ZDP edges -- how thin is too thin?

MeDoctor

MeDoctor

Joined
Dec 8, 2003
Messages
279
I posted this question in the ZDP Leek thread over on the blade discussion forum, but thought it might be more appropriate to post it here as a new thead...

Before I ruin a perfectly good blade I thought I'd better ask a question. My ZDP Leek just arrived, and it's just sharp enough to shave -- but the bevels are 27 degrees per side (54 degrees inclusive). Is the obtuse bevel an attempt to reduce edge chipping? How acute can I go without creating an overly fragile edge? My laminated ZDP Caly Jr. is at 11 degrees with a 15 degree micro-bevel. It's fairly prone to chipping when used hard. I bought a ZDP Caly Jr. for my son and he brings it to me every month or so for re-sharpening with numerous chips in it. I ground his to 15/17 simply because I know he abuses his knives, but I suspect he'd bring it back chipped even if I ground it at 30 degrees per side -- he's that hard on 'em.

So, is there an "ideal" angle for the ZDP Leek?

Is there a limit that we should avoid exceeding?

Thanks,
Mark
 
MeDoctor said:
My ZDP Leek just arrived, and it's just sharp enough to shave -- but the bevels are 27 degrees per side (54 degrees inclusive).
Click to expand...

That is pretty silly.

How acute can I go without creating an overly fragile edge?
Click to expand...

What are you cutting.

-Cliff
 
54 degrees is obviously way too thick. It's not going to be much good as a cutter at that angle, and if a knife can't cut, what good is it?

Sorry, I know that wasn't helpful, but 54 degrees! That's nuts!
 
Lucky Bob said:
let's assume EDC stuff, paper, cardboard, string, rope, etc.
Click to expand...

That'd be a safe assumption. I carry a Native S30V in the other pocket for rougher use. Craig Green answered the biggest part of my question over in the the other thread:

"Did we grind the blades thicker because of chipping / breakage concerns - YES, the Leek blade - due to design has a delicate point and grinding them slightly thicker helps with cutting edge and tip strength."

Since the ZDP Leek fairly laughs at my EdgePro's coarse stone I was using a coarse diamond hone glued to a stone blank to re-profile the blade. I bought a set of the cheap 2"x6" hones from Harbor Fakes and cut them to 1"x6". Unfortunately they're the ones with the perforated surface -- I found out just how fragile the Leek's tip can be when it hung up in the hone and broke off. After one very loud expletive (thank God the wife wasn't home) I took it out to the belt grinder. The blade is now ground with a 15 degree back bevel and a primary of 19 degrees with a 21 degree micro-bevel. While grinding in the new tip I lifted the handle a bit so the tip is at roughly 25 degrees -- and the tip's ground to a less acute point than it once had. It now push cuts and shaves almost as well as my ZDP Caly Jr. at 15 degrees.

Mark
 
That's unbelievable. Anybody else measure angles like this on a ZDP Leek? My G-10 Leek came from the factory at exactly 20° per side. Given the fact that S30V has similar issues with chipping, I find it highly surprising that they'd grind the ZDP blade so obtuse.

Oh, I almost forgot. I have a 1660PGT; the regular production G-10 Leek may not be as acute as mine.
 
Here's the new tip:

tip.jpg
 
Lucky Bob said:
let's assume EDC stuff, paper, cardboard, string, rope, etc.
Click to expand...

There really isn't a minimum for that, it would be limited more by the primary grind. My three Spyderco ZDP-189's are about 10 degrees primary and 15 degrees secondary. You need to be careful cutting thicker metals like cans, but you are not limited to paper and such.

-Cliff
 
Hi, I don't post here very often, but I received my leek with the same obtuse edge the original poster was talking about. Using the sharpie, I could see that the sharpmaker stones were hitting way high at 30 degrees, and they still wouldn't hit the edge at 40 degrees, so I know my zdp leek came in at >40 degrees inclusive. I intend to carry and use my leek, so I knew a reprofiling job was in order. I don't have a belt sander (yet) or edgepro, so I reprofiled freehand on a course diamond benchstone (a dmt I believe). I brought the angle down quite a bit, and tried to maintain the tip and get a uniform bevel side to side. Then I started on the sharpmaker at 30 degrees and established a secondary bevel and went through all the steps. This resulted in a shaving sharp leek that would shave/cut newsprint, which it wouldn't do with the factory edge. My zdp spydercos have spoiled me to a point, and the edge of the leek still doesn't seem as sharp as my hollow ground zdp jess horn (of course the edge of the flat ground leek is thicker), but I really like the leek a lot. My hat does go off to kershaw for experimenting with better materials and steels, they're attracting customers like me, this is my first kershaw and first assisted opener. I know it's better to err on the side of caution with a factory edge on a knife, but I have come to expect a thin enough edge that I can touch it up on the sharpmaker without a major reprofiling job. Other than that, I'm really liking this knife.
 
You must log in or register to reply here.
Back
Top