Thread: Bevel up Japanese plane blade

No. They're always made with some deference to a shape in the back of the blade to bed bevel down. That is, everyone is aware of the hollow on the side facing up, but the back of the irons generally aren't flat, either.

I'm not sure where the idea started that more and more highly alloyed blades are for harder woods. I asked stu about it at one point because they do have greater abrasion resistance, but most of them have edge stability problems and nicking. both blue and super blue have some edge nicking issues because tungsten carbides don't really cool back in a forged steel matrix evenly. At least not reliably.

White 2 and white 1 both handle hardwoods very well, and I'd bet that the pros used those when they planed a lot of steel - more than steels with carbides that don't hone quickly.

I just looked up the swallow steel alloy - it's a very large amount of chromium. Here's where the idea of using tungsten came from - apologies if you know this already - tungsten carbides dissolve and reduce at regular forging temperatures. at least in some compositions (especially compared to a very plain steel like 1095), they can add notch toughness, which is a measurement of how much it takes to break a steel sample cleanly. It can be hard to get that to translate to a fine edge.

Tungsten is probably expensive, and steel is generally forged to shape now if it is forged to shape and normalized with temperature control set to dissolve carbides, so chromium and vanadium generally take over - they disperse more evenly.

there is a forgeable margin temperature wise for steel - given the difficulty that I've seen in getting a really fine blue steel blade without stray carbides, tripling the carbides for swallow steel is probably more likely to make an abrasion resistant but dissatisfying edge. here's he problem - you can add a little bit of tungsten and the temperature that all of it goes into solution isn't that high. As you add more tungsten, it the dissolution temperature gets higher and I'm guessing that the the average forging won't get the steel hot enough to dissolve the carbides.

Steel used in Tsunesaburo planes. : Tools from Japan, Japanese woodworking tools direct from Japan.

Anything gained in edge life will spring back and be punishing when honing, and especially if grinding out a nick that necessitates taking several thousandths off of an iron. That's hard with plain steel, but punishing to do with a coarse stone with more wear resistant steel.

I asked stu at one point when using japanese planes why there is a notion that the white steel isn't suitable for hardwood and he suggested I wasn't off base with the idea that white steel works just fine.

If we're talking about notch toughness instead of just fine edge holding, when you get to things like knives, double the toughness means generally that an uneducated consumer who buys a commodity knife has to work twice as hard to break the knife. and maybe little nicks in the edge don't matter as much.

Any issue of white steel being chippy in hardwood is generally just a sign that an iron is too hard and should be tempered back a little bit. Many are, but as you get into older planes, there are definitely irons hardened more like low 60s hardness - everyone wants super hard now. Super hard works OK in really gentle wood. In my opinion, you'll spend less overall time sharpening if you find a white steel iron that likes hard woods, though.


High tungsten steels made a brief appearance in razors, too - but they didn't last long there. Razors are probably the easiest to notice when fine edge holding isn't good and the geometric demands/constraints are narrower. carbon steels with only a little bit of additive dominates for a razor that will hold a low angle without chipping. In disposable razors, these are defunct - the blades are designed to dent and fail.

After all of that, I just realized that stu also has a comment on his page about the swallow steel needing a larger included angle than a typical iron so that it can hold up.

That's a red flat that carbides are not evenly distributed or that if they are evenly distributed, they are big with large areas of "other" between them. Lattice or whatever you call the matrix between the carbides.

I'm a bit bonkers about this topic because I've learned over time that things like swallow steel are kind of a novelty - and the rarity of tools made with them and other andrews products (if I'm wrong that it's not andrews, my apologies, but thinking of the togo steels and others) is owed to the fact that there wasn't economic interest to continue to make them the standard tool.

In the world of hobbyists, we mistake this as their being too expensive and better and that the plebes used the plain stuff.

I'm happy to see that Stu's guidelines agree with what I know about blade steels.

I'm sure togo reigo and swallow steel can be set up to take many feet of shavings without achieving the same edge uniformity - I'm going to show you two pictures as I'm telling you something you didn't ask - the steel itself.

This is tsunesaburo blue 1 under high magnification. I did a test a few years ago and his iron is 65 hardness or so and blue 1, and one of the other irons was an O1 steel iron at lower hardness. the tsunesaburo iron should have outlasted the O1 iron, but that's not what happened. They both lasted a nearly identical footage, but the surface was clearer off of the O1 iron. What I didn't compare was end grain - if you planed end grain with both, blue steel may have held up a little bit better just because it's harder (hardness = edge strength - more force before an edge deflects)

https://i.imgur.com/dhmKa79.jpg


Here's the O1 iron from the same test.

https://i.imgur.com/J2OMH4M.jpg

the big line in the middle for O1 is likely a shop contaminant or mineral in the wood - just after these two irons pooped out or as they were pooping out, I ran into a mineral inclusion in the maple test board that destroyed the edge of every iron in the test. Blue steel and a chinese HSS iron were both super high hardness and the dents in them were the smallest, but all needed to be resharpened.

Point in this case, stick to the plain stuff on a smoothing plane. The high carbide steels tend to do better if you're doing something like cutting brass or some manmade materials - no clue why - it may be that the carbides shoulder the load when cutting metals and the matrix just sort of holds them in place until they break. In plain steels, there are no really hard carbides.

Originally Posted by D.W.

After all of that, I just realized that stu also has a comment on his page about the swallow steel needing a larger included angle than a typical iron so that it can hold up.

David, Stu has a current page? I was under the impression he had no online presence these days.

Originally Posted by Chris Parks

David, Stu has a current page? I was under the impression he had no online presence these days.

No page -to my knowledge, he left some parts of his original blog up and I'm not sure how he managed to do that. As in, if he leaves it up and pays for bandwidth or if it just stays up.

I haven't talked to Stu in a while - he bailed me out on something just before he left japan (shipped me a guitar that buyee refused to finish the job on - they offered to throw it away (!!!) because they didn't have a good grasp on how the US follows CITES in musical instruments).

At any rate, I did find his page today just searching for swallow steel composition, and not from my bookmarks....upon a quick re-look, that link above is text from his store page, the footer says copyright 2022. The rest of the comments were just sparked by me remembering the discussion when looking at that chart.

Thanks for the valuable information David. I personally don't have too much experience in using planes with different types of steels. The link you shared is very similar to the one I've read https://www-tsune36-co-jp.translate...._x_tr_pto=wapp

From the chart there, you can see only Swallow Steel is rated as Ideal for hardwoods, this is where I've got the notion. I'm not exactly sure if the rating is based on tests, personal experience or purely theoretical.

Originally Posted by youngjacky

Thanks for the valuable information David. I personally don't have too much experience in using planes with different types of steels. The link you shared is very similar to the one I've read 鋼（はがね） | かんな解体新書 | 常三郎 =播州三木打ち刃物 鉋職人=

From the chart there, you can see only Swallow Steel is rated as Ideal for hardwoods, this is where I've got the notion. I'm not exactly sure if the rating is based on tests, personal experience or purely theoretical.

This is just my opinion, but I think the recommendation is probably a combination:
1) the steel doesn't work that well with an acute edge, which is ideal for softwoods
2) with a little more edge bluntness, it'll work OK with hardwoods and wear a long time and maybe if it leaves little lines on work, something else can do the last several passes.
3) I don't know if the steel was developed as a blade steel, but maybe it was developed for something other than plane irons where the seller was pushing the limit on tungsten and carbon. It's probably the case that the dissolution temperature of carbides (important for forging or normalizing a steel to reset everything before heat treatment) in steel with so much tungsten may be higher than forging allows, so coarse structure is completely unavoidable.

Couple that with the chance that makers want to offer an array of options, even if it's hard to figure out what some are good for, just like knife makers do now. there have definitely been cases of makers following theoretical potential - especially for higher end goods - and coming up with something less practical than the mundane.

It could also be that somewhere in japan, 0.5% of users were processing hardwoods on a regular basis and found a way to use swallow steel that they preferred - what was it (middle planing instead of finish?) and how were they sharpening, etc, would be needed to explain why there was some economic value or perceived economic advantage in doing that.

just as a side comment, I think most super steels give users something to look at after they get bored with the plain stuff. they're brain ticklers, but most probably don't get much actual use after dealing with nicking and hard sharpening and just giving up.

Out of curiosity, I tried reversing the blade on a couple of (single blade) planes- it didn't work at all.

Perhaps it is a matter of full-on ignorance on the part of the seller?