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  1. #61
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    Quote Originally Posted by rob streeper View Post
    Hi Luke,

    I may down the line but those subjects are pretty touchy in these parts.

    At this point I'm looking to determine what the characteristics of commonly used lines of chisels are and from that try to infer the answers to questions such as:

    1) How hard is hard enough?
    2) How hard is too hard or soft?
    3) Which lines of chisels have better and worse reputations?
    4) What characteristics do consumers want in chisels?

    It's apparent that megalothymia (https://en.wikipedia.org/wiki/Thumos) is prevalent in woodworking too i.e. everything must be the hardest, sharpest, most expensive etc. But is super-hardness really necessary or desirable?

    Considering my studies of saw blades I can see that acceptable hardness encompasses about a 10 HRC point range, 20 points if Footprint saws are considered hard enough.

    Cheers,
    Rob
    Hi Derek,

    As I wrote in my response to Luke (@#3 above) I'm trying to get an idea of the characteristics of other chisels for my purposes. I'm not trying to create a definitive all encompassing survey of chisels generally.

    Regards,
    Rob
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

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  3. #62
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    Quote Originally Posted by Bushmiller View Post
    Derek

    How's your Japanese?

    Attachment 427019

    This is a set Rob bought from me. I suspect they are from the lower end of the market purely on the basis I was able to afford them in the first place, but I don't recall exactly what they cost. Other than that I have no information on them. One of the JP specialists may be able to identify them.

    I have taken the liberty of showing the pic here because I have it and as Rob is dealing with a big freeze way down in Texas.

    Regards
    Paul
    I have the same set. According to the ebay ad the brand is "Na" and they cost me USD220 for the set of 10 about 5 years ago. No luck trying to find them again.

  4. #63
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    Quote Originally Posted by rob streeper View Post
    Must say that I'm surprised that the fishtail has such a low temper. Typically they are pushed, not struck, and used without leverage, so can take a much higher temper.

    Sent from my ZTE T84 using Tapatalk
    Stay sharp and stay safe!

    Neil



  5. #64
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    Quote Originally Posted by NeilS View Post
    Must say that I'm surprised that the fishtail has such a low temper. Typically they are pushed, not struck, and used without leverage, so can take a much higher temper.

    Sent from my ZTE T84 using Tapatalk

    Higher than HRC 65 for a steel chisel? I know that some of the cobalt alloys such as M42 and the tungsten T alloys can be somewhat harder, up to ~HRC 70, but my understanding is that > HRC 70 is where the tungsten carbides start.
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  6. #65
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    Quote Originally Posted by NeilS View Post
    Must say that I'm surprised that the fishtail has such a low temper. Typically they are pushed, not struck, and used without leverage, so can take a much higher temper.
    I think I understand what you are saying -- but as a maker why would you bother?
    If you are set up and experienced with making chisels that are struck and therefore need to be at least a little bit ductile, why would you change steels and processes -- to make a less ductile chisel -- for what is essentially a small volume product.
    regards from Alberta, Canada

    ian

  7. #66
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    Quote Originally Posted by rob streeper View Post
    Higher than HRC 65 for a steel chisel? I know that some of the cobalt alloys such as M42 and the tungsten T alloys can be somewhat harder, up to ~HRC 70, but my understanding is that > HRC 70 is where the tungsten carbides start.
    Rob - my understanding is that some high carbon Japanese steels such as Shirogami 1 and Tamahagane will go 65+ HRC, for example Iwasaki's razors went up to 67 HRC, but as Ian points out most blades, and in particular those that will be struck, would be too brittle in that range, so blacksmiths remain in their comfort zone where they do most of their work. Sadly so, as a well made fishtail in Shirogami 1 or Tamahagane at HRC 67 would be a beautiful tool to use.

    Quote Originally Posted by ian View Post
    I think I understand what you are saying -- but as a maker why would you bother?
    If you are set up and experienced with making chisels that are struck and therefore need to be at least a little bit ductile, why would you change steels and processes -- to make a less ductile chisel -- for what is essentially a small volume product.
    Stay sharp and stay safe!

    Neil



  8. #67
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    The two sets of Japanese chisels I've tested both have steel/iron hooped handles for hammer use. I do have another set of dog-leg chisels with the longer push style handles but haven't tested them yet.
    During my experiments with saw steel I was able to over-harden 1095 to the point that it shattered under the indenter of the hardness tester. IIRC I was austentizing at ~1650-1675 oF / 30 min and quenching into NaNO2/NaNO3/H2O at ~400 oF. Quite spectacular little explosions with the resulting fracture patterns looking just like broken glass. Some of the pieces appeared to show hardnesses above HRC 70 before they let go because the indicator would sometimes settle for just a moment before failure. Might have made good razors but I doubt that they'd have held up in any application where real force was applied.
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  9. #68
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    Default Revised and expanded limiting slopes analysis of New Age and Ames Superficial Testers

    I've added additional data to the New Age MRBR-DI tester results in the form of measurements of the HRC 46.1 standard block. Please note, the reported HRC values are RAW values, i.e. uncorrected for slope and offset. When I report HRC values for my measurements of tools I always correct the reported values.

    These are the results, using the same blocks as for the New Age tester, for the Ames 2-S superficial hardness tester. These results are converted values from HRN45 measurements to HRC but they are not corrected for slope or offset.


    In a nutshell, the New Age results are + 0.41 HRC units and those for the Ames superficial hardness tester are + 0.25 HRC units at HRC 60. I'll do the Ames 4 and the HR-150A next.

    As shown in this example, NIST transfer standards generally can have uncertainties of 0.2 HRC or less.


    Unfortunately Transfer Standards are ~$1350US each and you need three. I think + 0.5 HRC units accuracy (or a little less) for measurements of woodworking tools is more than adequate.
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  10. #69
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    Quote Originally Posted by rob streeper View Post
    During my experiments with saw steel I was able to over-harden 1095 to the point that it shattered under the indenter of the hardness tester. .... Quite spectacular little explosions with the resulting fracture patterns looking just like broken glass. Some of the pieces appeared to show hardnesses above HRC 70 before they let go because the indicator would sometimes settle for just a moment before failure. Might have made good razors but I doubt that they'd have held up in any application where real force was applied.
    From the little I known, that is what I would expect with a high carbon/low impurities steel; it will take a high brittle hardness but at the expense of toughness & ductility. Common knowledge I'm sure among those following your thread, Rob.

    I had one very old Tamahagne blade which was extremely hard (just a relative judgement on my part, not a measure) and it was in a class of its own. Took a superior edge, but so brittle that it developed some very fine cracks running back from the edge. Not an issue because the soft iron backing held it together.

    If you are just hand pushing a blade, and not using a lever action, it may cope with that level of hardness, but drop it, and yes, it will shatter. I've experienced that a few times on less expensive blades that I have not been so careful with. Also with some of the cutting tools I've made myself.

    Anyway, following your thread with interest.








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  11. #70
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    Thanks for your comment Neil, always good to have input on the project. Inspired by your reference to the Japanese tamahagane I found some references that have pretty well anatomized Japanese tamahagane/shingane blades and their processing.

    Remarkable accomplishment for the time but time marches on and modern technology can do better.
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  12. #71
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    Quote Originally Posted by rob streeper View Post

    Remarkable accomplishment for the time but time marches on and modern technology can do better.
    That puts it into perspective, Rob.

    Given that, the modern equivalent is more economical by a long way.



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  13. #72
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    The soft part of the Japanese style chisels is often referred to as 'iron' but I haven't found an analysis such as for the above Inoue citation.
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  14. #73
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    Quote Originally Posted by rob streeper View Post
    The soft part of the Japanese style chisels is often referred to as 'iron' but I haven't found an analysis such as for the above Inoue citation.
    Typically the jigane is just old western cast iron. They love old anchor chains and the like that were cast well over 100yrs ago. When the bevel is sharpened it will often reveal the flow pattern from the original pour.

    The softer, the better, to absorb any shocks that would crack the jigane.

    It is the same reason why I like my woodturning lathes to be cast; they do a better job of absorbing any vibrations.

    The old cast iron may also be better for fluxing the jigane to the higane.

    Sent from my ZTE T84 using Tapatalk
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    Neil



  15. #74
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    Quote Originally Posted by NeilS View Post
    Typically the jigane is just old western cast iron. They love old anchor chains and the like that were cast well over 100yrs ago. When the bevel is sharpened it will often reveal the flow pattern from the original pour.

    The softer, the better, to absorb any shocks that would crack the jigane.

    The old cast iron may also be better for fluxing the jigane to the higane.
    Not to nic-pic, but my understanding is that Japanese edge tool makers seek old WROUGHT iron. And the "flow pattern" is actually from the rolling and hammering process use to make the wrought iron.

    I also understand that after about 1890, the process of making wrought iron changed enough to make the more recent iron less attractive to Japanese smiths.
    regards from Alberta, Canada

    ian

  16. #75
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    Ian, I suspect the technological transition you're referring to is known as puddling. https://en.wikipedia.org/wiki/Puddling_(metallurgy)#
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

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