ZDP-189 vs. SGPS

[Franco G]

There is an interesting thread by Cliff Stamp about comparison between the ZDP-189 Jess Horn and SGPS U2 (Fallkniven).
The results are very interesting, but confusing (edge retention).
You may take a look at
http://www.bladeforums.com/forums/showt ... p?t=420917

Franco

[JD Spydo]

There is an interesting thread by Cliff Stamp about comparison between the ZDP-189 Jess Horn and SGPS U2 (Fallkniven).
The results are very interesting, but confusing (edge retention).
You may take a look at
http://www.bladeforums.com/forums/showt ... p?t=420917

Franco

I personally have not yet become very knowledgable about "SGPS U2". But if Fallkniven is using it I am sure it is a great blade steel. However it would have to be some extraordinary stuff to compete with ZDP-189.

Fallkniven has a knife I want which is called the "THOR" and it has laminated VG-10 which I have heard is great. But please do tell us more :)

[cobrajoe]

Indeed, do tell us more. I am not a member of blade forums, so it won't let me see.

[bh49]

Indeed, do tell us more. I am not a member of blade forums, so it won't let me see.

You do not have to be a member of BF to read.
Also you can join. Most of the people here members of BF. You will find a lot of information, but it is not as nice as this forum.

[The Deacon]

You do not have to be a member of BF to read.

Not true. It is posted in one of the many sub-forums (including the Spyderco Forum there) there that can only be read by logged-in registered users. I'm a gold member there, but their setup annoys me no end, as there are times and places when I would like to view the forums without having to log in.

[bh49]

Not true. It is posted in one of the many sub-forums (including the Spyderco Forum there) there that can only be read by logged-in registered users. I'm a gold member there, but their setup annoys me no end, as there are times and places when I would like to view the forums without having to log in.

Sorry, I was wrong. I was reading BF for a month before I joined it. But either rules were changed, or I was visiting non-restricted areas.
Sorry again for misleading.

[HoB]

Well, bottom line really is that Cliff found on cardboard (lots of it) that SGPS actually holds an edge longer than ZDP-189. Cliff is pretty careful in the post to point out that the errorbars are substantial and does a statistical analysis to proof that there is a real trend, but I think anybody who looks at the raw data will agree that SGPS indeed holds an edge longer, according to his tests. However, as he also points out, there are some differences between the geometry of the two tested blades, even though he tried to keep the differences small. The ZDP tested was the Jess Horn sprint run.

[Zac]

Theoretically, isnt M4 supposed to hold a better edge than both?

[zenheretic]

Which one rusts less?

[224477]

Very cool link, thanks for sharing Franco :)

I am glad that according to the test the ZDP 189 seems to be the winner :) :) :)

[The Deacon]

I got quite a chuckle out of it. :rolleyes: I think any statistician would be ROFLTAO. The "test" is a comparison of a single knife of each type, each of which was not only resharped, but had its edge geometry modified, prior to testing. Said modification appears to have favored one of the knives as the final angles produced were considerably different. So we have conclusions and graphs based on what has to be considered both statistically insignificant and intentionally biased sample data. :eek:

That's the problem with these tests. Even a manufacturer with fairly deep pockets could not afford to purchase enough of a competitor's product, and allocate enough of their own, to run one that would be meaningful.

[druid]

http://www.fallkniven.com/us-u2.htmse

[walderdackel]

What i would like to know...

The question spooking around in my mind is that heat is not good for any steel because it will ruin the heat-treat.
But if i cut cardboard (i dislike doing it and use only old beaters for that) the edge can get pretty hot.
What does that heat do to the edge???

Mr.Stamps test is pretty interesting to read, but isnt it true that even if you test 2 the same knives (U2 vs U2 for example) you will get different results because of..**** i lost the english word..production clustering??? (plz correct if you know what i mean).
So if you test the Jess Horn vs another U2 the results may be different again.
Anyways, if i take 2 formula one racingcars...12 Hp more or less doesnt make a difference huh :D

Regards

[druid]

to put it in a simple terms is possible let's say that strictly on wear resistance and toughness ZDP189 is a 9.5 is super Gold also a 9.5 is there anything better than either of them are there other steals in the 9.5 category. If so what are they.

[Franco G]

More info:

druid, the correct address is
http://www.fallkniven.com/us-u2.htm

I got the U2 folder quickly after it appeared. It is one of the three non-Spyderco folders I use (the others are BM 710 with M2 steel and SOG X-42 with BG-42 steel). The U2 I own is a wonderfull knife, the SGPS steel, hardened to HRC 62, is fantastic with incredible edge retention. An excellent cutter (something like a smaller ZDP Caly jr.).

JD Spydo, about your question:

Fallkniven has a knife I want which is called the "THOR" and it has laminated VG-10 which I have heard is great. But please do tell us more

I do not own a THOR, but I heard only good things about it. I own a F1 with laminated VG-10. It is really an excellent (small) fixed survival knife (officially used by Swedish military pilots, and by US Navy and US Marines pilots). A laminated blade 420J2/VG-10/420J2 is significantly tougher then a compact VG-10.
A U2 also has a laminated blade 420J2/SGPS/420J2.

HoB, your claim

Well, bottom line really is that Cliff found on cardboard (lots of it) that SGPS actually holds an edge longer than ZDP-189.

is correct. That is confusing IMO. I would expect that steel with more Carbon (3%), and hardened to HRC 65 (ZDP-189), should have a better edge retention then SGPS.

Franco


Franco

[HoB]

The statistics simply are applied to the data points taken during the progression of the test and those are a fair number, enough to do some statistics on without anybody laughing in particular since the test is not random but is framed by the requirement to follow some basic physical principles (a knife shouldn't get sharper during the test). Even under the best and most stingent conditions it will reveal how these particular two knives compare against each other, not how U2s and Jess Horns' in general compare against each other. But this should be pretty clear to anyone who knows something about knives.
As to the edge geometry, yes true both were heavily modified, but as Cliff pointed out a long time ago, you get much quicker and stronger performance separation at lower edge angles than any factory usually runs them. But if they were tested bot at the factory angles the geometry would still have been different so either way you are testing blades with different geometries. Yes it is very true that if the blade geometry is not identical, edgeholding is very difficult to compare, but not only has Cliff pointed that out, but he has shown that himself in prior test were CRK S30V was outperformed by H1 and the Byrd steel on cardboard at very low angles. Something that you wouldn't nessessarily expect. If you read the test carefully, you will see that he himself cautioned against just reading the numbers. Clearly, this test only shows that knife A with steel a and geometry alpha had a higher edge retention than knife B with steel b and geometry beta and NOT that SGPS is better or hold an edge longer than ZDP-189. But isn't that still an interesting result? If the reader's conclusion based on this result is that he should sell all his ZDP knives and only buy SGPS knives from now on then he is to be pitied.

I think the real problem with the tests Cliff does is that a lot of people do not read them. All they do is look at the graphs, look at the tables and may and may not look at the conclusion, nothing else and suddenly they say that Cliff claimed such-and-such. Not to mention that about as many people will hate or find laughable everything he says or writes and other people will take everything he writes as gospel, neither way is really smart I think.

[Joe Talmadge]

Agree with HoB. The test is interesting ... whether it has real-world implications to you personally depends on what you do with your knife. Very low angles do change performance game; the S30V vs H1 test shows that easily enough. Added to that is thte fact that the ZDP blade was at double the angle as the SGPS. Interesting results, but may not (in fact, probably don't) apply to the way most users use their knives.

Joe

[thombrogan]

Interesting results, but may not (in fact, probably don't) apply to the way most users use their knives.

What if the users have been reading your sharpening FAQ and Juranitch's polemics?

Like I did?

[Cliff Stamp]

The question spooking around in my mind is that heat is not good for any steel because it will ruin the heat-treat.But if i cut cardboard (i dislike doing it and use only old beaters for that) the edge can get pretty hot.What does that heat do to the edge?

To overheat an edge you need to exceed the tempering temperature, or hold it there for a long time (like a day). In general most steels are tempered above 325F which means the blade would have to be about 50% hotter than boiling water when cutting up the cardboard to have an effect. A more significant problem is the faster you cut with a blade the faster it will blunt because the impacts and forces on a blade grow very quickly with increasing speeds.

...but isnt it true that even if you test 2 the same knives (U2 vs U2 for example) you will get different results because of..**** i lost the english word..production clustering?

Yes, in the first reference links in the above thread I discussed this as I took four S30V blades and three ZDP-189 blades and showed the individual results cutting cardboard plus the average of each steel. The full details can be seen here :

http://www.physics.mun.ca/~sstamp/knive ... #cardboard

The sample sizes are small, but there are statistics (t-test) which are designed to work with samples of 2 and above to allow inferences on the population. It actually isn't unreasonable to publish with samples that small, you have to consider what you know about the population variance. You also have to look at other data which effectively increases the size of the subset.

That is confusing IMO. I would expect that steel with more Carbon (3%), and hardened to HRC 65 (ZDP-189), should have a better edge retention then SGPS.

So did I, that is why I did it twice and repeated it so heavily in the second trial. As I noted I think it has to be due to the more acute edge and I postulated that this could be due to a decrease in localized strain in the cardboard around the edge. I intend to check this by comparing what happens to a blade as I thin it progressively, while keeping the actual edge angle which is blunting the same. I also intend to look at the push cutting edge retention on other media like carving hardwoods as I suspect the performance won't be identical.

... is there anything better than either of them ...

First off all I would really caution against over simplification, however if you constrain the cutting to long wear slicing, then there are steels I would expect to offer higher performance such as HSS P/M which go up to 72 HRC and have a massive carbide volume. These however are very expensive and difficult to heat treat and have fairly dramatic negatives.

Clearly, this test only shows that knife A with steel a and geometry alpha had a higher edge retention than knife B with steel b and geometry beta and NOT that SGPS is better or hold an edge longer than ZDP-189.

Exactly right.

Not to mention that about as many people will hate or find laughable everything he says or writes and other people will take everything he writes as gospel, neither way is really smart I think.

No, respecting someone's opinion is one thing, accepting what they say as gospel is another. If you have to do one of these things then do the first one. I have no desire to be the leader of a mindless cult.

"The one unforgivable sin, the offence against one's own integrity, is to accept anything at all simply on authority -- Maureen Johnson Long"

What if the users have been reading your sharpening FAQ and Juranitch's polemics?

Those people are stoned with highly polished stainless steel convex rocks.

-Cliff

[Joe Talmadge]

I have no desire to be the leader of a mindless cult.

Well that's disappointing. I was hoping to be appointed high poobah of the Cliffite temple of CA. Assume I can return the fake beards I'd rented for the rituals.

:)

Joe