Some Rockwell results (Is my ZDP Endura a softie?)

gunmike1

gunmike1

Joined
Dec 9, 2005
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I had most of my Spydercos Rockwell tested, and all came pretty much where they were advertised except a couple. First off, my S30V knives, the Manix and Native, both came in at 58 RC. I have been very happy with the edge the Manix takes and holds, but a big part of me wants to see what it would do at 60 RC with a Phil Wilson re heat treat. Then again, it has served me so well as is it makes me think "if it ain't broke don't fix it". Next up, all of my VG-10 knives came in at 59 RC, except for the R2 which came in at 58 RC. All perform very similar, though the R2 seems to just the slightest bit want to burr more than the others. I would guess most of the time it is my technique more than the measly 1 RC difference, and the ergos and grind on that knife make it my favorite VG-10 Spyderco. Next up were the Byrds. The G-10 Cara Cara got 58 RC, while a Krein reground Meadowlark with a .004" edge got 60 RC. That Meadowlark takes a really good edge, and the steel composition at that hardness would seem to be a good reason why it takes such a good, acute edge.

Last up was my solid ZDP Endura. I literally got it and shipped it off within a day for the testing, so I have never used it. It wasn't Spyderco sharp from the factory, as it was a bit burred, but that doesn't bother me much as it is due for a reprofile and sharpening anyway. It only came out at 63 RC (did I really just say ONLY 63 RC? Am I nuts?), while I was hoping for more like the 65 RC that the factory shoots for. At least I think I remember reading that they shoot for 65 RC. Maybe they softened it up for the long, solid ZDP blade of the Endura. If I never got it tested I probably wouldn't know the difference between what it is and 65 RC, but you know how that voice in your head is always telling you something can be better than it is. I'll have to sharpen it and use it and see how it does. I'm planning on sending it off to Tom Krein to get a full flat grind to a .010" edge put on it for more cutting ability, hopefully it performs up to snuff compared to my other ZDP knives (I couldn't RC test the other ZDP knives because they are sandwiched with 420J2).

Mike
 
Not that I'm an expert or anything, but I thought I may heard that most of the zdp-189/420 combos are resting at about 67...makes since with the 420 samich!:)
 
I have been thinking that I would put my own custom ZDP knives into service at RC 63-64. I think this would allow them to be nice and thin and tough...

I may be deranged, but I think RC 63 will still perform very well!!:cool:

Tom
 
64, William Henry advertises 67. For mass produced knives, a one point diff is good. the margin of error for some test apparatus is +/- a point to begin with.
 
Tom Krein said:
I have been thinking that I would put my own custom ZDP knives into service at RC 63-64. I think this would allow them to be nice and thin and tough...

I may be deranged, but I think RC 63 will still perform very well!!:cool:

Tom
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I'm thinking it will be perform just fine, I just want it to perform like my other ZDP knives, which may be the same hardness anyway. I'd be very interested in seeing what your own stuff in ZDP would look like! By the way, I was about to call you about regrinding this knife and another one, I was hoping to ship them off next week. Do you mind going full flat grind with the Endura and flattening the spine into a splinter picker tip similar to the Spyderco Milatary?

Mike
 
In production knives a 'normal' Rc value is meant roughly +/- 1. Good companies (including Spyderco) should have +/- 0.5, and it is mostly a case.

So, Rc 65 means at best the range Rc 64-66. Rc 63 is one point bellow. It is a question of HT (heat treat.). It is obviously clear why people adore Paul Bos - Paul is able to get maximum even with 'ordinary' steels such as 420HC.

IMO Spyderco should test Rc hardness at least for high end knives (say, starting with MSRP $200). I would appreciate to have Rc hardness written on a blade, rather than a 'childish' Earth. All other discussion is a question of QC. Some production knives companies, e.g., Puma, check every knife and through away anything with Rc lower then 57 (their steels are mosltly a German equivalent of 420, 440A ... 440C). Shouldn't Spyderco do the same? I think so. And a small point (coming from the Rc testing in the blade is also a sign of quality.

A good QC could avoid unpleasant surprises (remember Simona's low Rc measurement?).

I would also prefer TazKristi starts a threads with 'Guess what is Rc hardness of my CPM D2 Millie...' instead of childish 'Guess where am I now...'

Anything said by me is said bona fide, no offense meant. I hope, Sal, being himself a steel junky too, would understand that for steel junky (as me) it is not the same thing to own an incredibly perfect ZDP-189 CF Caly 3 at Rc 65 or 'only' at Rc 63.

Franco
 
Franco G said:
IMO Spyderco should test Rc hardness at least for high end knives (say, starting with MSRP $200).

Franco
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Considering that the vast majority of Spyderco knives MSRP for less then $200, and sell for much less then that, I don't think that it would change much.

Also, wouldn't it cause a nice little price increase? I'd rather keep it the way it is.
 
I would not mind having a RC dimple on a blade, but I don't know that it is necessary on each and every blade. I do think that multiple random examples of each and every heat treat should be tested.

I personally would rather not have a RC level printed on my blades. I prefer not to have a bunch written on the blades. I belong to the less is more club when it comes to writting on knives and guns!

Just my 2 cents worth.

Tom
 
I wouldn’t worry about this for few reasons.
I recently was looking for a new hardness tester for my company and find out that on US market accuracy of hardness testers is +/- 1 point, so if your measurement is 63 it can be really 64, even if testing performed correctly (some measurement error can be present as well).
When heat treatment performed on the large lots of material, there is some variation in hardness from piece to piece (and if pieces large enough, variation can be present within the same piece). My company is dealing with several heat-treating suppliers and usually they asking to allow at least four point range.
I am not sure that it will be possible to see the difference in performance of 63 HRC and 65 HRC blades in normal use.
 
Franco G said:
All other discussion is a question of QC. Some production knives companies, e.g., Puma, check every knife and through away anything with Rc lower then 57 (their steels are mosltly a German equivalent of 420, 440A ... 440C). Shouldn't Spyderco do the same?

Franco
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No.
I am quality professional, and for me 100% inspection in production looks like indication of not capable process (did you say Puma???). Plus I would hate to have visible indent and cost increase.
Also to check hardness on laminated blades without destruction will be really tricky
 
bh49 said:
I wouldn’t worry about this for few reasons.
I recently was looking for a new hardness tester for my company and find out that on US market accuracy of hardness testers is +/- 1 point, so if your measurement is 63 it can be really 64, even if testing performed correctly (some measurement error can be present as well).
When heat treatment performed on the large lots of material, there is some variation in hardness from piece to piece (and if pieces large enough, variation can be present within the same piece). My company is dealing with several heat-treating suppliers and usually they asking to allow at least four point range.
I am not sure that it will be possible to see the difference in performance of 63 HRC and 65 HRC blades in normal use.
Click to expand...


First, the testing was done by a person very well known for his knives & heat treatments, and he uses calibrated equipment that he is very experienced at using, so I am very sure that these results are as accurate as possible on a Rockwell testing machine. Yes, they could be off by whatever the error in the machine is, but I would guess it is in the .5 RC range, but maybe it is 1 point. Your point still stands as valid about the real world difference of 63 RC vs. 65 RC, and the uneveness of batch heat treats. I would expect to see some variation among the blades in the same batch, and that is why I had the knives tested in the first place, to see for sure what the blades are at. While in theory the harder blade is preferable, I know two other non-Spydercos that I had tested had the more burr prone blade come out 1 point harder than the blade that takes a better edge. With the complexity of heat treating, which I know next to nothing about, I am thinking it is possible to get one ZDP blade at 65 RC that doesn't perform for crap, and another at 63 that performs great, depending on the heat they reached, how quickly and what cooling method was used, or even what part of the oven they were in. Again, this is just speculation on my part speaking out of ignorance of the heat treating process, but it is the thoughts going through my head. I was about positive my Manix would be at least 59, and probably 60 based on how it doesn't burr when sharpening, takes a great edge, and holds it well, so this Endura may well make me extremely happy like the Manix does with it's performance. So I may not see any difference, but then again I may, as others have had very positive reports of Phil Wilson's re heat treats of S30V by a couple Rockwell points making a noticeable difference in performance. The bottom line is I'll have to sharpen and use the knife and find out how it performs for me. With a Tom Krein regrind I'm sure it will work out very well for me, but we'll have to see. I guess the bottom line is I should have used the knife before RC testing it to avoid any preconceptions of how the knife will perform, but since I was sending off 11 others I threw it in with the rest of the bunch. Knives are a hobby to me, all this RC testing just makes it more complicated, but I guess the wanna be scientist and knife knut in me wants to know the down and dirty details on all of my blades. Off to the hones to see if I can throw an edge on it and to cut some things (if my daughter ever takes a nap)!

Mike
 
bh49 said:
No.
I am quality professional, and for me 100% inspection in production looks like indication of not capable process (did you say Puma???). Plus I would hate to have visible indent and cost increase.
Also to check hardness on laminated blades without destruction will be really tricky
Click to expand...

Hi, bh49,

this I just copy from Puma's official FAQ:

ť Why is there a tiny hole in the blade of my Puma knife?
This is the so-called "Rockwell point". All puma knife is checked on its rockwell hardness according to the system Rockwell C . For this a diamond top is pressed into the blade under a fixed burden and the penetration depth is measured. The stated value determines the hardness of the steel.
Click to expand...

It is not so expensive. Better pay a few bucks more than getting a lemon.

Franco
 
Factory tested RC was something I though only a few higher end makers did till I was showed these on another forum. My China made Steel Warrior Toothpick has a RC test dimple and had a sticker on the blade pointing to it and had RC 57-59 printed on it. It was an 8 some odd dollar knife. Got it here. http://www.collectorknives.net/work-knives.html#SteelWarrior
For a sub ten dollar knife, it is extremely well built and to have been RC tested from the factory says a little something about them. Regardless of where its made, it is a NICE knife, almost irresistible for the price IMO. I think I would accept a test dimple on some of my blades. Perhaps dead center of the Spyderco totem? If thats possible?
 
thombrogan said:
Guessing the tang as that's where it's flat. Knowing Gunmike1's friend, I know it's the tang.
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You are correct, sir! I also reprofiled the ZDP Endura to 10 per side, brought it from DMT XX coarse, DMT Fine, Norton 1000 grit, up to Norton 8000 grit, then finished with 1 micron and .3 micron lapping film on glass (thanks for the films, Thom). It forms edges cleanly without much burring, if any, to speak of, and whittles hair decently with the current sharpening job. I need to cut with it now, but I really can't wait until Mr. Krein does his magic on it. I have to once again praise the DMT XX Coarse, it didn't take much time at all to go from about 15 per side to 10 per side on ZDP 189, that stone just rocks! For reference, I sharpened my Manix the same, except on a 15 degree microbevel, and it whittles hair noticeably better, but the abrasives and the fact it was my first time sharpening the Endura might account for the difference. Either way it gets pretty darn sharp, even with my primitive skills.


Mike
 
Franco G said:
It is not so expensive. Better pay a few bucks more than getting a lemon.

Franco
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Hi Franco,
If this testing would be performed in US, it would be as you said a few bucks, which I would like to avoid and also it wouldn’t guarantee from getting a lemon. 100% inspection is not 100% effective, but something like 97%. So if in the lot of 1000 pieces somebody has 100 defective, only 97 will be detected and 3 will go to customer. The only way to avoid defective product is to develop capable process and monitor it through sampling and analysis. Sorry if this explanation too long and boring.

Roman
 
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