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ZDP Defeats Spyderco's Sharpmaker!

Discussion in 'Knives' started by Lord Bear, Jun 1, 2010.

    Lord Bear Loaded Pockets

    After wrestling with my ZDP folders (all from Spyderco) for some months now, I finally gave up. In order to get a really sharp edge, I found I had to apply extra pressure than on other steels. This causes the ABS (plastic) "base" to flex/give/bend making it extremely difficult to maintain the proper angle through the downstroke. The resulting edge didn't last long compared to other steels, which caused me puzzlement until I figured out the previously mentioned "cause". (The flexing due to extra pressure.) ZDP is supposed to maintain an edge for longer use, not shorter.
    So I dug through my collection of "stuff" and brought out the DMT Diamond Aligner Kit and lo and behold, PAYDIRT! It was quick, fast and easy. I dispensed with the normal flipping over for every stroke and started with the X-coarse by giving 50 strokes on one side, THEN flipping it over to give 50 strokes on the other side. Then proceeded through the Coarse, Fine and finally the X-Fine. Just to make sure, I repeated the Fine and X-Fine 10X each by flipping over with every stroke to counter any unevenness that may have been ground in by stroking one side only , repeatedly.
    I am wondering if flipping over with every stroke might not even be necessary since the factories apparently grind one edge, THEN the other? Anyone with more knowledge on this particular point?

    Yablanowitz Loaded Pockets

    Actually, applying extra pressure is counterproductive. ZDP-189 is hard enough to feel like it is sliding over the stone , but it is being abraded. Very slowly, but it is happening. Very light pressure and a billion strokes are what is required for ZDP on the SharpMaker. Using more pressure causes a burr which may feel sharp but won't last long in use, and it generally breaks off leaving behind a rough flat edge. That is true no matter what hones you use (voice of much experience).

    Nothing wrong with grinding down one side at a time, as long as you keep the bevels fairly even so the edge is more or less centered, but alternate sides at the end with very light pressure to grind the burr away rather than bending it back and forth until it breaks off, leaving that rough flat edge.

    Lord Bear Loaded Pockets

    A billion strokes. Oof! Seems like exactly what I went through in the last few months LOL! I see now that my frustration is where the problem lies; not in the Sharpmaker. Gradually over time (billion strokes) the frustration builds, patience runs short, and more and more pressure is applied. A BURRY bad result ensues. I ended up breaking off the edge BURRY quickly and this makes perfect sense. I did indeed use less pressure with the guided DMT Aligner Kit. The diamonds give a more...tactile sensation that SOMETHING (anything!) is actually happening as the blade travels down the hone. (I cannot describe as other than a more...scratchy sensation. Like running a fingernail along sandpaper type of feeling.) Perhaps also more material is removed with less effort (due no doubt to the diamond crusted surface of the hone) so pressure is not unduly applied resulting in a "better", more aligned, edge.
    Perhaps the Sharpmaker is due for another run. Starting with the diamond triangles employing a very light touch of course. Thanks for the confirmation and advice Yablanowitz. (Carrot said to listen to you. I thank Carrot also for keeping an eye out for all us enthusiasts. For both Yablanowitz and Carrot, a hearty :bow::bow::bow: )

    carrot Loaded Pockets

    Really? I don't let my ZDP get all that dull but a handful of light strokes on the brown stones and then a couple on the white stones will get it back to hair popping sharp! I've been blown away by this steel, personally. Not to mention it takes forever to dull it.

    Yab is (of course) absolutely correct that the extra pressure is creating a brittle edge, when in fact a light touch works the best.
    • Administrator

    Valerian Tea-powered admin

    True enough, while ZDP is very hard for a steel, the ceramic rods are still many times harder.

    You can easily do hundreds of light strokes while watching TV or something. Yes, I know, very bad advice: you should always keep your eyes on the blade. But that's what I do with stubborn blades, and I haven't cut myself yet. If you keep the pressure light and don't try to do it in a hurry, nothing is going to happen even if the blade slips. For good measure, keep your other hand at the other end of the Sharpmaker (instead of under the rods).

    Yablanowitz Loaded Pockets

    I had a really hard time adjusting to the feel of ZDP being sharpened, and didn't get satisfactory edges for quite a while, even on diamond hones. It helped when I had Tom Krein thin out a ZDP Endura to 0.010" at the back of the edge bevel. Even at 30 degrees included, the bevel is only about a millimeter wide, so it doesn't take so many strokes to get somewhere with it. That got me to lighten up, resulting in much better edges on all my ZDP blades. It works for S90V as well.

    Edit to add: it doesn't really require a billion strokes. It just feels like it while you're doing it.

    "I don't let my knives get dull" is both true and false for me. It isn't that I "let" them get dull, I do what I have to do at the time, and if the knife is dull afterward, that's life. My record so far is getting home at the end of a workday with eight blades in need of new edges. Not touch-ups, whole new bevels. They included ZDP-189, S30V and D-2 among the casualties.

    carrot Loaded Pockets

    Sounds like you have a fun job, Yab.

    Lord Bear Loaded Pockets

    As usual, Carrot, you point out the fallacies in my thinking. The problem children were the Endura and Stretch, both FRN/ZDP. The Endura along with the Caly 3 CF/ZDP were my first two ZDP blades. The Caly 3, for the 1 day I actually used it at work cutting cardboard was exactly as you put it. The Endura was my first experiment along Joe Talmadge's assertion that ultra-hard blades could be thinned out and work even better. Heretofore I had used the 40degree angle exclusively for my working knives until I attempted to back bevel zero edge the Endura, brand new out of the box using the diamond triangles. (I'm not sure if zero edge is correct. I mean that the edge has been ground to 30degree period, along with some unevenness, without a further 40 degree edge at the cutting surface. Hope this makes sense.) My Endura was saber ground. Billion strokes.
    Ordered a Stretch FRN/ZDP down the line and thinking that it would be fun to see how a flat ground blade would stack up back bevelled, a billion strokes followed.
    When I got my Caly 3 G10/VG10, I "retired" the original CF/ZDP Caly 3.
    Also use serrated FRN/ZDP, Endura and Delica for work. As with the Caly/ZDP, since I didn't try to back bevel these, (for obvious reasons), sharpening with Sharpmaker were not problematic with them.
    Thank you again for pointing out the realities I sometimes forget and gloss over in my postings.
    Lord Bear.
    Further edit: Using the DMT aligner, the edge I got was not as steep as the original 30degrees. They are shallower. Will have to wait for another "big" delivery of many pallets of boxes to see if they hold up as expected.

    Lord Bear Loaded Pockets

    Ordered a flat ground FRN/ZDP Endura. This one I will not back bevel and simply 40degree sharpen on the Sharpmaker as needed. Should be interesting.

    Yablanowitz Loaded Pockets

    If a few thousand linear feet of cardboard is a big workout for your knives, sharpening at 30 degrees included with no secondary bevel should work just fine, as long as you avoid staples. ZDP-189 works quite well at 20 degrees included with a 30 degree microbevel for such work. It does not deal well with hard surfaces at those angles, though.

    Lord Bear Loaded Pockets

    Recycled cardboard from China mostly (and other parts) is a HUGE percentage of what we go through. If ever moisture becomes an issue, these :censored: things are like trying to cut through drywall, I kid you not! (I live in Florida.) Some boxes recently were unbelievably impossible. They had been warehoused, tucked away in a forgotten corner for a few months. Then when we transported them to another location in open truck beds, it rained! Boxcutters, many different steeled blades, serrated even, (all mine), were defeated. In our work we generally remove the top flaps completely and simply place the entire box of 1 dollar items, etc on shelves. Staples are of course an ever present hazard. There's also packing tape, very resistant plastic retaining straps, saran wrap type pallet wraps, etc. There's also some wood and fabric.
    Any guided sharpeners that can go down to 20 degrees included so I can microbevel at 30 degrees that you can recommend? Diamond would be preferred if at all possible.
    Thanks Yab.

    Lord Bear Loaded Pockets

    Deleted off topic

    Yablanowitz Loaded Pockets

    Sorry man. I've been sharpening freehand for 45 years, so I really don't know much about guided systems. The only reason I've kept my SharpMaker is for serrations.