How sharp is sharp enough? (ZDP)

R

rckendall

Joined
Oct 26, 2006
Messages
87
I recently purchased a Leek with ZDP189 blade steel so I could see what this new stuff was really like. It was not very sharp out of the box, so I thought I'd tackle the job myself. I've only successfully sharpened one blade before, a carbon steel fixed blade.

I've tried to sharpen the Leek 4 times now, and although it's getting better, it will still not push cut newspaper. I had to check my sanity today and tried push cutting with a razor blade, and sure enough it did.

I have used a water stone to get a relief bevel twice now and that bevel is still visible. I use a DMT guided rod system on the lowest setting. I finish with a set of ceramic rods fixed in a piece of hardwood with included angle of 34 degrees.

I feel for the burr with my fingernail while in the first stage of DMT process and then lightly go through the rest of the stones and ceramic rods.

It is the sharpest knife I've ever carried but isn't there something missing in my results? I hope I've described my process well enough, I feel like a real beginner amongst you folks.

Any suggestions?
Thanks
Richard
 
It should be pushcutting newspaper with your coarsest stone. Until that happens, the finer abrasives won't help. Get a burr from tip to ricasso on one side, repeat on the other, remove the burr with the same abrasive. Repeat with finer abrasives as desired.
 
ZDP-189 is very hard to grind, the bevel on the Leek is far too thick. Grind a low relief, <15 degrees all the way to the edge, cut off the weakened steel, microbevel to finish. Like Thom said, it can be very sharp even with coarse hones, if it is not, then technique (or steel) is the issue.

-Cliff
 
Thanks to both of you for your help. I went through the process again & it does pushcut in spots. I'm not sure what's up with that but I'm encouraged and will keep at it as time allows.

Thom, thanks for tip that it should do it's thing at the course stone. I was, also, able to feel the burr all the way even with my finger, not just my nail. I did both sides and lightly removed the burr, but just wouldn't pushcut.

I first marked the edge and went at it with my waterstone. Got a good relief and then to the DMT course. Twice I had a good burr but never got it so that it would pushcut. As my time was running out, I went through the remaining grits and ceramic rods and it would then pushcut in a few select spots. Other spots it would kind of tear in a straight line, not a clean cut.

After reading Cliff's post again, I see that I should have taken the relief grind all the wat to the tip. Is there that much "unstable" material at the edge? Is that what is causing the spotty results I now have?

Also, the diamond stones get gray after some fair amount of use. Is this the blade metal? I ran water over it to clean it up but is this normal?

I also found that with the waterstone, I count strokes to keep track of things, but with the diamond stones, I would more likely count minutes. It is taking a long time. Next time I'll do as Cliff suggested and take the relief all the way to the edge first.

Anyway, thanks to both of you for the help.
Richard
 
Yes, the relief should go right to the edge. You then grind off the weakened metal and micro-bevel as required.

-Cliff
 
One thing about push cutting newsprint is that the tip of the blade must be very pointy (sharp) and it is easy to round off the tip of a blade when running it through croc stick type appliances. Try the techniques described in this video:

hmm...it seems i posted the wrong link. I can't get the correct one...just do a Youtube search for "sharpmaker" and there should be a video who's description mentions avoiding and correcting tip blunting.

its for the sharpmaker, but the principles still apply.
 
why not send it to Kershaw and have them sharpen it for ya? Im sure that your having fun doing it ur self. Just an idea. Consider it the last resort i guess
 
If you have the DMT system then (IMO) stick with the diamond hones all the way to extra fine and then finish with a loaded leather strop.
Hard stainless steels seem to have persistent burrs that diamonds are best for removing.
Try also looking at the edge with a magnifier to see if you are actually grinding right to the edge. Mark the edge with a marking pen before each grind to increase contrast.
Greg
 
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