(Another) question about sharpening gears...

[benichka]

Hello everyone!
I jumped in the “freehand sharpening train” probably 5 years ago, buying a Shun and a stone (from the same brand, a 1000/6000 combo), trying to sharpen without real knowledge… The result was 2 or 3 knives wasted (not the Shun, but small Sabatier-like ones) and a stone very worn. Few years later (yes, years), I learned about the “lapping” thing, so I bought a lapping stone! And lapped mine (it was SO dished… Didn’t take a picture but trust me, you didn’t want to see).
I then found 2 major source of sharpening videos: Richard Blaine’s channel and Japanese Knife Imports’.
As I only had one Japanese knife (and 3 or 4 “Western” ones), I mostly watched Richard Blaine’s. Apparently the guy’s a joke on this forum To be honest I learned a lot of things with his channel, I even learned how to have a decent edge on my knives.
So, in order to have a decent kit (remember, I only had one stone: a Kai 1000/6000), I gradually bought a kit of DMT bench stones (DMT DuoSharp W250CXNB and DMT DuoSharp W250EFNB – so basically 220 / 325 and 600 / 1200 grit or 60µm / 45µm and 25µm / 9µm) and last month a Spyderco 302F (ceramic – fine) and 302UF (ceramic – ultra fine).
I didn’t have the chance to test them well, but I managed to have a really sharp edge with this combo (only tested it on 2 knives so far).
Few days ago I discover this forum: and apparently, diamonds stone are “too harsh” for the blade, honing steel are the last resort and should be avoided… In a nutshell: go stone all the way! And eventually go strop in the end
My question is: are diamond plates so bad? Is it bad for my knives if I begin with 600 / 1200 diamond and then go with the ceramic or 6000 stone?
What’s the difference with a “full stone” process?
Other question: is it relevant to use the 6000 after the “ultra fine” ceramic? Or do I need to pass by an intermediate stone, say a 3000? I didn’t see a lot of threads regarding ceramic plates, so I’m wondering what you guys are thinking about those…
Last question! Apart from Mister Blaine, do you know any videos for sharpening Western knives? Or do you sharpen them like the Japanese ones?
Thank you and have a good day!

 

[daveb]

Welcome to the forum.

I started with the duo stones on hunting knives and still use them for that purpose. I also still use them to start when sharpening friend's Germans and other knives, usually using the XC/C plate then moving to a med stone. They're light, transport well, seemingly last forever and relatively inexpensive. Note that the grit system they use is different than the grit system for stones. A translation table is available on the DMT site.

They can be used on kitcen knives but the down side is they'll scratch hell out of your knives and there is little to no tactile feedback. Most here enjoy sharpening and so it is not a tool frequently used. If you want to continue with them Marko (a vendor here) offers a XXF plate for finishing the edges.

Good luck.

 

[psfred]

Diamond plates are not "horrible", and I use them for many things (restoring badly worn wood plane blades is one where they shine), but I don't recommend them for Japanese knives for several reasons.

First, as noted by daveb, they will scratch the bejesus out of your knives if you slip while sharpening -- diamonds tend to the coarse size due to the means of attaching them to the plates, and are VERY hard. Even minor contact with make deep scratches. If this doesn't bother you, no foul.

More importantly, though, with very hard (and hence somewhat brittle) steel as is used in Japanese style knives, coarse diamond abrasives can produce not just deep scratches, but since they do NOT roll or wear short of being ripped out of the plating, can cause local pressures at the contact point with the steel off that exceed the strength of the steel. This produces micro-cracks that rapidly turn into micro-chips in the edge. Probably more true of very hard high carbon steels than stainless steels, but both can be affected. This is also why using a "steel" on a Japanese knife isn't a good idea -- rather than "wiping up" the bent over edge on a soft steel knife, you will likely cause cracks in the knife edge, it's normally somewhat harder than the steel of the hone, and Japanese knives almost never fold over at the edge, they either wear away or the edge breaks off.

Use diamond plates with great care on hard steel -- you must use VERY light pressure and you will get little or no feedback when you reach the edge. Ditto for the ceramic stones, I suspect they are rather "numb" as well.

Definitely use the 6000 grit stone as a finisher if you want that much polish. Probably not useful with the soft stainless knives as you are more likely to just remove the carbides that make the edge useful, stop before that.

Stropping is a great way to "clean up" the final edge, and what you use isn't critical really, even newspaper will work if it has enough ink on it -- the pigment in black newspaper ink is about one micron in size. You can even use your flattened 6k stone as a finish strop, no need to wet it. Light, quick passes, just three or four each way, should do all you need. It really does help make them super sharp IF you have a good apex first.

I've not watched all the videos, but my personal take on sharpening freehand is that you MUST learn to hold a steady angle all the way through each stroke on the stone. Until you achieve that, nothing else really matters. You can make a quick angle guide by folding paper up -- half of a right angle is 45 degrees, half of that is 22.5 degrees, half of that is 11.25, quite close enough to 40, 20, and 12 degrees which are the "normal" grinding angles.

Use a sharpie to blacken the bevel of the knife at the edge and take a few passes on your medium stone as normal, then use a 20x loupe to see what you are doing, should help you get steady angles where you want them pretty fast. You need a flat bevel from "shoulder" where it merges with the rest of the knife to the edge with as little rounding as you can get, and the edge itself must be "apexed" -- both flat sides meeting at a sharp, clean, straight edge.

A "burr" of metal foil produced by the grit will form, once you have a burr the whole length of the blade, flip it over and grind until the burr is present along the whole length on the other side -- this will ensure that you have 'apexed' the edge, then make a few strokes on each side with lighter and lighter pressure until the burr vanishes. On some steels, you will NOT be able to remove the burr on coarse stones, you will have to work it off on progressively finer ones. VG-10 is bad about this, so are some of the lower grade stainless steels.

Be careful about working it off, if you rip it off with a cork or soft wood, you can make tiny flat spots on the apex and until you grind them out again, the knife will be duller than it should be.

Hope I didn't drown you in info....

You can get decently sharp knives with what you have, certainly - technique is more important than abrasive. Most of the people who post here have very high expectations for the edges on their knives, far beyond what a typical home user would need, or in fact notice most of the time, and sharpening tools, especially waterstones, can be a real rabbit hole if you get into that "ultimate edge" or "ultimate sharpening" thing.

Jon's videos are considered about the best tutorial out there by many people who use their knives all day every day at work, they are definitely worth watching, even if you don't chose to emulate them exactly. What really counts is holding the grinding angle and grinding evenly all along the edge without changing the shape of the knife.

Peter

 

[benichka]

Thank you for your answer.
You mean this chart?
https://www.dmtsharp.com/misc/dmt-chart/?ajax=true

I saw somewhere a "universal" grit chart (on blade forum ?), apparently the grit system is a big mess

I plan to use them for "starter" also...

they'll scratch hell out of your knives and there is little to no tactile feedback

I guess for the scratching one have to be careful not to touch anything else than the edge with it, but it's easier said than done.
For the tactile feedback, that is very true, even for the ceramic plates.

 

[benichka]

Wow, thanks for your detailed answer psfred!
I didn't think of the fact that for the J knives, it could be a problem because of the hardness of the steel... Good to know! I'll keep them away from it
Thanks for all the tips! I knew few of them but it's always nice to have a little "refresh" from time to time

 

[daveb]

I was thinking of one like this, the DMT fine being equivalent to a 600 grit stone.

http://www.imcclains.com/productinfo/documents/Grit Comparison Chart.pdf

 

[benichka]

I was thinking of one like this, the DMT fine being equivalent to a 600 grit stone.

http://www.imcclains.com/productinfo/documents/Grit Comparison Chart.pdf

From what I see it's what DMT wrote on their grit chart (no wonder: they specified their grit also in micron), except for the XXF that's more like a 4000 JIS New that a 8000.

Thanks for the link! The precisions in this document are very interesting.