Spyderco's ZDP 189 Calypso Jr....WOWZA!

sodak said:
...maybe someone else can test it this way....
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Drop from 3 feet onto concrete, the tip cracks, is about 1 mm across. Drop from six feet, no further damage. Drop from 12 feet, the knife tends to rotate and land on the spine.

-Cliff
 
Note with the following knives when I list the heights they are corrected for the weight of the knife so they have the same impact energy as the Calypso Jr. when dropped from the same height.

I intended to do 3' then 6' drops, then do at leat 6 6' drops to check extended durability. I was being helped by a friend and we had communication issues so the method varied a little.

Small Sebenza, S30V, similar tip profile as the CJ, on the 3' drop, it cracked on the first impact, about 1.5mm across. On the 6' drop it was mangled, the damage was 2mm in width, impaction/fracture + tip bend

Salt, H1, thicker tip, drop at 6' bent the tip about 2 mm across on first impact.

CS Voyager (small), AUS-8A, simiar tip profile to CJ, first 3' drop, tip cracked about 0.5 mm across, just visible. Fourth 3' drop, the damage was same as CJ, but bent instead of cracking. Stopped here as a bent tip focuses drop impacts and makes further ones much worse.

Paramilitary, S30V, much more robust tip profile, took 6 drops from 3' and then 6 drops from 6' with only tip blunting. On the second 6' drop it stuck in the floor.

Kershaw Vapor, AUS-6A, similar tip profile to CJ, on the fourth impact at 3' the tip impacted a little, 2 more then 6 at 6' with no significant damage, just blunted.

Byrd Meadowlark, 8Cr13MoV, slightly thicker tip than CJ, 6' drop, tip cracked 2 mm across.

In regards to the level of impacts of the drops, it was popping pieces out of the concrete. No damage to the scales, locks or clips, the Sebenza's Ti slabs took a fair bit of cosmetic damage, but they were already heavily scratched.

Even with the inherent random nature of tip drops, the difference in behavior between the soft/hard steels is obvious in regards to bending and cracking as is the influence of tip geometry.

No real surprises except the Vapor, it had a near perfect balance of strength/toughness to resist bending and fracture. None of the blades took significant edge damage, just blunting.

It took 1-2 minutes with a coarse SiC waterstone to reset the points on all the knives, and similar to regrind the edges fresh and remove any weakened/impacted metal.

In short, ZDP-189 doesn't appear to be significantly more brittle than other similar high carbon stainless steels, and its hardness can actually be an advantage in preventing some damage due to greater strength.

I have also done a lot of metal cutting with it, can opening mostly. The first time I tried it I chipped the edge badly (visible damage), however I have done it several times after that with no problems.

Straight cuts, make an x, are easy, however I have tried to cut out the top of the can a couple of times and again chipped the blade, this will damage other high carbon stainless in similar profiles as well.

-Cliff
 
The lesson here is do not drop your knife tip first into concrete regardless of the steel it's made from.
 
Satrang said:
The lesson here is do not drop your knife tip first into concrete regardless of the steel it's made from.
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True. Bent steel is actually not 100% better than breaking because it is then weakened.
 
The problem with lower strength for toughness, which is what many aim for by underhardening steels is that you can end up with more damage. The tip on the Sebenza for example bent deeper than the Cj tip cracked off. Now it could be straightened, but as noted it loses strength.

Ideally you pick a steel which has the required toughness at the hardness you want to give the optimal combination of strength and toughness. Any of the tougher tool steels will handle the above with no fracture or bending without an excessively thick tip such as on the old style Strider tips.

The above is a worst case senario in regards to drops because it takes a fairly high fluke to get a perfect point impact, half of the drops just hit the blade on its side/back as I was trying to get them to go point first. Plus drops in general from above a few feet are kind of rare unless you work on scaffolding and the like.

The Vapor is interesting, nice cutting ability, nice steel (never would have juged it by the name, stronger than many AUS-8's I have see), opens among the smoothest folders I have seen, and the lock is decent enough for a liner/integral. Too bad there are QC issues with it, otherwise it would be a solid recommend.

I wish I had not ground the stud off initially when sharpening, I didn't think I would ever use it seriously. I carry it EDC alongside the Sebenza now as it gets used for harder work as the edge profile is fairly robust (~10 degrees per side).

In regards to damage, it isn't overly significant compared to regular use, my Sebenza for example has a visible recurve in the blade because I have actually cut that much with it, there is a hollow worn in the middle. I was going to joint it, but it works better this way.

-Cliff
 
I would love to know how good old 440C would hold up to these drop tests. Say, a 550 or 551 Griptilian?....even the Mini-Grips would work fine :)

Any chance of that?

Thanks for what you've damaged already Cliff. Much appreciated! ;)
 
SAKguy said:
I would love to know how good old 440C would hold up to these drop tests.
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MPU : 440C : tip profile similar to Paramilitary

3' : First drop no effect, second drop tip bends slightly, <0.5 mm across, third drop bends more, fourth drop, takes an S-bend/compaction, fifth drop, tip cracks, <1mm across, sixth drop, nothing further.

6' : all six drops do nothing significant, the tip on the end looks similar to the Paramilitary.

Misson tends to leave their steels softer than most which is likely why this 440C tended to bend rather than crack.

ccdog said:
Thanks for the info Cliff!
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No worries, any full sharpening (say a heavy session of carpet cutting) would restore the tips, the damage wasn't significant to any of them. They would see more wear in a month of EDC carry as primary.

-Cliff
 
Cliff,

Thanks very much for the info.

This would seem to me that the Grip's are pretty darn good bang for the buck. Also with adjustable pivot and a nice handle.
 
Cliff Stamp said:
In short, ZDP-189 doesn't appear to be significantly more brittle than other similar high carbon stainless steels, and its hardness can actually be an advantage in preventing some damage due to greater strength.
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Thanks, Cliff. That's great stuff. I must admit, I was a bit worried the steel might run out to be too brittle for everyday use.

It may still be a bit early, but it now looks to me as though ZDP-189 is going to be the steel of the year. If Spyderco introduces more knives in this steel, it's going to make life difficult for the other manufacturers.

Hans
 
Hi Blondie, Scott, thanx. Glad to have the opportunity to provide the steel.

We do have more ZDP planned. A Delica scheduled for January and talk of a Chinese Folder.

sal
 
Sal, you keep makin' em, I'll keep buyin' em. :D

That said, a para-millie or mini-manix in zdp 189/420j2 would be my dream knife. I realize there's an issue with the blade's country of origin, no chance of a japanese blade on an american handle?
 
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