ZDP-189 edge chipping test:

[unit]

Even without much magnification, there is some serious abrasion evident in that area of the blade. Shoes can be a bit complex perhaps? There must be something somewhere in that thing that is more than basic nylon/cotton/poly fabric and rubber.

People sometimes trip on these demonstrations (I do not call them tests). I got an odd comment on one I had posted elsewhere last night. You do not need to cut cans or shoes every day to see some value in these demonstrations. People trip, but being able to see how edges fail/degrade (and using your brain to ponder those images) can teach you a thing or two about how materials behave.

Thanks for sharing.

[mongatu]

Many years ago, I had a job as a lab technician and one of my jobs involved using a very expensive Swiss optical dissecting scope with very fine Swiss tweezers, so fine they could pick up a single hair easily. The tips of these tweezers used to wear or get damaged and frequently needed sharpening which was one of my responsibilities. I used to sharpen them under the scope with a small stone. The interesting thing was that under that kind of magnification in real time, it was easy to see how every single stroke had a significant effect on the metal and what that effect was. That experience was really helpful in that as a result of it I have a much better idea about what is actually happening at the edge as I sharpen. I think looking at magnified images like these or using even a 10x jewelers loupe (as Sal has said he does, btw) is also very helpful in learning about what is going on with the metal at the actual edge and that ultimately it makes one a better sharpener.

Nowadays, I mostly use the loupe to observe the scratch pattern and how it changes as I sharpen and to help determine where I'm grinding on the bevel. I think it's really helpful overall.

[jimnolimit]

as a comparison the edge of the ZDP looked better than when i used 60 grit sandpaper to re-bevel VG-10.


here is the edge of the ZDP after shoe cutting (top), compared to VG-10 after 60 grit (bottom):

ZDP



VG-10

[jimnolimit]

i decided to cut the other sneaker up using my spyderco para 2 s30v. i set the edge around 18-20 degrees, with the same stone i finished the ZDP with. the s30v would easily cut newspaper against the grain before the test, just like the ZDP. i cut the same sneaker as i did with the ZDP (just the other side). i also cut this sneaker into about 27-28 pieces just like i did with the ZDP. the only thing i did differently was that i oiled a paper towel and kept wiping the blade so it wouldn't get gummed up. i didn't use oil on the ZDP until i was close to the end of the test which made cutting more difficult. this caused me to use some more effort with the ZDP as opposed to the s30v.






this is the edge and the part of the edge i marked before the test, 40x-50x magnification:





this is the edge after the test, 40x-50x magnification:





this is the edge at 375x magnification. the s30v took on more damage than the ZDP. also, the s30v wouldn't cut either paper or cardboard after the test. ZDP had some trouble with newspaper, but still cut cardboard pretty easily. note the scoring on the edge just like the ZDP had. i don't know if that is caused by microscopic pieces of s30v getting caught in the rubber or if the rubber has abrasive in it (example: they use silica in the rubber for car tires).

[A.P.F.]

Jim, I think you will find that the edge erosion and subsequent scoring, is due to silica and rock fragments embedded in the uppers and sole of the shoe. It is actually such microscopic silica that causes the stitches to fail in shoes.

[defenestrate]

I'd just like to say that this is a very cool and informative thread. The differences in those magnified pics and the damage they depict speaks volumes.

[unit]

Jim, I think you will find that the edge erosion and subsequent scoring, is due to silica and rock fragments embedded in the uppers and sole of the shoe. It is actually such microscopic silica that causes the stitches to fail in shoes.

Adding silica to rubber is pretty common to aid traction (particularly on ice). It can be pretty rough on edges...but I have also used it (silica enriched rubber) in a pinch to strop an edge to a more usable state.

[mongatu]

I've always found S30V to have a little more tendency to develop small chips when subjected to moderately heavy use than I like to see. Your test and photo confirms what I've observed in my own usage. It's still a pretty decent blade steel though that I find fairly easy to sharpen and it takes a nice edge.

[jimnolimit]

for everyone to compare, this the ZDP and S30V after cutting the shoes:





im thinking about starting a thread where i test different steels under the same conditions.


.

[chuck_roxas45]

im thinking about starting a thread where i test different steels under the same conditions.

That will be interesting. I hope you'll have it up soon. :D

Thanks for taking the time and exerting the effort(not to mention the use of your spydies) to do this.

[Blerv]

Well I'm sold. Thank you! :)

I'll still gladly pick knives I like if they come with s30v or vg10. That said, I won't sort zdp blades into the pile of "more gentle users" I have in the past.

I would love to see m4 go at it. Sorry about your shoes!

[Hammerlock]

Excellent test; this actually gives me more confidence now; I've been babying my ZDP-189 way too much.

[dbcad]

I'm of the same mind as Hammerlock, yet something in my mind keeps telling me to polish the edge more, take away as many of those microscopic scratches on the edge as you can and minimize the points of stress accumulation. Discontinuity on the edge will always lead to stress accumulation. Smoother is better and stronger :) A finer finish will help with any material.

[jimnolimit]

I would love to see m4 go at it. Sorry about your shoes!

i change my sneakers every 3-5 months and they're always US made new balances. the pair i use now will get retired within the next week.

when bento box ships out my M4 manix2, there is a very good chance a sneaker will get sacrificed .

[jimnolimit]

That will be interesting. I hope you'll have it up soon. :D

Thanks for taking the time and exerting the effort(not to mention the use of your spydies) to do this.

i made the thread: http://spyderco.com/forums/showthread.p ... post667764

i have pics of the:
1. endura 4 ZDP
2. para 2 s30v
3. 52100 mule
4. buck vantage (420HC)


.

[chuck_roxas45]

i made the thread: http://spyderco.com/forums/showthread.p ... post667764

i have pics of the:
1. endura 4 ZDP
2. para 2 s30v
3. 52100 mule
4. buck vantage (420HC)


.

Thanks for all the time and effort expended. Outstanding!