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For Cliff Stamp: sharpening VG10
- Thread starter daberti
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Cliff Stamp
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I generally use between 10-15 degrees as a finishing edge on such blades, it is freehand and the angle falls inbetween there depending on the knife. I have no problems outside of cutting metals. 600 DMT is a general nice working finish because it isn't so coarse that it really slows down push cutting and it retains a nice aggression.
-Cliff
-Cliff
Cliff Stamp
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It has been a few years since I used the Edge Pro, however from memory the stones get very fine very fast. I think the white stone after the coarse one would be similar. In general after using a knife you will either notice one of two things, the knife is slipping too much on slicing or you are seeing too much resistance when directly pushing through materials. You decrease the grit for the former and increase it for the latter. In both cases, lowering the relief grind for the edge helps.
-Cliff
-Cliff
Got it. Thanks
Cliff, I recall you told me that under a certain edge angle I should go polished anyway.
I don't remember if it was 15° per side or other.
Could you please give me a rule of thumb?
Thanks
Cliff Stamp
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Yes, the same finish is inherently much more aggressive when the angle is reduced. It is basically proportional to angle, so if you cut the angle in half the edge gets twice as rough at the same finish, meaning the size of the teeth produced. There also tends to be little need to slice at really low angles due to the very high cutting ability and the difference in force between a slice and a push cut starts to get very small.
However there is a complication in that some steels just break apart at low angles. Johnston described this back on rec.knives in the 90's and was severely critical of ATS-34 because it would not hold or even take a high polish when the angle was acute (< 10) and more recently Landes studied the subject in in great detail and found the same thing for the P/M version and other steels like S60V.
In short, as you reduce the angle you get the same aggression at a higher grit which tends to make higher grits more favorable at lower angles. Moving below 15 makes this noticable and under 10 most really coarse stones tear visible pieces out the edges. However if the steel is really coarse then you might as well leave the edge at 600 DMT or medium Spyderco because it won't hold a high polish anyway.
-Cliff
That is to say that leaving my P1 at 18/21 per side should need 600DMT (actually I went 320 EdgePro).
Should I go 15 than I should use 1200DMT (600Edge Pro or even higher)
With S90V a polished edge could never been reached, on the other hand.
Right?
Thanks
Cliff Stamp
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Yes, those are the generally the type of choices made. The exact grit which is optimal will depend on what you cut and how.
-Cliff
-Cliff
I've left S30V alone for the while. I learned that it needs HRC61 to minimize burrs and to have a real step up in edge holding. Also I've learned that CPM steels should be triple tempered and cryoed to perform at their very best.
Thus ain't no use in buying production S30V knives at 58-60HRC, for they'll give me only minimal advantages over a Vg10@59HRC blade at a far higher price tag.
More than a friend of mine bought an expensive folder (no brand names) made of S30V just to have it re-heat treated.
Should they had gone straight to a custom with even S90V steel the bill would have been far smaller ;-)
Cliff Stamp
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Yes and likely then they could have got the blade customized in other ways as well. Hopefully as more users become aware of what steels can do and what is required of them for optimal performance, more pressure will be put on manufacturers to make such blades.
I'd agree pretty strongly with the points you made regarding steel. You tend to need a very high hardness to see an improvement in edge holding in general, assuming you are speaking of mainly light cutting which isn't impact sensitive.
-Cliff
And the manifacturer above decided to make a 5" and 7" fighter/allround/ heavy duty knife using S30V, keeping HRC at ridiculous levels (but prices at custom level at least here in Italy). You reviewed that knife as well as the folder and I absolutely agree with your results.
In other terms: if you buy a Porsche you should be aware of not being properly in the list for the economy-run prize and behave accordingly.
Here we should make some exceptions though.
Finer grained structure, wear resistance, material to be cut do come into account.
I.e.: I've some doubts that S30V edge holding (ceteribus paribus) @61HRC would overtake S90V's one . Even with the latter run at 59.
As I strongly disagree with ZDP189 approach. I've had the Caly and WH B12FT. Caly run @65 and WH @67. Using my F4 daily on cardboard, carpets and other abrasive media, proved to me that S90V even if far lower on HRC, keeps the edge better (I reprofiled to 20° per side all of 3 knives). Ok ok, edge profile and geometry....I do agree, yet I'd never take a ZDP medium-to heavy duty folder with me on backpacking .
On the other hand it stands literature about heat treating these supersteels.
There is a bunch about CPM, but not about ZDP.
I'd like to make a philosophical point then.
CPM made S90V as an improvement over S60V, and actually it is.
You know that if your knife is S90V @>58 then it will hold an edge for an age, with very good toughness and stain resistance and supreme wear resistance.
Under 57 it wouldn't simply cut and over 61 is nearly a daredevil. Its heat treatment requirements are very strict and leave no time to errors or improvisation.
But many brand names asked for a CPM stainless steel capable of bringing benefits over the average joes of other steels, without requiring such attention and costy manifacturing/working processes. Thus we had S30V.
Heat treatable by all, workable by all. This brought about a great variety of hassles: edge chipping, hardness at sh**ty levels, shamy edge holding and more...
Normally in free market if something is available to all (raw materials and know how to make them perform at their best), competition would bring the end users the best value added finished product possible, but here proper heat treatment is now left to manifacturers good will, rather than imposed by steel's intrinsic requirements. Yet S30V on your blade will justify an increase of selling price.
Thus I would call S30V the "Unethical CPM stainless steel"
Cheers
Cliff Stamp
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The wear resistance of S90 would be much higher even at the lower hardness and thus I'd expect it to do better in extended comparisons. If you reduced the angles and examined the ability to keep a high sharpness I'd expect the S30V blade to be ahead, but you would be looking at a small amount, much less than the advantange S90V would have in the long term.
That is interesting, there isn't a lot about those steels compared. Spyderco ranks them the same in CATRA tests and both are well above S30V which you would expect for that type of work. About how much cutting do you do before you resharpen, how dull do the blades get. Do you find the S90V has a slight advantage or is it actually a multiple amount of material cut? If you were so inclined I would be interested in the relative performance at 15 degrees per side.
Indeed, this is part of the myth of "superior" steels and likely the primary reason why they are used simply because they can sell. I would be really curious to see how many people who promote such steels as superior would actually be able to tell them apart in unmarked blades. The introduction of S30V was exactly as you describe, S90V was too hard to grind and heat treat so performance was traded for ease of manufacturing. However this was quickly overshadowed by the extravagent claims for S30V and S90V was forgotton.
I'd be curious if S90V was the limit for that composition, how would it behave with 12.5 or 15% vanadium. At what point would the edge not have enough stability to offer functional levels of sharpness.
-Cliff
Yes, I do agree but we both know that working with REALLY low angles ain't a great idea with high alloyed steels, at least if you wish to keep them from chipping when going for a week long trekking session ;-)
I didn't count the number of cuts for I've a repetitive cutting weekly need. But I never let the blades really go dull: i.e. at the point of needing a re-sharpening instead of a touch-up. Never went below 15 on the other side. This would be easily done on the two ZDP blades, but due to high V contents and the very geometry of F4, this would have taken TiAlN coating off and would have required lowering the entire relief. No way on a 620EUR blade :-(
Never took WH with me in the wilderness, yet I took Caly and pitting on the ZDP non edge portion happens with way much easier than with S90V (F4 by Kevin Wilkins).
To be honest I don't have literature to say how this ZDP has been heat treated, maybe Sal can help us, but for sure it has been in Japan, thus I've to say "at state of the art" level. And being at 65, more stainless than at 67.
S90V is tougher, more stain resistant and wear resistant. Keeps the edge better for the above mentioned tasks. Probably Spyderco uses a "weighted" CATRA edge retention test? Sal, please get in and tell us.
ZDP can be resharpened way more easier, but this represents o no-problem to me.
Where does it stand the frontier actually? Probably it is S125V.
To my knowledge the only one who sells S125V made blades is Farid
http://www.faridknives.com/index.html.html
My understanding is that it should be on same toughness level as ZDP or even better, with edge holding ranging from 1.75x (worst case) to 2X (average case, based on my cutting needs above) the one of ZDP...
Indeed, this is part of the myth of "superior" steels and likely the primary reason why they are used simply because they can sell. I would be really curious to see how many people who promote such steels as superior would actually be able to tell them apart in unmarked blades. The introduction of S30V was exactly as you describe, S90V was too hard to grind and heat treat so performance was traded for ease of manufacturing. However this was quickly overshadowed by the extravagent claims for S30V and S90V was forgotton.
I'd be curious if S90V was the limit for that composition, how would it behave with 12.5 or 15% vanadium. At what point would the edge not have enough stability to offer functional levels of sharpness.
-Cliff[/QUOTE]
Cliff Stamp
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Yeah, this isn't unexpected as the massive carbon content would seem to have to tie up a lot of the chromium as carbides.
Generally, making a steel softer tends to reduce corrosion resistance.
CATRA curves are non-linear (as are all blunting responces) which mean where you compare the blades will change the results. I'd like to see the full curves. But it is also very true that what you cut and how, and how you sharpen, will also effect edge retention. What would be interesting is that are you seeing higher relative performance for S90V than Spyderco or lower relative performance for ZDP-189.
Yeah he uses some really high alloy steels, but I would not want them on the blades he uses them for :
http://www.faridknives.com/T-9000.htm.htm
That type of knife I would want in 12C27m not S90V.
This leads me to the conclusion that ZDP way is pretty meaningless to me.
Yes, and this I was trying to say: even when ZDP is left softer it has very poor corrosion resistance if compared with S90V.
But don't forget the cutting environment I scored the result from!
12C27Modified? Didn't you mean to say 13C26 by chance?
Anyway probably it should have been offered the CPM3V option or the CPM154.
BTW: I do hate Tanto point style.
This introduces a thought of mine.
We've said that S30V deserves better "care" to give its best.
CPM154 edge retention compared to S30V is 150 to 210, per Phil Wilson data (mainly manila rope cutting).
1)What if cutting environment would have been more weighted? Probably we would have found the two way closer.
One step further: 2)bringing 154CM to 61 has been a nightmare for the smiths, and in production knives you'll see typicall 58-60, just as S30V.
But it is pretty simple to bring to 61 CPM154 instead, with less expense for the producers.
Lets put the whole thing together: would the CPM154 production treated cut and hold the edge equal than prod. treated S30V for most tasks? Would it have less chipping problems?
Yes, for sure IMHO.
In the end those using S30V improperly heat treated would stop doing so, for their own convenience, and S30V would be implemented only by people seriously committed to bring it at its very best.
Thus I'd invite you to re-think your position about CPM154, which was skeptical if I got it right
Note: CPM should avoid making a bare CPM grade clone of 154CM, for there is already RWL34 on the market. These guys should seriously consider throwing some Moly in the trash and putting some Cobalt in instead, for added resiliency.
This way we should have a particle metallurgy VG10/N690, with all of the benefits for edge-holding demanding implementations that don't want to sacrifice toughness.
Cliff Stamp
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No, on a larger knife I would drop back to 12C27M, 13C26 is more for light use knives. But of course I was thinking if it had to be stainless, without that constraint I would simply pick a low alloy tool steel designed for high shock.
I am not sure what you mean exactly by weighted. If you mean harder on the knives, more shock and thus more sensitive to toughness, then yes you could easily change the results. Similar if the cutting was done wet, or how long the cutting was done. If for example if you cut until the blades stopped being able to slice newsprint the difference would actually be much greater. If you stopped when the blades could no longer push cut paper, then the results would be much closer together. It would also change if you switched to a push cut, and will further be influenced by which grit you use.
The 60 HRC thing is more simply because that is what people think makes a "good" hardness. Benchmade ran their ATS-34 above 60 HRC as did a number of custom knifemakers like Harley who had small skinners at 62 HRC.
To be frank, I think most of the arguements to explain the chipping problems of S30V are excuses which rely on the sheep factor of people to not be critical of what they are told. S30V, according to Barber, was designed specifically to enable knifemakers to do the heat treating rather than rely on commercial equipment.
P/M's are also in general more consistent and easier to heat treat (at a given composition) than ingot steels. S30v was even promoted for ease of heat treating over 440C for example and who has problems with that steel and complains it is too demanding to harden. So it seems really odd to try to explain the problems reported with S30V as it being really demanding to heat treat.
The main problem with S30V was that it was constantly and heavily promoted for high toughness this then obviously lead to people being a lot less tolerant of any chipping damage and being a lot more vocal when it happened as well they were also likely to do things a bit more demanding. Then it sort of became in vogue to critize the steel and thus the complaints increased massively in frequency.
Yes but you kind of hope that nobody realizes that because S30V was promoted over RWL34 so it is kind of absurd to now promote the opposite.
There are very likely P/M steels in existance which do exactly that already. However I don't think you could argue that molybdenum has such a detrimental effect on toughness. For example the main difference between 440C and 154CM is a reduction in chromium and an increase in molybdenum and looking at the materials data, and structure of the steel, it pretty much makes a directly better product.
-Cliff
I see.
By weighted I mean "A test able to reproduce a wide enough real world cutting tasks, for the average use the knife was built for".
Yeah. But how about 154CM if compared to VG10 or N690?
The latter have Cobalt and (very little) Vanadium, and less Moly. Their corrosion resistance is superior, as toughness (per my experience) and edge holding.
Cliff said:
I was browsing through a book on hunting knives (the author being a hunter) in the library. This was current up to 154CM/ATS-34, and the author was unable to dissociate the words "premium" and "tough." Now to be fair, premium is sort of vague, able to mean of higher quality (any specific qualities) or higher price. So it would not be a total falsehood if the context with repect to price/wear resistance/ease of heat-treatment/hot-hardness and tougher when compared to 440C. But the inference is of course that it extends to all steels of lower costs.
When I first purchased a S30V Native at the beginning of this year I was certainly expecting, due to the ethusiams created by the forum, not some incremental improvement in some specific qualities but a huge step forward overall. As if copper just met bronze. I think prehaps it is sort of a natural state of thinking, until tempered by experience and education, of which apparently not everyone is exposed to or wants to be exposed to.
Cliff Stamp
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Toughness tends to be an all encompassing term used by makers to speak of many qualities, for example a steel can be tough to grind and by this perspective D2 is a very tough steel. Materials wise this is grindability and toughness means resistance to breaking at high rates of strain, low strain rates are generally characterized by strength.
Indeed, there is a backlash now against people who are citing problems as if they are BS, often by makers or others who have promoted the steel as a defensive reaction who are ignoring the heights to which the steel was promoted. One of the most reasonable promotions of the steel was by Strider who noted early on that it was basically a 5% improvement over ATS-34. This was drowned out by the more dramatic praise. Often what is focused on is just the strengths and not the weak points, a high edge retention in one area for example often tends to be accompanied by a low edge retention in another area because there are many qualities which effect edge retention depending on what you are cutting and how and you can rarely increase all material properties at the same time. It is expected of course for those selling the material to focus on where it improves which is why you should always look to see what they don't present and ask for that. So for example if someone is promoting a steel as being a great edge holding material because it slices rope for a long time then ask them how well does it hold a shaving edge if you push cut cardboard or chop wood, assuming either of these is important.
Yes, that can generally change a lot of things as it bring in many properties. The extended slicing tests tend to be mainly dominated by wear resistance and they are performed at identical geometries which ignores the fact that different steels can take different geometries which effects the results significantly. Johnston noted this on rec.knives years ago in that if you took ATS-34 and 1095 at common obtuse profiles and then compared them at very acute angles you got very different results because 1095 could go much finer due to the smaller carbides.
That would indeed seem to be a more productive direction as Spyderco has compared 154Cm and VG10 and found VG10 to be pretty much a superior blade steel, 154CM isn't a blade steel and VG10 was so designed. The same manufacturer who makes VG10 also makes P/M stainless which are also designed as blade steels.
-Cliff