found a catra/hardness test of kitchen knives

Discussion in 'The Kitchen Knife' started by inferno, Oct 18, 2019.

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  1. Oct 18, 2019 #1

    inferno

    inferno

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    you will have to translate it from swedish https://www.testfakta.se/sv/hem-hushall/article/strid-pa-kniven-om-vilken-som-ar-bast-i-test

    pdf https://www.testfakta.se/sites/default/files/2019-08/Grafik_ny(190828).pdf

    the interesting parts are the hrc test and and the catra test.
    Skärpa nyskick / återskärpt - thats the first 3 catra cycles, factory edge / resharpened blade.
    Slitagetålighet, totalt skärdjup - total mm of papers cut with a factory edge.

    Now they did not manage to "resharpen" the blades so they actually cut better/more than factory. which is quite odd to say the least...
     
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  2. Oct 18, 2019 #2

    ModRQC

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    The more I read - and this was unexpected - the more Victorinox knives have something to say. Shouldn't they go higher end stuff than their present offer, or is it after all simplicity which makes them so nice, if far from perfect according to the "vibe" online about them being good, but only so and never that sharp as J knives or even some german knives OOTB or after sharpening.
     
  3. Oct 18, 2019 #3

    RDalman

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    I feel very sceptical to this lab. How did they take one reliable hrc-test for example, since none should have paralell flat surfaces, and especially how did they test the yaxell. And then obviously they're not great at sharpening, I wonder about their definitions of sharp and how they percieve things.. It's probably fairly different to us on this forum. Example funny they say the mora have a sturdy blade, when it's a 2 mm thin thing I would classify as a laser.
     
  4. Oct 18, 2019 #4

    suntravel

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    It is possible for example with an Equotip 550 Portable Rockwell tester

    Regards

    Uwe
     
  5. Oct 18, 2019 #5

    RDalman

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    That's a "translated" bounce test right? Not a very accurate rockwell test no?
     
  6. Oct 18, 2019 #6

    suntravel

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    No bounce but only 50N force +-1HRC accurate, like normal testers also, but way more expensive.

    Regards

    Uwe
     
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  7. Oct 18, 2019 #7

    inferno

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    i have no idea how they tested the hrc but this is a service that they offer and i would guess they know what they're doing. here is a recent test report.
    https://knifesteelnerds.com/wp-content/uploads/2019/10/CATRA-Update-9.25.19.pdf they seem to have 0,5 HRC resolution on their machines.

    regarding the sharpening. heheheh yeah. I wonder how hard it would be to outperform any factory edge?
    not very hard at all in my experience. they obviously dont know how to sharpen correctly.
    no mention about how it was sharpened nor what equipment was used for this. could be a random brick for all we know.

    Still data is data.

    the yaxell seems suspiciously soft for being a fairly well regarded japanese brand. the mora is most likely 12c27 or even 12c27m and they manage to cram out 58,5 hrc out of that one. thats quite good for being mass produced imo. I dont know how hard you can actually get that steel if you really wanted but it can't be much higher than that. maybe 60?
     
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  8. Oct 18, 2019 #8

    suntravel

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    Resolution and accuracy are two pair of shoes ;)

    My HRC testing machine has 0,2 HRC resolution, but only +-1HRC accuracy.

    Regards

    Uwe
     
  9. Oct 18, 2019 #9

    inferno

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    of course you are right.

    do you know how accurate you could get with the old machines where you had to judge the area of indentiation optically?
     
  10. Oct 18, 2019 #10

    inferno

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    how good is the repeatability on your machine Uwe, from sample to sample if you do a series of them in quick succession? is it +-1hrc every time?
     
  11. Oct 18, 2019 #11

    Nikabrik

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    In the crowdfunded test, CATRA did a Vickers test and converted to HRC from that. Larrin pointed out that they're conversion is outdated and inaccurate, so actual HRC was around a point higher. That may or may not be the case here.

    I'm surprised to see the Mora hardness so high, since one of their outdoor knives in 12c27 has been tested at 55HRC.
     
  12. Oct 18, 2019 #12

    RDalman

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  13. Oct 18, 2019 #13

    suntravel

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    repeatability on the same probe 0,2 HRC, but what also plays a role is the surface roughness, which could change on the hand grinded knives and do not compare to the polished master for calibrating...

    Regards

    Uwe
     
  14. Oct 18, 2019 #14

    inferno

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    they also did a real hrc test since the conversions are only approximate. you can see this in the pdf. the vickers conversion is several hrc off.
    same if you try to convert from brinell to hrc or hrb. you have to do the real test.
     
    Last edited: Oct 18, 2019
  15. Oct 18, 2019 #15

    inferno

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    could be older stock maybe. i know a few years ago when kj eriksson and frost got merged to mora of sweden then they ran the 12c27 at 56. still it was not that smeary on the stones imo. all the sandviks are quite good in this regard. but you had to sharpen often. i use my moras like 100 times a day so i have to sharpen once a week at least.
     
  16. Oct 18, 2019 #16

    inferno

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    I have read in some older text books that you needed to do 3 indentations close to each other and only the third one would be accurate. eventual dirt would compress etc etc. I guess its a bit different now with modern machines.
     
  17. Oct 18, 2019 #17

    RDalman

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    Well they're not very impressive like that i agree. You could probably re HT them better with your setup since you have the hang of it.
     
  18. Oct 18, 2019 #18

    suntravel

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    my main job is to do process improvements for automotive industry, i can use very modern high end machines to measure my hobby knife making stuff :D

    Regards

    Uwe
     
  19. Oct 18, 2019 #19

    inferno

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    I could probably not keep a steady temp. since i guess these needs at least 3 minutes soak or so. but i have not really tried either. I have some probes i could stick in the "forge" to test it next time i HT something.
     
  20. Oct 19, 2019 #20

    Sharpchef

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    Catra testing is perfekt for guys that cut paper the whole day... me not.

    Koraat (austrian Bladesmith) made me some knifes years ago... 1 in 1.2562 and the other one in self melted Niob alloyed steel with high carbon but nothing else...

    The self melted one could cut heavy paper about 3 times longer then the tungsten alloyed 1.2562... In the kitchen the Niob steel just takes an amazing edge within seconds but loose it quite soon.... The other one cuts, and cuts and cuts.....

    The main problem with testings like this is we got in edge retention tests: The user`s cutting technique, the ingredients and of course the used cutting board could hardly be tested to get results counting for everyone.

    We could do tests like i did (but it takes enourmous amounts of time to do this only for one steel and the most important thing, the kind of sharpening level (angle, grit of stones, technique....)

    I needed about 1 year for one knife (so only one steel) in pro business (cooking in a school daily and in a a la carte hotel in the evening) with only one sharpening angle to get some "valid" results....

    The testing was more like handsharpening VS 2 different Jiig`s (sorry, but regular edge retention testing needs to be done with items like this....)

    The handsharpening results can only be seen as an overview what different finishing stones can do. The Jiig testing was obvious a little bit easyier because of an constant angle.

    I can post the results if you like. But it was only for 1.2562 steel at 66 HRC, with this knife with Chosera 5k VS 10k Finish by Hand, 10k finish with EP VS Bogdan sharpening system (pressure control!) . And my favorite option Bogdan System with very high end Finish 30k + Nakayama (at least for this steel.

    Greets Sebastian.
     
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