I need a finer bench stone for soft steels. Maybe Arkansas?

[Squashfan]

That helps a lot,

The Shapton pro are very nice for chisels as are the Chosera/Naniwa Professional stones. It makes it a tough choice because all of them are premium stones. Argued among professionals as to which set is better, and I, a owner of both sets has difficulties deciding which I like more.

As an all inclusive stone that covers the most bases its probably tough to top the Shapton Pro 1500. By itself can be a finishing stone for softer carbon and stainless steels yielding a fine toothy cutting edge that's easily stropped to much higher levels of sharpness if needed. This stone favors carbon steels and tends to clog slightly with stainless.

The 1k Shapton Pro is more like an 800 grit stone and is easily one of the fastest 1k-ish stones I have used. It also stays very flat and wears slooooooooow, though don't get behind in lapping or you will hate life. If you want a powerful 1k this is it. This stone will handle most any steel.

Naniwa Pro/Chosera, if you ever find Zen while sharpening it will likely be with these stones. Plays well with carbon and stainless, better choice on softer steels too. It's tough to swallow the price point of these stones but you will never regret the purchase.

Was going to reply to this earlier but I got side tracked. Sounds like the 1K Naniwa Pro or 1K Shapton Pro is the way to go for me. I want a fast stone that is still fine enough that I can stop after just one stone. A 1k waterstone should be finer than my India.

I stop at Blue Box Home Improvement and picked up a Smith's Arkansas stone. I don't have much of an impression of it yet.

 

[Jason B.]

The 1k Naniwa Professional is much finer than the Norton India, The Naniwa Professional which are the new Chosera stones are a finer grade of stone to begin with, the 1k is more like a 1200 grit while the Shapton Pro 1k is more like an 800 grit stone.

It's a tough choice even from my perspective but in your case I have to say Naniwa Professional.

 

[Benuser]

I treat my soft stainless and soft carbon kitchen knives VERY differently. For the stainless, as others proposed, have the coarsest SiC stone. Use good pressure. Strop and deburr very lightly on a JIS800 or so and you're done.
Soft carbons -- French, vintage Sheffields -- get the same full progression as harder Japanese carbons, up to JIS8k for stropping, deburring and touching up. The edge geometry of course is very different. They are at their best with an inclusive angle of some 50 degree, obtained with a one-sided microbevel of more than 30 degree. Just as with a carbon Opinel.

I'm by far no metallurgical expert, but I guess it's the huge carbides in soft stainless that cause their edge weakness when even somewhat polished.

By the way, IIRC, the Chosera 800 corresponds more or less to JIS1200. A very interesting stone, hard, fast, offering a lot of feedback. Very versatile: you may use it for thinning your carbons as well. Just a bit slower than the Chosera 400, but with less dishing.

 

[Obsessed with Edges]

I treat my soft stainless and soft carbon kitchen knives VERY differently. For the stainless, as others proposed, have the coarsest SiC stone. Use good pressure. Strop and deburr very lightly on a JIS800 or so and you're done.
Soft carbons -- French, vintage Sheffields -- get the same full progression as harder Japanese carbons, up to JIS8k for stropping, deburring and touching up. The edge geometry of course is very different. They are at their best with an inclusive angle of some 50 degree, obtained with a one-sided microbevel of more than 30 degree. Just as with a carbon Opinel.

I'm by far no metallurgical expert, but I guess it's the huge carbides in soft stainless that cause their edge weakness when even somewhat polished.

By the way, IIRC, the Chosera 800 corresponds more or less to JIS1200. A very interesting stone, hard, fast, offering a lot of feedback. Very versatile: you may use it for thinning your carbons as well. Just a bit slower than the Chosera 400, but with less dishing.

The 'soft' stainless types most often found in common kitchen knives won't have enough carbon content to contribute to formation of large carbides (such as chromium carbides, formed by an adequate combination of carbon + chromium). Low carbon content is also what leaves these steels relatively 'soft', as it's the amount of carbon that makes it hardenable by heat treat in the first place. Because there's not enough carbon to form significant chromium carbides, the high chromium in those stainless steels goes almost entirely towards corrosion resistance instead (chromium combines with oxygen to form chromium oxide, which makes it 'stainless').

Contrast the above with steels like D2 and ZDP-189, which have both very high carbon and relatively or very high chromium, large parts of which will combine to form very hard and (sometimes) very large chromium carbides, and the higher carbon will also allow hardening to much higher RC, especially with ZDP-189.

The 'edge weakness' (rolling or plastic deformation, in other words) in softer steels is due more to the low RC, which is due (usually) to lower carbon content and it's limiting effect on hardness (RC). Carbides contribute more to abrasion resistance, which is independent of hardness of the steel itself.


David

 

[Benuser]

Thanks, David. The soft stainless I've in mind (Wüsthof e.a.) do form chomium carbides as far as I understand, that's what makes them so terribly abrasion resistant. Am I wrong?
How do you explain the soft carbons to hold a highly polished edge, while the comparably soft stainless won't?

 

[Obsessed with Edges]

Thanks, David. The soft stainless I've in mind (Wüsthof e.a.) do form chomium carbides as far as I understand, that's what makes them so terribly abrasion resistant. Am I wrong?
How do you explain the soft carbons to hold a highly polished edge, while the comparably soft stainless won't?

There'll always be some small amount of chromium carbide in stainless steels. But the amount present in Wüsthof and similar stainless is insignificant, and whatever carbides are there are usually very small and widely dispersed.

'Soft' carbon steels usually contain significantly more carbon than 'soft' stainless steels, which is why they hold an edge better, though the description of 'soft' is misleading and, in this case, more a reference to carbon steel's relatively low abrasion resistance, due to minimal carbide content. They usually have virtually no chromium, or just miniscule amounts of it (as with 'CV' steel), to form any chromium carbides at all. Compare a steel like 1095, which contains ~1% carbon by volume, versus a steel like Wüsthof's 'X50CrMoV15' stainless, with 0.5% carbon (50% LESS than 1095, by direct comparison). This means the 1095 is more capable of holding a finely-polished edge, because higher carbon contributes to edge-holding, i.e. resistance to rolling or denting, but it doesn't have the abrasion resistance afforded by harder carbides, which otherwise would add resistance to abrasive wear. 1095 has no chromium at all; therefore it can't have chromium carbides. The higher carbon content in 1095 is what makes it more capable of holding edges better than a relatively lower-carbon stainless steel, assuming the heat treat takes advantage of it.


David

 

[Jason B.]

German steels have chromium to make it stainless which forms chromium carbides but the steel itself is VERY soft and not at all wear resistant. With a common Rockwell in a the mid 50's and not much in the way of hard carbide formation German steels don't pose much of a challenge in sharpening.

Apples to oranges with carbon and stainless, carbon always takes a better edge, though I can't expain why.

Also, 50 inclusive is a bit on the extreme side of obtuse. Cutting edges just don't do well at such angles.

Why such a complex bevel geometry? A single sided Microbevel does not fit the norm.

 

[Jason B.]

Good explanation David :thumbup:

 

[BluntCut MetalWorks]

Low RC stainless steel cutlery (0.5-0.7%C) often cited as not having enough carbon to fully harden steel matrix and form carbide. This technically is incorrect.

High Cr steels(Nitrogen less) requires about 0.45-0.5%C to fully harden the matrix, any excess carbon will form carbide with mostly Cr. In most cases, bad ht (harden temperature too high) locked so much Carbon in the form of retained austenite(RA), prevent fully harden matrix and virtually nothing for alloying/carbide with = lousy gummy/soft edge roll-over cutleries. If a ss edge can't take grit higher than 320+, most likely due to this bad ht. While too-low of harden temperature, too much carbon can be locked up in carbide form (M6C3, M23C6), thus not enough carbon to fully harden the matrix.

In general, it takes less Carbon to full harden a stainless steel matrix than carbon steels.

 

[Squashfan]

The 1k Naniwa Professional is much finer than the Norton India, The Naniwa Professional which are the new Chosera stones are a finer grade of stone to begin with, the 1k is more like a 1200 grit while the Shapton Pro 1k is more like an 800 grit stone.

It's a tough choice even from my perspective but in your case I have to say Naniwa Professional.

I had a reply that I thought I posted. Anyway, I agree with you. I think the Naniwa Pro is the right choice for me. It should be fine enough to do soft steels well but still cut fast enough to work and finish steels like 154CM, VG-10 etc.

Been trying a smith's arkansas stone that I bought at Big Blue Home Improvement. If I do my work on the preceding stone, I really like it. Is it necessary? No. Is it nice? Yes.