Inukubi Steel Plane Blade

[Stanley Covington]

Temporary insanity struck me yesterday while at the Kezuroukai, and I bought a 70mm finish plane by Yokoyama made using Inukubi steel.

From what the retailer said, and what I have gleaned from the web, the metal is basically high-speed tool steel developed originally for metal-cutting bits and lathe tools, holds an edge forever, can be easily sharpened with everyday waterstones (really??), is difficult to work (spread) and comes only in rather narrow strips, so the ura on the plane is much narrower (measured from the cutting edge) than what one normally sees. The blade contains a veritable bucket-full of tungsten.

The retailer's wife showed me her own plane with the same blade by Yokoyama which she used to compete in the Kezuroukai (there were two or three ladies there yesterday planing away). Her sharpening technique was notably unimpressive, but she swore it was easy to sharpen.

The subject of this metal has popped up occasionally on this forum, but I have never used it before, and so the adventure begins. What has been your experience?

Stan

http://www.e-kanamonoya.jp/L1080646.jpg
http://www.e-kanamonoya.jp/L1080647.jpg
http://www.e-kanamonoya.jp/L1080648.jpg
http://www.e-kanamonoya.jp/L1080649.jpg

From Tsunesaburo's webpage http://www.tsune36.co.jp/shin_01.html


carbon chrome tungsten moly vanadium


1.15～1.17

1.32～1.35

5.0 ～5.06

0.18～0.21

0.38～0.4

[David Weaver]

I have an inukubi plane made by takeo nakano. It was the first "good" plane that I got and I got it for a song.

On mine, the hagane is stretched more and is very very thin, the iron that backs it is supple, and I think it's a few ticks off of claimed hardness (it's probably low 60s). It's a very easy to sharpen plane, sharpens on all of my natural stones without issue. Some of the ease may have to do with how thin the lamination is, but it is a very pleasant plane to use because of it.

In wear and in sharpening, to me, it is like a good carbon steel plane. If there is a lot of increased wear resistance due to the carbon, I haven't noticed it too much, but at the same time, the iron has held up well in use and wear occurs without chipping and it does so at a comfortable 27 or 28 degree bevel.

I think in the balance of the claims about it, it does sharpen easily. It doesn't hold an edge forever, but it is respectable in how long it does. It's a lot like the old high speed steels, not rubbery like the new ones with moly and chromium in large amounts. If yours turns out to be like mine, I scratch out the kanji and give it to you and tell you it was carbon steel, and you might say that it was a little soft and not much else and be very happy with the way it works.

So loves yokoyama. I'd be curious to hear what you think about his work, even though my buying days are over. Nakano is known as a maker who tries hard to keep his price down, but still do good work. I haven't seen any of the big -time peddlers gushing about his work, but that may be because they can't get the same amount for it as they can for kunio and others. I do like the relatively plain and tasteful iron.

[David Weaver]

Here's the nakano blade. I read that a lot of makers make it in shorter blades because it's hard to stretch, but nakano just stretched it all the way out (though very thin once he did that). Stan, you were the person who helped me in this thread. It does have my three favorite plane irons, they are all three very fine grained. the ogata and the nakano iron are a little softer than the mosaku, and truth be told, the nakano inukubi iron is the most pleasant to use except for the fact that mine came in an unsigned (but ledged) dai that has the cross pin improperly installed so that I can't get the subblade all the way to the edge.

http://www.sawmillcreek.org/showthread.php?161006-Need-an-Assist-on-Japanese

[Stanley Covington]

Thanks for the input.

Yokoyama has an excellent reputation, and his prices are certainly reasonable if his blades perform as represented.

From your comments, it sounds like your blade combines the best of all worlds.

All the tungsten chrome and vanadium would seem to indicate high wear resistance and retention of hardness when exposed to high temperatures on the positive side of the scale, with the likelihood of being very difficult to sharpen and not accepting a very sharp edge on the negative side. I have been working with tropical hardwoods with high silica content a lot the last few years and wanted a blade that could handle the abrasion. It will be interesting to see how it performs. I will post comments in a few weeks after I have sharpened it a few times jammed some wood through its throat.

BTW, the Mosaku is not behaving well even at the high angle.

Also, Ito san said he will heat treat the gagari this month, but won't have the teeth cut and testing done until the end of July due to the need to get a professional sawyer involved in determining the ideal quantity/progression of teeth, and the degree/progression of rake. A difficult equation it would seem.

[David Weaver]

I don't think my inukubi plane would hold up on tropicals the way that togo reigou or super blue would. I don't know, though, I never used mine on anything harder than maple.

It's unfortunate that the mosaku isn't turning out to be good. Is it too hard tempered, or is it not that hard and just defective instead? Will suehiya take care of it if it doesn't resolve?

[Stanley Covington]

I don't think my inukubi plane would hold up on tropicals the way that togo reigou or super blue would. I don't know, though, I never used mine on anything harder than maple.

It's unfortunate that the mosaku isn't turning out to be good. Is it too hard tempered, or is it not that hard and just defective instead? Will suehiya take care of it if it doesn't resolve?

Looking at the ingredients shown in Tsunesaburo's chart (pasted in part below) makes me think that Inukubi (dogneck) is much closer to High Speed Steel than Togo is with lots more chrome, tungsten, moly and vanadium.

I checked with a couple of more well informed sources today and they confirmed that Yokoyama's blades have a very good reputation.

The Mosaku has me a bit concerned after speaking with those same sources today who said that Mosaku has a reputation for making hard, excellent blades, but that every once in a while, a blade will get overheated and become hopelessly brittle and crumbly. But I will continue to have faith, since two sharpenings is not definitive, and endure through 2 or 3mm of wear to see if the blade settles down. If it doesn't, I will take it back to Mr. Suzuki's shop near Ikejiriohashi (near Shibuya) for a refund or an exchange from Mr. Suzuki (not Suiheiya). I believe he will exchange or refund if I explain the situation and show him the failed cutting edge.

Stan

Carbon Chrome Tungsten Moly Vanadium


Super Blue
1.4 ～1.5
0.3 ～0.5
2.0 ～2.5
0.3 ～0.5
0.3 ～0.5






Dogneck 1
1.15～1.17
1.32～1.35
5.0 ～5.06
0.18～0.21
0.38～0.4






Togo 1
1.4 ～1.5
0.5 ～0.6
2.5 ～3.06
0.05～0.08
0.16～0.2






Carbon Chrome Tungsten Moly Vanadium

HSS
ＳＫＨ５１
0.8 ～0.9
3.8 ～4.5
6.0 ～7.0
4.8 ～5.8
1.8 ～2.3






Powder
ＨＡＰ４０
1.27～1.37
3.7 ～4.7
5.6 ～6.4
4.6 ～5.4
2.8 ～3.3

[Stuart Tierney]

Closest steel I have is Swallow steel, which isn't the same but it's not too different either.

It's noticeably more troublesome to sharpen than blue #1, it doesn't seem to take the same edge as blue #1 (although I've not pushed it) and while my blade isn't crumbly, it is hard. Hard as hades. I reserve that one for nasty woods like some old jarrah Derek found for me. Deals with that stuff no problem. I've never used it softwoods.

I've not thought of a genuine personal need for any of the Togo steels for myself.

Stu.

[Stanley Covington]

Closest steel I have is Swallow steel, which isn't the same but it's not too different either.

It's noticeably more troublesome to sharpen than blue #1, it doesn't seem to take the same edge as blue #1 (although I've not pushed it) and while my blade isn't crumbly, it is hard. Hard as hades. I reserve that one for nasty woods like some old jarrah Derek found for me. Deals with that stuff no problem. I've never used it softwoods.

I've not thought of a genuine personal need for any of the Togo steels for myself.

Stu.

Thanks, Stan

[David Weaver]

Keep us posted, Stan. So far, I've had planes in white #1, #2, special blue cutting steel (that yamamoto does in a LOT of planes), inukubi, super blue and some sort of swedish blue-type steel.

The super blue was the gummiest of the bunch, but on synthetic stones it was good tempered. It would've required some friability on natural stones. All in all, for a japanese steel, tough and abrasion resistant. I did not have it long, but I'd bet a few more sharpenings in and it will be much tougher.

Special blue cutting was a notch off of that, very gummy for what it is and yamamoto likes a thick lamination line and maybe the grade of kamaji wasn't up to snuff compared to most of my other planes, because it was intolerant of the natural stones, at least on a practical level if you were chasing the best edge you could get and counting time while doing it. Good steel on synthetic stones, though...really good for general planing.

Both nakano's inukubi and ogata's swedish blue steel are very supple on the natural stones and willing to give up dense streaks of iron. Nakano's lamination is so thin, though, that might be the cause. Ogata's lamination was thick, I think the iron may be on the softer side, and maybe the designation of swedish blue is not correct, maybe it's just assab 120 or something very plain. Both of these planes have very soft backing.

I have heard stories about swallow steel being gummy, and inukubi is definitely not in the same class in terms of that. The tungsten doesn't really impede abrasion as much and doesn't give the steel the clumpy gummy feeling. I guess it probably increases the temper temperature by a fair amount, which should equate to better wear in fast planing. So describes it as feeling like carbon steel, and I'd agree. It is less difficult to sharpen than my mosaku white #1, the latter might be a bit too hard and maybe mosaku's iron isn't as soft as what nakano uses.

I agree with stu on the boutique steels. But it's hard to turn down when someone wants to unload an unused plane for $250 with a presentation box (not that I'd pay extra for the presentation box, but I'll take it when it's free).

Big variable in this might be what kunio did with the iron. If he left the lamination thicker and made it much harder, it could behave entirely different from my experience. If it hones nicely on natural stones, though, I think you'll be in for a treat in terms of how much you like carbon steel planes, though. It won't turn you off by being like rubber on the stones or fanning out a big wire edge.

(I do have a japanese razor that is marked "tungsten steel" also, and probably from between WWI and WWII, but hard to tell. It's a little less forgiving on the dullest of natural hones, but it shaved well and didn't fan out a fat wire edge like high chromium steels do)

[Stanley Covington]

An update on the Inukubi steel plane blade by Yokoyama, Mosaku 60mm plane blade, and Koyamichi chisels.

Compared to White Paper Steel 1 or Blue Paper Steel 1, or any other steel I have experienced other than straight-up HSS, the inukubi blade is a bitch to sharpen, and crumbled badly the first sharpening on diamond plates. Care is required. I will keep you posted on its performance.

The Mosaku 60mm plane: After four sharpenings and perhaps 2mm of steel removal using diamond plates, it appears to have settled down, but it is still at an angle of about 34-35 degrees. I will continue to reduce the angle gradually over the coming months and see if it will retain an edge without crumbling.

I spoke with two craftsmen I have known for many years and who's opinions I trust and asked their thoughts on Mosaku and Koyamaichi. The most interesting comment was that Mosaku can make a fantastic plane blade occasionally hitting the ball out of the park (using a baseball analogy) but that he is a 30% batter. A bit discouraging.

I also asked about Koyamaichi chisels, since the guys on this forum talk about them a lot, but I have never seen, let alone used one. The comments were that Koyamaichi is a Miki smith, of course, and that he is "new school" relying on scientific methods rather than just human senses. They said his products are well made, easy to use, and very reliable. Not a Kiyotada or Ichihiro level product, but still better than most chisels produced nowadays. They said they had never heard of any bad products finding their way out the smithy door. Pretty high praise for a consumer-priced product, IMO.

[David Weaver]

It's strange how the difference in makers makes a big difference in the inukubi. Of course, nakano didn't make my iron as hard as yours and the lamination was stretched a lot thinner, so those two things may create the illusion of easy sharpening.

I must've gotten one of the mosaku irons in the 30 percent. If that's the case, it's caused me to mislead people. If I had your iron, since I don't have a reasonable option of exchanging things over here, I would put it in the oven at 250 degrees for an hour and see if it settled it. And if not, then 275. Above that would make the iron soft, but I would probably do it, anyway, in search of an iron that didn't chip. I can't stand irons that chip.