laminated irons (again)

[nabs]

A while ago I started to investigate the economics of laminating (aka steeling) plane irons in the 19th C - I know, I live on the edge (both literally and figuratively!).

This of course turned out to be something of a fool's errand given all the factors involved, but I am persisting anyhow.


I have managed to track down contemporary material and wage cost estimates for 1850s and the potential material savings from making a relatively large item like a thick laminated plane blade from a cast steel bit and a wrought iron backing - compared to a solid steel item - are surprisingly large. If my sums are right it is certainly enough to fund signifcant extra effort in the lamination process, given the comparitavely low cost of labour.

However, one of the many things I know nothing about is the difference in the actual manufacturing process of a solid steel edge tool vs laminated. I have got a vague understanding of the extra steps from this Peter Ross video:
http://www.pbs.org/video/2365386383

.. but I am left with millions of other questions. Do any of you have any experience/insight/opinions on the below?

how many plane irons could a forger be expected to do in a 10 hour day? What kind of reduction in productivity would happen if they were laminating ?

Are there any compensating savings for lamination? for instance, one thing I read is that the effort of creating the initial basic shape of the tool from a bar of wrought iron might be much less than using solid steel (does the steel require more heats, is it harder to shape?)

what about impact on grinding?

what about rejects - is one approach more error prone than the other?

etc!

 

[Cheshirechappie]

Not sure I can give full, definitive answers - but one or two points, anyway.

Yes, high carbon steel is harder to forge than wrought iron. Indeed, straight high carbon steel is quite difficult to forge, for two reasons. First, because it needs more urge from the hammer, and second because it's quite temperature sensitive. It doesn't like being overheated, and it's liable to crack if worked at too low a temperature ('hot short' in the jargon), so the range of heats between which it can be worked is much tighter than wrought iron (or later on, mild steel). That means more skill on the smith's part.

I don't know for sure, but I suspect that when laminating, the blanks were roughed out, then the forge weld made, then the laminated piece finish forged to shape. I do know that most of the grinding was done BEFORE hardening and tempering - it's much easier to grind unhardened steel! Any grinding after hardening was just to clean off scale, and apply the primary bevel.

Don't really know whether that helps much, but I offer it for what it's worth, anyway!

 

[D_W]

i have no insight, but the following considerations come to mind:

* the steel is water hardening steel (in the old ones - not sure how easy it would be to laminate any modern steels to wrought). It's very difficult to harden without serious warpage by itself. I'm guessing that laminating it to something makes its behavior in the quench a lot better

* the users who were using planes in a shop with no powered grinder would much appreciate the thinness of the lamination vs. the thickness of an all steel iron. Later all-steel irons are thinner, even though it would cost little to make them the same thickness as the 3/16" business-end laminated irons that were relatively common. There is a loss with the loss of thickness, and that is in the amount of taper. The more taper, the better the double iron stays seated on a certain part of the iron (the modern steel irons - not modern now, but like the stamped irons that are all steel from sheffield but with some taper - they have some trouble keeping the cap iron affixed to the same spot when adjusting the iron. On a try plane, this is important. (edit: I think I probably didn't make the point well here. In order to compensate for the lack of lamination, later irons are thinner. Thicker would be really hard to grind, but in losing the thickness, you lose some of the functionality of the iron. Something a professional would've noticed. I'm not even a professional, and between my two planes - one I didn't make as nicely early on had a very nice NOS butcher double iron set. The later one is greaves or something of the sort, but very thin and the taper isn't as good and the hollow isn't there on the back. It's perfectly functional, but not as good to use. The lack of ability of the cap iron to stay set well without fiddling (scuffing the bottom of the screw, waxing the top of the cap iron and the back of the wedge) makes the plane less nice to use when you're dimensioning lumber and just want to keep moving).

* the lack of steel above the cutting bit means that you get to slot wrought iron instead of steel - I think that's probably a tooling gain, especially pre high speed steel.

I haven't looked that closely at all of my irons, but the later cheaper all steel irons have often lost the hollow that is cut into the back of the iron itself. That is a nuance that makes an iron bed well even if the bed of a plane has a little bit of high centering from wear.

Savings-wise, I think there is a modern issue here, and that is that relatively unskilled labor can take bar stock and run a machine to cut it into irons. To make a proper vintage laminated iron and cap iron, unskilled labor wouldn't do. Manufacturing 175 years ago would've been filled with skilled laborers, but pretty much everything done between then and now has been done to lower the skill level of the labor so that the costs can be driven down (furniture, tools, etc).

edit: after comment from above - to keep making laminated irons is probably not a big deal. You have the process, equipment and information (knowledge) in place. Starting it from scratch would be another thing entirely. It would take someone who wanted to do it and then the reality is there's probably no market for laminated irons because ...well, who is going to pay extra?

A functional compromise might be something like getting japanese rikizai (prelaminated material, which is also expensive - but it's used in a lot of japanese irons that are just cut) in white steel #2, and making an iron from that. George Wilson told me that the blacksmiths had a lot of trouble forge welding higher carbon steel to wrought, so they settled on going back to 1070, which makes for an iron that's not durable (this is at williamsburg, and involves Peter who you showed). Maybe some of that has to do with the quality of the wrought - could've been recycled architectural stuff with a lot of silica in it, but I don't know. I pushed George to give me an answer - he has a lot of respect for Peter's skills - one of the few people George refers to as a "master" of his craft, and said "if they can't laminate 1095 there, why can some of the japanese smiths laminate 1.35% carbon steel at low temperature?". He laughed and said "maybe they're not as good as the japanese smiths"

There's no discontinuity in the japanese lineage, though - so they're not left figuring out how to do things like the guys at williamsburg are. Point being, if Peter Ross has trouble forge welding high carbon steel to wrought, you might have trouble, too (or whoever you hire). The quality of the forge weld needs to be pretty much perfect - if there are voids (which are common), then the iron is to be junked or sold as a second.

 

[nabs]

thanks both - I found two more videos that shed a little more light on the difficulties with welding cast steel you outlined.

Almost in passing the blacksmiths mention three different potential problems:
1. the metal can split when worked too cold (mentioned specifically in relation to wrought iron, where the grain like structure creates weak points)
2. where the metal 'burns' (oxidizes) because it is too hot
3. where the metal crumbles because it is too hot (it is 'hot short')

on further digging I found out the 3rd issue is a result of impurities (e.g sulphur) forming compounds that melt at a lower temperature than the rest of the steel and in doing so cause the grain structure to fail.

2 or 3 are apparently challenging when doing the weld as the temperature needed before the two metal will fuse is close to the point where cast steel can overheat.

The video also mentions Cheshire's point that cast steel needs more effort to hammer into shapes than wrought iron, and also that (despite this) it is more work overall to create a laminated tool than a solid steel one .

Peter Ross says in the same video that the cost savings from the reduced need for steel justified the extra work in the 18th century (admittedly he is talking about axes, rather than plane irons), and I am pretty sure this was also true in the 19th (and per DW it is a happy coincidence that this made sharpening easier for the thick irons typically used in wooden bench planes at that time).

I would still love to learn more about the process though!
[youtube]TRnAzsyPZ8s[/youtube]
[youtube]1SLGJT6nE_w[/youtube]

 

[D_W]

#2 in your list is why the japanese old-school blacksmiths who worked at night were so fanatical about temperature control (it's much easier to judge the temperature of the metal at night). They are pushing the limits of trying to laminate something really difficult to laminate, but do it at the lowest possible temperature at the same time to preserve absolute edge taking and holding. And, I'm sure they are doing it with power hammers, which peter probably didn't have the luxury of doing. Certainly the English manufacturers would've used power hammers - even if they were the type with a metal bit strapped to a long beam, and driven by water power.

Anyway, I've used a couple of irons from those traditional japanese smiths, but sold them (mosaku was one that I had two irons from). They are fantastically hard, but I think it's sort of a display of capability that isn't practical to use. The irons are nicer when they're a click or two off of that level in hardness, and old japanese texts talk about putting something in the sun (presumably on a black object) to alleviate some of that. Also, the irons that are actually hardened by judgement by traditional smiths will vary a little bit. Sometimes some of them are almost untempered, and they fracture if sharpened with harsh abrasives, but can't be cut by anything natural that isn't extremely friable - that's slow going, and the balance of sharpening for wear never comes out in favor of that. If you get one that's a bit soft, then you have a hand-done iron that's in the same class as something made cheaply by Iyoroi, so what's the point? Mine have been overhard if anything (including one of my chisels made by an old school maker - it needs to be tempered, but I'm not sure if it's something that should be done because the maker's popularity stems from hardness and the maker is from tokyo and dead 15 years now).

That said, I think the technical difficulty in doing this well is harder than we'd know. If Peter and the smiths at CW struggled to do it, perhaps it can be done with higher heat but at the cost of burning the steel bit and then there's really no advantage - you just end up with a less durable laminated iron. The high quality bitted irons, even from England (talking about the old ones, not the ones made in the last 125 years) can be quite hard. I'm sure that was on purpose - and it takes doing the process right.

One other advantage to bitted irons for the hand sharpener (and it's an artifact now that we have strong cutting synthetic abrasives), the wrought iron in a bitted chisel or plane iron will literally pull particles from most stones - especially slates, but even washitas. I can sharpen a japanese chisel on a washita indefinitely even though the hardened edge would grade the washita and cause it to stop cutting. The wrought keeps it fresh, and will even wake up one that you've intentionally allowed to become dead.

At any rate, to make something that's very good, and not just another record iron (record irons are fine, and it's nice that they're laminated, but they're no better and maybe not quite as good as stanley's non-laminated sweetheart and prior irons - definitely not as good as stanley's old V logo laminated irons)....well, to make something really good, I think that's probably going to be hard.

It also would deserve someone who understands what shape the iron should be, size and proportion, or it will be a piece of art that doesn't function as well as an iron that I can order directly from the UK out of old stock for $35.

What are your thoughts in general - irons for wooden planes, or irons for stanley/record/lie nielsen planes? If it's the latter, tsunesaburo has a decent rikizai product in blue steel that's not too expensive. It's actually much better than decent, I guess - it's blue steel rikizai and it's sort of like a super vintage iron, but you have to have something that can sharpen 65 hardness steel. If you do, it may be the best smoothing iron that you can buy now.

 

[nabs]

given my hamfisted woodworking skills I am more than satisfied with whatever irons came with my planes - I am just curious about the historical side of things. I did not know that wrought iron helps to keep natural stones fresh - another interesting feature!

I am sure you are right about power hammers, particularly by the 1850s (which is the period I am looking at) which would have mitigated any potential delays forging a solid steel tool - this is one of the reasons that I am pretty confident the reason for laminating the tools was just that it was cheaper overall to minimize the use of cast steel, despite any extra work needed (and therefore we can conclude the blacksmiths were skilled enough to minimize the number of rejects for it still to make economic sense).

I also remember reading somewhere that the ability to weld cast-steel to wrought iron was not perfected until the end of the 18th century (can't remember where I saw this though!) - I wonder if it had something to do with new techniques in making cast steel that reduced the number of impurities, thus reducing the #3 issues?

out of interest, why is it important to the Japanese that the bits welded on are very hard (or at least harder than was needed in the West)?

 

[MusicMan]

There is an important advantage to laminated steel that has not yet been mentioned, that is in controlling the overall properties of the blade. You need a hard steel to take and keep a sharp edge. But these are brittle, hard to shape overall and prone to cracking, either from mechanical damage or from quenching stresses. Wrought iron (largely pure iron plus slag inclusions) is ductile but does not take an edge. Many items have been made, by Japanese smiths and others, that are designed to combine these properties, by having a hard edge and a ductile backing.

This has been done in many ways. I had the pleasure as a young metallurgy student of working with Cyril Smith, the Manhattan Project metallurgist and by that time a great guru, on a samurai sword, in which we examined cross sections in a metallurgical microscope. It turned out that for the final heat treatment the bulk of the sword was encased in clay, leaving the edge bare. Heating to red heat and then quenching gave an extremely hard edge but left a strong but ductile backing and interior. Thus the sword would fulfil its function of slicing an enemy or a slave from shoulder to waist without breaking. (I am told, but cannot verify this, that there was a verb in Japanese that meant "to test one's sword out on a passer by"). Case hardening is another example, where carbon is diffused in to the outside of a wrought iron (or low carbon steel) object to provide a pardonable skin after heating and quenching. Induction hardening works in a similar way. In this case the whole steel is hardenable, but only the surface is heated by induction, to be quenched and hardened. And solid-state weld lamination as described above is the obvious method when one only needs on edge of the blade to be hard, as in a plane.

I thus very much doubt that laminated steels were introduced for purely economic reasons; they may have been economical but they were also the best material for the task.

 

[D_W]

We can have the hardness in japanese irons, etc, though, in relatively simple steels. They would be brittle, but it probably wouldn't be a deal stopper in planes with a cap iron (or even without). What would be, though, is that 65 hardness would not work with any natural stones (my japanese chisels claim 64, but they are probably closer to 61), not even japanese natural stones.

This kind of hardness was available 150 years ago, too, with file steel.

I'd guess (I'd love to see someone with a versitron test this theory) that most of the laminated stuff that's on the hard side is probably 60 or a click higher. Anything above that is defective. The first good unused ward iron that I bought was probably 65 hardness. I quickly figured out why it was unused - nobody could flatten it or hone it, and it and the plane it was in got set aside. I've had similar experience with "deluxe" irons offered in american planes in the late 1800s. They weren't common, but once in a while, you'd find a plane with a 1/4" thick iron (at the business end) and they are usually little used - even when laminated, they're a pain.

At any rate, I think there's a lot of documentation about cost being the early driver. There are cases where laminated isn't better (mortise chisels, timberframing chisels, etc) and where differential hardening of solid steel yields a better tool. Delamination of chisels is common right at the line where the bit is welded to the rest of the chisel (unfortunately, I managed to do the same thing to an old framing chisel, and George Wilson, the toolmaker at CW mentioned that it occurred there). Good cast steel in the late 1800s (was it even cast steel at that point? I'm not much of an historian) was expensive enough to make it worth the trouble to laminate all by itself, and not all laminated irons take advantage of the dampening of the cast.

in reality, many of the vintage japanese irons aren't really that hard, and when they are, they often show up (I can get them cheaply on japanese proxy auctions) little used because traditional sharpening would've been entirely by hand. The irons around 61 (japanese) don't last quite as long in use, but they're many times easier to sharpen and preferable for anything aside from the absurd japanese tradition of zero sharpening on the jobsite.

All that said, there's a photographic negative of the opinion on here on some other forums, that modern steel is far superior to vintage steel. I will get some vintage steel under the microscope (I've got stuff back to the early 1800s). It'll be interesting to see if the voids that show up on my AI chisels (made of modern O1) show up on vintage steel. I'm going to guess that they don't, because a tradesman would've snapped steel and examined the structure to grade steel for sale. I'll bet they would've seen the small voids and rejected it - something that's not being done with modern process.

 

[D_W]

out of interest, why is it important to the Japanese that the bits welded on are very hard (or at least harder than was needed in the West)?

Apparently, they have a tradition of not sharpening on the job site. They also have a fascination with planed wood for interior architectural work and want a polish off the plane (the harder a steel is, the finer the edge it will take off of natural stones until it gets to the point that it's so hard that natural stones will only burnish it) because interior work is often left unfinished.

So, it doesn't really translate to usefulness in the context of western woodworking.

They also limit the clearance in their plane to chase a low effective planing angle, and lower clearance means more sensitivity to wear rate. Hardness breeds wear resistance (when the alloy is held constant) as long as there's enough toughness.

 

[nabs]

thanks both - it is interesting to know that one of the properties of the laminated iron is that you can make the steel harder than otherwise. But given DWs point about the difficulties sharpening even thin bits of very hard steel it makes me wonder if that was really a motivation (well at least in edge tools - not sure about swords!).

Also, a metallurgical question for Musicman: is it a general truth about metal that as it gets harder it also gets more brittle and prone to chipping/breaking, or can this be avoided by manufacturing techniques? The reason I ask is that if brittleness was an unavoidable consequence of hardness, then this would be another important factor for the 19th C makers to consider, since chisels/plane blades will get whacked into hard knots etc now and then, and it is a pain having to grind out a chip (much more of a pain than touching up a worn edge!).

 

[custard]

most of the laminated stuff that's on the hard side is probably 60 or a click higher. Anything above that is defective. The first good unused ward iron that I bought was probably 65 hardness. I quickly figured out why it was unused - nobody could flatten it or hone it, and it and the plane it was in got set aside.

About ten or fifteen years ago Karl Holtey offered the option of a super hard steel for his plane irons (I can't recall the steel's name but I think it might have been called S53?). I've got a couple, including one he made for regular 2 3/8" Stanley or Record bodies. They're just too hard to be practical, I can only sharpen them with diamond stones, diamond paste, and far too much hard work. Karl dropped them after a few years so I guess I wasn't the only one that concluded you can have too much of a good thing!

It's similar with other woodworking tools, there are some super hard card scrapers currently on the market. With a carbide burnisher they can be made to work, but it's an impractical amount of work to polish and flatten them off and I can only get them to deliver a very aggressive hook; fine for stripping off varnish, but a non starter for flushing down inlay work.

It's part of a bigger theme I see played out regularly in woodworking and wood finishing. It should be a harmonious system where every tool, ingredient, and technique are mutually compatible; but when one element of that system starts to step outside the boundaries then the whole thing falls over. A traditional apprenticeship and formal training might be too prescriptive for modern tastes, but at least they deliver a complete solution that's proven to work. The internet age seems to promote the kind of cherry picking that results in dysfunctional combinations and a culture of over hyped "ultimate" solutions.

Just my 2p's worth!

 

[MusicMan]

Also, a metallurgical question for Musicman: is it a general truth about metal that as it gets harder it also gets more brittle and prone to chipping/breaking, or can this be avoided by manufacturing techniques? The reason I ask is that if brittleness was an unavoidable consequence of hardness, then this would be another important factor for the 19th C makers to consider, since chisels/plane blades will get whacked into hard knots etc now and then, and it is a pain having to grind out a chip (much more of a pain than touching up a worn edge!).

Yes, in general it is, since brittleness is avoided by allowing some plasticity (ductility), which blunts the cracks and stops them spreading catastrophically in fracture. Alloy development is used to increase the hardness at which this happens, and manufacturing process, mainly heat treatment, is used to elect the blend of hardness and ductility (toughness) for a particular application. And as Custard says, the ability to sharpen is crucial for woodworkers. It isn't crucial for metal processing hence the use of tungsten carbide tools, which can remove massive amounts of metal in one cut. A pure carbide chisel would be essentially unsharpenable in the wood shop; and even when new would not be quite as sharp as steel because of its grain size.

I still think that laminated steel (thin hard on top of thick ductile) is the perfect structure for most wood tools, and I'd be very surprised if the historical makers did not know that. I've studied historical metallurgy a bit, and one thing i learned is never to underestimate the skills of historical craftsmen and the practical knowledge that is built up by tradition.

Keith

 

[nabs]

thanks, that is a good explanation. since the benefits for the manufacturer (costs; more latitude on hardening) coincide with benefits to the end user (good balance of edge retention vs ease of sharpening; price) there probably is no single answer to the question 'why were tools laminated' (or rather the answer is 'all of the above'!)

re the last point, I realized there was a huge amount of practical experience with steel tool making in places like Sheffield by the 1850s, but having looked at some of the contemporary literature I was surprised to find out how much discussion there was on chemistry and metallurgy too - will post some links later!

 

[D_W]

I still think that laminated steel (thin hard on top of thick ductile) is the perfect structure for most wood tools, and I'd be very surprised if the historical makers did not know that. I've studied historical metallurgy a bit, and one thing i learned is never to underestimate the skills of historical craftsmen and the practical knowledge that is built up by tradition.

Keith

A specialist made the steel, a specialist examined it and the customers were professionals who couldn't afford to waste money. That adds up to the product being excellent in general, despite some modern notions that 100% uniformity is better than how absolutely good something is.

The spec sheet notion that higher hardness means better steel is another modern thing. I don't like dead soft irons, but I've got two that you could almost file, and as long as you don't use them in a smoother (I've got plenty of use for non-smoothers), they are really wonderful. If you used them in commodity work, they could do smoothing fine, too, they just can't hold the tissue paper shaving type edge that everyone wants to use now between their 9 minute sharpening sessions.

The only thing I can really think of that came very late in terms of the improvement cycle was perfecting straight razors. that didn't occur until about 1900, but that had more to do with hardening and tempering and developing cutler's tools to work with something so thin and hard.

 

[nabs]

so....it seems likely that until the middle of the 19th century (at least) laminated irons were the preferred option, being both cost effective for the manufacturers and being easier to sharpen for the tradesmen who used them.

We also know they eventually fell out of fashion in the 20th century, at least in the UK and the US (perhaps because of the popularity of thin stanley irons, where the sharpening time-savings are minimized, and perhaps because the cost equation changed so that laminating became more costly than creating solid cast steel irons).

What happened in between I hear you cry?! Well taking a look at Howarths 1884 catalogue we see that they offer both Cast Steel chisels and Common chisels.

Helpfully the catalogue explicitly says that the former are solid cast steel and the latter are steel lined. The section on plane irons does not explicitly say solid vs lined, but does keep the terminology of Cast Steel and Common so I think it is safe to assume it is the same distinction.

Perhaps unsurprisingly the Cast Steel versions are the more expensive (by about 15-20%), but my question is why are they there at all? If laminated blades were superior from an end-user perspective, why offer a more expensive/worse option alongside it?

answers on a postcard please!

Also, I notice on the catalogue pictures that the abbreviations C S (cast steel) and G S are used. Presumably GS relates to the 'common' variety, but what does it stand for?

More thrills await us when we peer into the Mathieson catalogue from about the same time. Stay tuned, and please answer my questions above!

 

[custard]

so....it seems likely that until the middle of the 19th century (at least) laminated irons were the preferred option.

We also know they eventually fell out of fashion in the 20th century...perhaps because of the popularity of thin stanley irons

Record and Stanley used to have thin laminated plane irons, jolly nice they are too. I'm no tool historian so I don't know when they began or when they ended, I guess it was pre war. There's also some suggestion that they were subbed out and possibly all plane manufacturers got their laminated irons from the same source?

record-stanley-laminated-plane-irons-t106851.html

 

[nabs]

yes that is another intriguing bit of info + the fact that Stanley did produce adverts justifying their decision. I wonder if they were actually a re-introduction after solid cast steel became dominant? Although then you have to ask why Record would have done the same without any fanfare (no mention of them in planecraft!) - unless of course they were simply copying Stanley (as they did with every other aspect of the bench planes ). Most mysterious!

 

[custard]

yes that is another intriguing bit of info + the fact that Stanley did produce adverts justifying their decision. I wonder if they were actually a re-introduction after solid cast steel became dominant? Although then you have to ask why Record would have done the same without any fanfare (no mention of them in planecraft!) - unless of course they were simply copying Stanley (as they did with every other aspect of the bench planes ). Most mysterious!

Planecraft was first published in 1934. It's possible laminated irons were out by then. I pretty sure they were gone by 1939. If you look at the designs of the tops of the irons it's a bit suspicious they all move in lockstep across all the plane manufacturers, my guess was they were made by a third party. I'm speculating here, not only am I not a tool historian I'm also neither an engineer nor a metallurgist! But surely plane makers are primarily foundry operations, so wouldn't it just be common sense for them to buy in irons from one or more specialist makers?

 

[AndyT]

Also, I notice on the catalogue pictures that the abbreviations C S (cast steel) and G S are used. Presumably GS relates to the 'common' variety, but what does it stand for?

Only an unconfirmed guess, but do you think it could have been "German Steel"?

 

[nabs]

in my reading I have been looking at some of the contemporary explanations of steel manufacture and based on this account ( from the 1850s) I do not think German Steel would be chosen for edge tools, particularly when you keep encountering the continued insistence in these accounts (mainly from the sheffield makers) that cast steel is the best for tools (and the apparent acceptance of this view by all the other countries they exported to).

https://books.google.co.uk/books?id=bOJ ... 22&f=false