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?