Full Chisel Blog

March 17, 2008

Laid Steel Blades: Plane Irons, Chisels Gouges &c.

Filed under: Laid Steel Tools,Uncategorized — Stephen Shepherd @ 5:42 pm

Laid Steel Plane Iron 

A recent discussion on the WoodCentral Hand Tool Message Board got me to thinking about laid or laminated plane blades and chisels, as well as other woodworking tools.  The discussion was which steel makes the best cutting edge, I asked a question about cast or crucible steel, a common nineteenth century process of making steel.

Now I had heard, and believed for quite a while that the reason for the thin veneer of steel is forge welded to wrought iron was for economic purposes, steel being more expensive than wrought iron, so they used it sparingly.  I now think otherwise.  While steel was more expensive than wrought iron in the nineteenth century, it would have been possible for not that much more money to make the entire tool from steel, but they didn’t do that.

And the reason that they did make irons of mostly wrought iron (the percentage is well over 90% iron to steel), was so that they could harden the steel much harder than if it were solid steel.  Solid steel quenched in brine is very brittle and very hard and subject to breaking.  A thin veneer of steel laid on the back of the wrought iron can be quenched in brine and you are finished no need to temper the steel as the wrought iron remains soft.

I had just thought cast or crucible steel was superior because it was always so hard.  What is superior is the fact that together the wrought iron / steel produce a blade that can be hardened to a state harder than you can solid steel tools.  There are some reproduction laminated steel blades, better steel forge welded to mild steel.  While this is better than solid steel, it is still steel and requires different hardening and tempering as the both steels will harden.

Because wrought iron can’t be hardened like steel it is the perfect material to make the main body of the tool with the layer of steel on the edge.  It is also easy to sharpen as the steel is very thin compared to the soft wrought iron.  You can see in the above photograph of the Cooper’s Joiner’s Plane Iron, the laminated steel ends at the hole for the chip iron and is less than a 32nd inch thick and the blade is 2 11/16″ wide.

It is interesting to note on rusted plane irons the steel is far less pitted than the iron, however the wrought iron because of its nature does not rust away but just down to a slag layer within the structure of the iron.

I explained my theory to a blacksmith and he said that other blacksmiths have wondered why they have oil, water and brine for quenching.  Why quench in brine when it makes the metal so brittle and hard?  He said if my theory is correct that would explain the brine quench.

Our ancestors didn’t make laminated blades because it was cheaper, they made laminated blades because they were better.  When does a theory become a dictum?

Stephen

11 Comments »

  1. Just a comment about iron and steel. Mild steel is actually iron with a very low carbon content, too low to allow heat treating. So if you laminated steel to what’s called mild steel and heat treated the laminate, only the steel would be hardened. Japanese chisels are a modern example of this. While some traditional Japanese makers have access to old wrought iron, most modern Japanese chisels are made with mild steel as the backing.

    While everyone has an opinion, I believe that steel was laid on to wrought iron primarily because of the cost of good steel (crucible steel). Laminated items were always large, such as mortise chisels and plane blades (wooden plane blades were thick). Additionally, the laminated blades were tempered as part of the heat treatment. Steel directly from the quench would have been too hard and would fracture (like Japanese chisels) if mistreated (as simple as prying as part of a chisel cut).
    Additionally, many of the steel cutting items made by our ancestors were bad. The process of forge welding and heat treating was dependent upon the skill of the smith and not all were skilled. We see good blades and chisels today because of “survival of the fittest”. Our ancestors scrapped the worst of the cutting implements and only the good survived to today.
    We have MUCH better steel and heat treating today than was available in the 19th century, at a much lower price. Modern tool makers don’t do laminated tools because they don’t provide any real advantage, not because the tools are more expensive, or the makers don’t know about laminated tools, or…

    Comment by Mike — March 24, 2008 @ 10:53 pm

  2. mike,

    Thanks for both your comments on the iron/steel issue. I am sure I will get a lot of grief for my stance but I do believe I can defend my position.

    Apparently mild steel is not what it use to be as more tool steel and other higher grade steels are being recycled into mild steel. And this change has been noticed over the past few decades according to a blacksmith friend. Without using something called ‘superquench’ can make mild steel hard enough to cut mild steel.

    As for junk being made back then, just like today. And imagine how many wooden hand planes were burned during the depression and how much iron and steel was melted down for the war effort. We are lucky to have some examples to discuss.

    Laminated plane irons are being made today, they are expensive but there is a market. And while we may have ‘better’ steel today, I do believe that it is in combination with a non harden substrate that makes the tool what it is which is a superior tool. The combination reduces chatter and sharpening is easier and the edge is harder than any modern tool I have come across.

    Why would the blacksmith need to brine quench? If you are going to draw the temper then oil or water would work just fine. But a brine quench makes the steel very hard. Why would they make it that hard? And as it is generally protected by the wrought iron, but it does chip and crack, but the end never breaks off. And because the steel is a thin veneer the chip can’t be that big, so they are easy to grind out.

    Stephen

    Comment by Stephen Shepherd — March 25, 2008 @ 5:58 pm

  3. Stephen – there are specifications for steel (of all types) and the modern steel meets those specifications very closely. In making mild steel (and any other kind of steel) the manufacturer does not just throw all sorts of things into the pot and hope for the best. The melt is tested for the component elements and material is added to react with, and remove into the slag, the unwanted components until the steel meets the specifications. The major difference between mild steel and ancient wrought iron is the lack of slag in modern mild steel. While the slag reduces corrosion in weathering conditions, it does little to improve the backing function on a laminated tool. The fact that western laminated tools are not prone to edge chipping is primarily due to the fact that the edge steel is not hardened as much as a modern Japanese chisel (and a modern Japanese chisel is only a few Rockwell points harder than a modern western chisel). Get a modern Japanese chisel, which is carbon steel laid on to low carbon mild steel, and pry when cutting a mortise. You’ll be surprised at how quickly the edge chips. Modern western woodworkers are aware of laminated Japanese tools but the tools haven’t gained much traction. I maintain it’s because they don’t work well for western woodworking, which is in hardwoods rather than in softwoods as in Japan. Everything I see indicates to me that western laminated tools were made for economic reasons rather than for performance reasons. If they were made for performance reasons, we’d see small tools made as laminated tools. But what we see is only large tools laminated, where there was a significant saving in using lower cost metal as the backing. Making a laminated tool added labor cost which was only worth while if there was a savings in material. Once the material got cheap enough, western manufacturers quit making laminated tools.

    Comment by Mike — March 28, 2008 @ 9:29 am

  4. Mike,

    Both you and Larry over on http://www.traditionaltools.us/cms/index.php?name=Forums (scroll down to Woodworking, then Alburnum’s Almanac), make a good argument for your cases. And while there isn’t much I can disagree with, I do own a very small pair of embroidery scissors with little tiny laid steel blades, the rest wrought iron. A couple pair of wick trimmers with laid steel blades. A pen knife with a 7/8″ laid steel blade. Now these are not woodworking tools but they are the tools made during the early nineteenth century.

    I also have some massive tin snips, one straight and one curved, both nineteenth century and both with laid blades. The wrought iron handles are soft and the blades need stones to hone as none of my files would touch them. I did own a pair of very early nineteenth century scissors that had a bent blade when I bought it. The laid steel was cracked but the scissors were in tact. I carefully straightened them out, honed the edges and they worked almost flawlessly. I sold them and the buyer knew they were broken but was happy to add it to their collection. I can sharpen new steel snips, shears and scissors with files but not the old ones.

    Do you think that the grain direction from the manufacturing of wrought iron contribute anything to laid steel blades? Dampening vibrations? It does look like wood, the grain of wrought iron and it is always oriented in the direction of the tool.

    It’s a Grind.

    Stephen

    Comment by Stephen Shepherd — March 28, 2008 @ 7:50 pm

  5. Mike,
    With respect, you’re not quite right. Yes, there are specs for various types of steel. The thing is, that those specs are often the source of the inconsistencies in certain types of steels. For instance, most types of mild steels have had their industrial composition specs widened over the past, say 40 years. Steel plants actually DO chuck all sorts of scrap and junk into the pot; that’s the main reason why scrapyards exist. Rebar for instance (certainly your everyday garden-variety rebar) are made of all sorts of junk; this is because it’s made to a performance spec rather than a meterials spec; rather than having x% by weight of C, y%w of Cr etc.; it has to have at least qKPa tensile strength etc. I once heard a story from a reputable source of a guy finding an intact ball-bearing inside a piece. Obviously this is rebar not A2, H13 or similar high-spec tool-steel, and I suppose it’s not really related to the argument at hand.

    Perhaps I might bring something useful to the table: firewelding/forgewelding is a difficult, fuel-hungry technique. The welding temperatures of high-carbon steel and wrought iron only overlap by a narrow window of a few hundred degrees and it can be difficult to balance all of the required variables. This is especially a problem in laying-on such a thin piece of steel; it will heat faster than the iron body. I have heard that at the American Civil War (mid C19th) good steel cost c.5x the price of iron, obviously varying depending on quality. However I’m not convinced that laying-on steel would have been all that economical overall; once you factor in the increased amount of fuel burned (a good forgeweld typically needs 3 heats to high welding heat), the time taken and the number of losses that would have occured (burned steel etc.) the savings would have been minimal.

    Adding to the fine points made by you gentlemen, there is of course the lack of metallurgical understanding back in the day. As Mike rightly points out, today we have a great understanding of what elements do to the properties of steels, and how to work them. This knowledge though was mainly discovered in the later C19th and C20th. Back in the days of blister, shear and crucible steel, steel was not very consitent; Alex Bealer talks about smiths testing individual batches of steel and he writes from smiths who worked in the 20th century. Today if I wanted to make a planeiron from A2 or 1095 or whathaveyou I would look up the very accurate specifications for that steel; I would get a datasheet telling me what temperature to quench the planeiron and in what medium, and I could look up what temperature to temper it for a specific HRC. Not so back in the day. It would have been much more reliable to lay on a steel edge and have the iron body back it up or act as a shock absorber.

    Comment by Matt — June 27, 2008 @ 4:20 pm

  6. Matt,

    Thank you so much for this post, there is a gem of information in there I have been looking for, the difference in the price of iron and steel during the period of interest! I have been searching for prices of iron and steel, but lacking a per pound price, your ratio of steel being 5 times the cost of iron, gives me the information I wanted. I am still curious as to the actual prices to compare to the prices/costs during the mid nineteenth century.

    Again, thanks for your comment.

    Stephen

    Comment by Stephen Shepherd — June 28, 2008 @ 6:58 am

  7. […] the recent comment made by Matt on Laid Steel Blades giving the value of steel as being 5 times that of iron at the time of the American Civil war, got […]

    Pingback by Full Chisel Blog » Price of Iron and Steel in the Nineteenth Century — June 28, 2008 @ 8:55 pm

  8. I realize that this is a late date to add to this discussion, but in case anybody reads this: The best layman’s reference to heat treating steels is by William Bryson “Heat treatment, selection and application of tool steels”. Generally, a steel will be quenched in whatever medium will provide the fastest quench without setting up stresses that crack the steel. “W” series steels can handle a brine quench, while “O” (oil) or “A” (air) steels will crack in a water or brine quench – I’ve done it a couple of times. Attempting to use any tool without tempering leads to crumbling or cracking of the edge, sometimes even when sharpening. Tempering for several hours at a relatively low temperature (300-350 F) completes the conversion of the steel crystals and reduces stress in the steel, to give a durable, yet very hard edge. Cryogenic tempering tweaks the last little bit of crystal conversion. The difference in blade performance between a low temperature long soak tempering in your kitchen stove oven and the usual home blacksmith’s “reheat to a certain oxide colour and quench” type of tempering is significant. I usually anneal, then harden and temper new blades, because few come correctly heat treated – generally way too soft. Even big box economy chisel lines are made from good steel poorly heat treated. Redo one of these and you’ll have a superior tool for few $$. My favorite blades are thicker laminated ones. The heavy layer of soft steel or iron dampens vibrations nicely.

    Comment by Geo — October 5, 2008 @ 8:46 am

  9. Geo,

    Never too late, and as you may have noticed the current post is about laminated chisels. Thanks for the information and your comments.

    Stephen

    Comment by Stephen Shepherd — October 5, 2008 @ 6:10 pm

  10. Hello:

    I enjoyed reading the several comments regarding plane blades and “hardening”. My quest was for information on case hardening a set of blades for a Stanley 45 molding plane. It had been suggested to me that the blade I recently sharpened which was done firstly with a file, then with stones was not very hard. So that it may not have been tempered. (I can see the colors starting at the sharp end with blue and ending about 2 inches up the blade with “straw”.)I had assumed it was tempered. It was suggested that it may have been case hardened. So, being a novice in metallurgy, I am looking for some information on old Stanley 45 molding plane blades. Do you think they were tempered or case hardened? Does it make sense to try to case harden or retemper that blade?

    Regards,

    john murphy

    Comment by john murphy — December 6, 2009 @ 3:40 pm

  11. John,

    The problem with case hardening is that it can’t be sharpened, the hardness is on the surface and any abrasion you are back to un-casehardened steel.

    I have owned a 45 and a couple of 55’s, but sold them, I always thought the blades were not as hard as other plane blades, especially laid steel blades. The advantage of softer blades is that they are easier to sharpen but don’t hold an edge well. I did use the Stanley’s and thought that they worked fine for what they were. I think they are trying to do too many different jobs, none of them very well. I think it is a trade off in that it will do a lot of things and some of those blades the only way a craftsman could sharpen them is with files, so they are hardened but then tempered to soften them up.

    Stephen

    Comment by Stephen Shepherd — December 6, 2009 @ 6:01 pm

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