Yikes! Unsharpenable Steel? / Beware of cheap Kanna

[Luke Dupont]

Hi guys.

So, I've had fairly good experiences with cheap Japanese tools in the past. As such, I picked up a 2000yen ($20) kanna at Tokyu Hands the other day. And, all seemed well until I decided to flatten the back and sharpen it...

The blade is apparently of laminated construction, but the steel on the back is insanely hard -- so much so that I suspect it wasn't meant to be sharpened(!).

There was a bit of a buffed bevel on the back which was almost impossible to get out, despite being very shallow. I ground and ground and ground, and wound up wearing out my new 150 grit diamond plate on the sides. I finally got it more or less flat, but it left the blade all chipped.

So, I decided to try to remove the chips by grinding down the bevel side. I was at it for hours on my coarsest synthetic stones. My coarse diamond stone was the only one that seemed to really cut the hard steel, but seemed to just further the chipping, and even it was pretty slow. My India stone and all of my other synthetic stones didn't seem to cut anything other than the soft iron lamination effectively. No matter how long I went, no apparent progress was made in removing the chips.

I've never seen steel anywhere near this hard. I know that some Japanese steels can be extremely hard, but surely not as hard as Al. Oxide or Si. Ox? Is this some cheap throw away tool not made to be sharpened, or are some Japanese steels simply so hard as to make repair work when you chip them extremely difficult? My other cheap Japanese tools are extremely easy to sharpen whilst still being on the hard side.

I guess I should stick to better quality Kanna in the future. There might be some good cheap ones out there, but it seems to be hit or miss.

Lesson learned? Whatever money I thought I saved by buying a cheap tool, was not well spent. I ended up with a worn out diamond plate, 4 hours of frustration, and a dull, unsharpenable tool. Either that, or there's a whole other world of sharpening crazy hard steels that I don't know about and probably don't care to be a part of...

[glenn bradley]

Lesson learned? Whatever money I thought I saved by buying a cheap tool, was not well spent.

So true, so often, eh?

[Derek Cohen]

Luke, are you sure the steel wasn't HSS?

Regards from Perth

Derek

[Jim Koepke]

Is it possible an hour in the oven at 400º might help?

jtk

[Robert Hazelwood]

I really prefer fresh PSA sandpaper for jobs like that, saves wear and tear on your stones and goes faster if you keep the paper fresh. But yeah it sounds like that was some badly tempered steel- too hard and too brittle to even sharpen. Even if it were HSS the diamond stones should have made some progress.

You may know this but one thing to keep in mind with Japanese laminated blades is that it's very easy to keep lowering the angle as you work the bevel, especially when you are trying to remove a lot of material. You can easily remove more material from the jigane and lower the cutting angle from 28 to 23 degrees in a few minutes if you are not careful- that can make it hard to actually reach the cutting edge with the stone and will cause more and more chipping. You have to always bias the pressure on the hagane.

For inexpensive Kanna I like the 65mm "Economy" plane by Koyama that Stu at Tools From Japan sells. Don't know what steel it is, probably white #2, but it sharpens nicely and holds a good edge. The dai is also pretty well made, though the mouth aperture is wider than you'd like for the finest smoothing work.

[Rhys Hurcombe]

Could i please trouble you for some photos of the back(ura) and the bevel of the blade? Maybe just one of how you had the blade on your diamond plate while flattening the back, too. Thankyou.

[george wilson]

You need to get a black and a white ceramic stone. They will sharpen steels that nothing else will sharpen. I made a knife rom D2 tool steel that I couldn't quite get razor sharp until I got my Spyderco stones.

I will repeat that the plane irons I found that held their edges the longest could BARELY be cut with a NEW,FINE Nicholson file. Hardness is not everything. Indeed ,too hard steel will micro chip on the cutting edge,making the planeviron seem dull. It IS dull,but not from wear. It is from being so hard and therefore brittle that it has very little MECHANICAL strength.

HSS is not as hard as many think it is. My expensive hardness tester with a new diamond penetrator checked it out at 63 RC. 1095 is 67 when fully hardened,and must be tempered down to about 55 for a good plane iron,and not above 52 for a fine quality saw blade. The saws we made caused great excitement inm the cabinet maker's shop. Just about every small maker of fine saws,like Bontz,uses 1095 blue carbon shim stock. Trouble is,it is getting impossible to fin it made in USA. I ave a few pieces in assorted thicknesses I'll sell for $1,000,000 000. :)

[David Myers]

You need to get a black and a white ceramic stone. They will sharpen steels that nothing else will sharpen. I made a knife rom D2 tool steel that I couldn't quite get razor sharp until I got my Spyderco stones.

I will repeat that the plane irons I found that held their edges the longest could BARELY be cut with a NEW,FINE Nicholson file. Hardness is not everything. Indeed ,too hard steel will micro chip on the cutting edge,making the planeviron seem dull. It IS dull,but not from wear. It is from being so hard and therefore brittle that it has very little MECHANICAL strength.

HSS is not as hard as many think it is. My expensive hardness tester with a new diamond penetrator checked it out at 63 RC. 1095 is 67 when fully hardened,and must be tempered down to about 55 for a good plane iron,and not above 52 for a fine quality saw blade. The saws we made caused great excitement inm the cabinet maker's shop. Just about every small maker of fine saws,like Bontz,uses 1095 blue carbon shim stock. Trouble is,it is getting impossible to fin it made in USA. I ave a few pieces in assorted thicknesses I'll sell for $1,000,000 000. :)

Welcome back, George. Great to hear from you again.

[Stew Denton]

George,

Likewise, good to see you back.

The rest of you, do we hear a second bid for George's shim stock....$1,000,00,000 going once,......going twice......

Stew

[Derek Cohen]

You need to get a black and a white ceramic stone. They will sharpen steels that nothing else will sharpen. I made a knife rom D2 tool steel that I couldn't quite get razor sharp until I got my Spyderco stones.

I will repeat that the plane irons I found that held their edges the longest could BARELY be cut with a NEW,FINE Nicholson file. Hardness is not everything. Indeed ,too hard steel will micro chip on the cutting edge,making the planeviron seem dull. It IS dull,but not from wear. It is from being so hard and therefore brittle that it has very little MECHANICAL strength.

HSS is not as hard as many think it is. My expensive hardness tester with a new diamond penetrator checked it out at 63 RC. 1095 is 67 when fully hardened,and must be tempered down to about 55 for a good plane iron,and not above 52 for a fine quality saw blade. The saws we made caused great excitement inm the cabinet maker's shop. Just about every small maker of fine saws,like Bontz,uses 1095 blue carbon shim stock. Trouble is,it is getting impossible to fin it made in USA. I ave a few pieces in assorted thicknesses I'll sell for $1,000,000 000. :)

I will echo what George writes. I have a Japanese chisel that is PM HSS (from Stu), and it is extremely difficult to sharpen compared to other chisels. This is due to the abrasion-resistance of the steel, and not simply its hardness (it is hard as well). Use a method (e.g. hollow grind or a secondary micro bevel) that makes honing easier, and use a medium that deals well with this type of steel. Diamond cuts all at the primary bevel stage, and Spyderco or diamond pastes will hone it to a fine edge. Sigma II are good as well.

Regards from Perth

Derek

[Larry Frank]

Derek....can you explain more about abrasion resistance versus hardness with regard to sharpening. I have some difficulty understanding how these are different. To me it seems that sharpening is a process of abrading the edge with finer and finer abrasive media. If we are talking about a tool steel where you have very hard carbide particles in a slightly softer matrix of tempered attenuated the I understand. With steels without hard carbide in the matrix it is difficult to understand.



Thanks

[Derek Cohen]

Larry

There is an excellent essay on this by Crucible Industries here: http://www.crucible.com/eselector/general/generalpart1.html

Much better than I can explain.

Regards from Perth

Derek

[george wilson]

In regard to abrasion resistance: some alloys like chrome are added to certain tool steels to increase resistance to wear. D2 is such a steel. It has about 14% chrome and is also a very hard metal. It was developed to use blades in metal shears,which certainly face a hard life. I have used it for quite a few punches and dies of different shapes. These were mostly for my wife,who makes jewelry. Theses punch and die sets have done 10,000 cycles cutting materials and are still serviceable without re sharpening.

Some materials other than steel are hard on cutting edges. Papers can be abrasive,and when I was young and poor I used to strop my tools on paper after first using a cheap,gray,coarse hardware grade stone. I could get a razor sharp edge if I kept at it long enough. Certainly not an efficient process!!

[Luke Dupont]

Is it possible an hour in the oven at 400º might help?

jtk

Depending on the steel composition, that might not be a bad idea if all else fails.



I really prefer fresh PSA sandpaper for jobs like that, saves wear and tear on your stones and goes faster if you keep the paper fresh. But yeah it sounds like that was some badly tempered steel- too hard and too brittle to even sharpen. Even if it were HSS the diamond stones should have made some progress.

You may know this but one thing to keep in mind with Japanese laminated blades is that it's very easy to keep lowering the angle as you work the bevel, especially when you are trying to remove a lot of material. You can easily remove more material from the jigane and lower the cutting angle from 28 to 23 degrees in a few minutes if you are not careful- that can make it hard to actually reach the cutting edge with the stone and will cause more and more chipping. You have to always bias the pressure on the hagane.

For inexpensive Kanna I like the 65mm "Economy" plane by Koyama that Stu at Tools From Japan sells. Don't know what steel it is, probably white #2, but it sharpens nicely and holds a good edge. The dai is also pretty well made, though the mouth aperture is wider than you'd like for the finest smoothing work.

Hey! All great points!

In particular, I'm interested by your recommendation of Koyama planes. I'm in kind of a funny situation: as I'm in Japan, I theoretically have better access to good Japanese tools. But my google-fu is very poor in Japanese, so I don't usually have luck finding "X" brand planes / tools, and English sites generally import from Japan to overseas. Couldn't find anything relevant to Koyama planes, unfortunately.

Ultimately, I'd like to find something along the lines of white steel #2 planes in 36mm and 50mm sizes. Right now this is more of a "want" than "need", though.



You need to get a black and a white ceramic stone. They will sharpen steels that nothing else will sharpen. I made a knife rom D2 tool steel that I couldn't quite get razor sharp until I got my Spyderco stones.

I will repeat that the plane irons I found that held their edges the longest could BARELY be cut with a NEW,FINE Nicholson file. Hardness is not everything. Indeed ,too hard steel will micro chip on the cutting edge,making the planeviron seem dull. It IS dull,but not from wear. It is from being so hard and therefore brittle that it has very little MECHANICAL strength.

HSS is not as hard as many think it is. My expensive hardness tester with a new diamond penetrator checked it out at 63 RC. 1095 is 67 when fully hardened,and must be tempered down to about 55 for a good plane iron,and not above 52 for a fine quality saw blade. The saws we made caused great excitement inm the cabinet maker's shop. Just about every small maker of fine saws,like Bontz,uses 1095 blue carbon shim stock. Trouble is,it is getting impossible to fin it made in USA. I ave a few pieces in assorted thicknesses I'll sell for $1,000,000 000. :)

Hey george! It's been a while. I always appreciate your expertise in metals.

I've been meaning to check out those ceramic stones you always mention, but forgot what brand they are. So, they're Spyderco? The corresponding grits aren't listed on their website (just labeled as "Medium" and such) so I'm not sure which ones to look at. But, they do interest me. You mentioned in the past that they're somewhat similar to Arkansas stones, just harder and faster cutting. As I quite like Arks, I think I might check them out for those times when I need to cut harder steels. Somehow I keep managing to wear out my diamond plates prematurely with such steels -- I imagine solid ceramic stones should last longer and be more pleasant to use.

The iron does seem to be very chippy. Maybe it just wasn't tempered correctly. If all else fails maybe I can try Jim's suggestion of tempering it myself?

Honestly though, I think I'll just count my losses and buy a better tool.

[Jim Koepke]

The iron does seem to be very chippy.

Some irons settle down after a few sharpening sessions. You may want to give this one a few chances before rejecting it.

jtk