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Thread: Plane Blade Hardness

  1. #1
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    Plane Blade Hardness

    A number of years ago I tuned up a Stanley 60 1/2 purchased from Home Depot and bought a Japanese laminated blue steel blade from Japan Woodworker to fit it. It worked exceedingly well after that and seemed to hold an edge forever.

    However I had always wanted a LN or Veritas so gave the Stanley to my son thinking that now I can replace the old Stanley with what I really would like.

    Now while researching to make a purchase of a new plane, I'm finding that the Rockwell rating of the Japanese blade is 66; quite a bit higher than the Rockwell 58 - 60 or 60 - 62 of the LN, Veritas, Hock and other blades available for these premium planes.

    I'm wondering if I will be disappointed with the amount of re-sharpening needed on a premium plane in comparison to the Stanley with the Japanese blade?

    Does anyone have any thoughts on the matter?

  2. #2
    I have several LN block planes and I'm satisfied with the edge retention. But I have no comparison to the Japanese blade. If you're not satisfied with the LN blade, buy another Japanese blade.

    In steel, hardness and toughness are in inverse relationship. If they weren't, everyone would make their blades as hard as possible. Different people like different tradeoffs between hardness and toughness. LN has made their choice and the Japanese maker has made theirs. You need to make yours.

    Mike
    Go into the world and do well. But more importantly, go into the world and do good.

  3. #3
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    I worked for many years in a museum,completely by hand. I found that plane irons that would BARELY file with a NEW Nicholson smooth file,held their edges the longest. That means something like Rockwell 55,or a bit lower. There is a trade off in hardness and toughness,like Mike said. hardness decreases the ability of an edge to hold,because the tiny cutting edge breaks off.

    I am aware that some iron makers make their irons up to 60 R.C.,but tool steel books will tell you that 60 RC for 01 steel is really pushing it for durability.

    I have also found that if I make an 01 knife,and draw it to 60 RC,it just doesn't hold an edge long.

    I have a Lee Valley laminated Japanese kitchen knife. It has a very hard high carbon steel lamination in its center. The other night I was slicing up tomatos,so I got that knife,and honed it razor sharp so it would cut the skins easily. That knife will take quite an edge! After I had cubed up 2 tomatos,and was using a wooden cutting board,and was careful to not unduly rub the knife on,I found that the super sharp edge was gone enough to not easily cut the tomato skins easily. I wear a wide,harness leather belt 1 1/2" wide. I pulled it out some,and stropped the knife several times to restore the edge.

    I was surprised that the knife edge didn't hold up better. And,it wasn't a real thin edge angle. Nor do I ever use hot water to rinse it,or leave it(or any knife) wet.

  4. Hardness is one of several factors that effects blade performance. Alloy and heat treatment must be considered. We've hardened our blades, both O1 and A2, to Rc62 from the beginning and have never had any complaints about them being too hard. IMO, Rc55 for a plane iron is much too soft for plane irons. Yes, you can file it (barely), but it won't hold an edge long compared with harder steel.

    Which "tool steel books" are you referencing that "tell you that 60 RC for 01 steel is really pushing it for durability"? I've not seen them, and they may be referring to applications for tool and die work, or something other than wood cutting edges.
    Ron Hock
    HOCK TOOLS

  5. #5
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    The one in particular I refer to is a new book "The Tool Steel Guide" by Jim Szumera. It is a very useful book .I also have "Tool Steel Simplified" put out years ago by Carpenter Steel Co. I have several other older books on tool steel also. The particular book I refer to was the most informative book I've had in practical information that was useful to me,especially. It is the only steel book I've seen that says that you must temper a blade when it cools down to about 130 degrees F. to get the most life from the tool you are making. I now do that. Yes,the books are for tool and die work. From a standpoint of durability, cutting steel is more of a challenge than cutting MOST woods. SOME,like Ebony,are abrasive,of course.

    I know that 60 RC does not yield as good an edge retention as my many years of experience has shown me with the softer steel blades I have used.

    I am also aware that you make them 60 RC,so I guess we'll have to disagree.



    Honestly,that is exactly what it said,and I have had personal experience to verify it long before that particular book came out. You can buy one from Amazon. I had a Versitron hardness tester,one of the best made,to check my steels by.

    As I said,I made an 01 blade pocket knife at 60 RC,and it just doesn't keep a decent edge compared to others. I need to re-temper it. It was very accurately checked with the Versitron.

    What your customers think about your blades,or ANY other product probably depends upon what they have had to compare to it. If it's been Stanley,or other commercial irons,I'm sure yours did better!

    I was pretty sure I'd be hearing from you!!
    Last edited by george wilson; 02-09-2010 at 12:17 PM.

  6. #6
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    I was hoping for a nice pat answer that would equate Rockwell hardness to how often I might need to resharpen a blade -- but -- I can now see that while blade hardness is a science, how it translates into blade sharpness retention and durability isn't quite so definite.

    As Mike stated, the various plane and blade manufacturers have made their decision on what is the optimum hardness. I'm also very aware that I need to make my decision soon since that little hardware store Stanley with the Japanese blade was used more than all the others I own.

    At the time I bought the blade for the block plane, I also bought one of Mr. Hock's blades for a #4 Bailey bench plane I picked up at a yard sale. While I don't use that plane as much, I must say the Hock blade and a bit of tuning changed it from an OK tool to an excellent tool.

    I appreciate the response of Mr. Wilson's also, who has found that rather than pushing the tempering of tool steel to the maximum hardness, a better approach might be to back off a bit to obtain better durability.

    In my case, after giving my son the little Stanley block plane, I realize it was the most used plane of the several I own. I wasn't all that satisfied with the blade adjustment setup and I broke one when it dropped on my garage-shop concrete floor. So a modern ductile steel or bronze plane would be better for my use.

    Maybe it will be a coin toss whether to go with a Veritas or a Lie Nielsen.

    Thanks again for your thoughtful and helpful replies.

  7. #7
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    Maybe it will be a coin toss whether to go with a Veritas or a Lie Nielsen.
    Loren,

    I notice you are in the Puget sound area of Washington. Lie-Nielsen will be having a tool event in Seattle in a couple of weeks. You could take the opportunity to handle their block planes and give them a test drive.

    I find block planes are more personal in how they fit the hand than a bench style plane.

    jim
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  8. #8
    Quote Originally Posted by Jim Koepke View Post
    Loren,

    I notice you are in the Puget sound area of Washington. Lie-Nielsen will be having a tool event in Seattle in a couple of weeks. You could take the opportunity to handle their block planes and give them a test drive.

    I find block planes are more personal in how they fit the hand than a bench style plane.

    jim
    When the LN tool event was held here in the Los Angeles area, Ron Hock was part of the event. In addition to his blades, he was also offering his sharpening book* and autographed it for buyers (who wanted his autograph).

    I don't know if he'll be at the Seattle event, but if he is, it would be a good opportunity to talk to him in person and try out some of his blades.

    Mike

    *I bought Ron's book (autographed) and found it to be a very good explanation of steel and sharpening. That is, he gives a good explanation of steel, the hardening of steel, and how that affects the cutting characteristics of the blade. He also explains the various angles of blades in planes, such as the "angle of attack", clearance angle, etc. So by the time he gets into the actual sharpening, you understand why he recommends certain sharpening characteristics and techniques. It was also interesting to meet the actual person behind the blades.
    Go into the world and do well. But more importantly, go into the world and do good.

  9. #9
    I mill and then forge my plane blades from 5/16" O-1 starrett steel.
    I use a homemade propane forge, warm oil quench and oven temper to 62 rc. As hard as m2 steel I have.

    This holds an edge very well on hardwoods( over 200 strokes) such as hard maple, burl walnut and ebony. Holds an edge longer than the A2 on my LN block plane. Perhaps it is the starrett quality control.

    You can see my planes at handplane central gallery, russ garcia-lechelt

  10. #10
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    I would be cautious when trying to equate only hardness to how well a blade will perform or stay sharp. The different grades of steel used will all have a different optimum hardness. In addition, there are many ways to get to the same hardness and they will not all provide the same ability to stay sharp.

    The tool steels are in general not a homogeneous structure. They are made up of tempered martensite, carbide, martensite and potentially some retained austenite. Each of these materials have their own hardness. The distribution of these especially the carbides will have an affect on the sharpness.

    The bottom line for me is that the hardness is only one of several factors that are important. I leave the heat treating and blade properties to the experts like Ron Hock or Lie-Nielsen. They have long experience at producing blades that are very good. My woodworking skill is not determined by the hardness of the plane blade but my ability to sharpen it properly and use it properly.

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