    Feb 28, 2015
    I believe you meant force and it's leading to confusion. The force should be moderated to keep the pressure the same. @Bearbreeder you may need to press hard just to produce correct pressure if you are flattening the back side of a large plane blade for example; even standing up and pressing as hard as you can is unlikely to produce as much pressure as a feather-light micro-beveling stroke on a diamond rod, because the force will be distributed over an area perhaps five orders of magnitude larger. (Assuming both blade and plate are flat and both are thick enough not to deflect significantly under the load.)
    Last edited: Feb 15, 2020 at 5:03 PM
    eKretz likes this.
  10. eKretz


    Aug 30, 2009
    Absolutely correct if you want to get into semantics, but pressure in common parlance as used here means force by pressing. Just as used above in the context "no need to press hard."

    I recall Todd Simpson doing a comparison of diamond plate grits and finding that using a coarser plate actually requires considerably more pressure than a finer one for efficient cutting. This due to the larger surface area of the larger diamonds in contact while using the diamond plate. This is probably why very coarse diamonds plates are relatively sparsely populated with diamonds compared to finer plates.
    Last edited: Feb 15, 2020 at 7:19 PM
    Mr.Wizard likes this.
  11. Bearbreeder


    Jan 9, 2018
    I use 80 grit diamond with very little pressure

    In fact with very low grit diamonds the blade edge will start catching on the diamond with higher pressure on the forward stroke

    Not to mention you are more likely to get inconsistent angles with high pressure freehanding on plates

    Just use enough pressure for the diamond to cut

    I mean its diamond, it will cut it faster than waterstones anyways

    And your $$$$ atoma and dmt plates will last longer
  12. Bearbreeder


    Jan 9, 2018
    Double post
  13. Buck268


    Nov 5, 2006
    Great suggestion, I'll check it out. Any idea which ones compare with the finish on the spydies?
  14. Bearbreeder


    Jan 9, 2018
    The 400-500 grit ones

    Its not exact and the spydie ones are of course better quality

    But then again they are like 6 times the price

    Also pick up a set of the 80 or 120 grit for serious reprofilling

    I always use em for cheaper knives, i got a set of spydie diamonds too which i dont use too much

    No sense wearing em out on el cheapo kitchen knives

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