Yoshikane SKD Tsushime Tip Bend

Discussion in 'Sharpening Station' started by ared715, Jul 14, 2019 at 5:12 AM.

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  1. Jul 14, 2019 at 5:12 AM #1

    ared715

    ared715

    ared715

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    hey y’all just got off from a crazy busy night. So today our sauté cook thought it would be a brilliant idea to throw a towel at the tall window directly above my prep area to kill a fly...... in the process of retrieving the said towel, my SKD hammered hit the floor and bent the tip about 2mm and at an astonishing 45 degree angle??!!! When purchasing the knife, from the specs and what I’ve gathered through other vendors of this series, is the normal heat treat for these blades is around 63-64 Rockwell and I’m just wondering how the f*ck it didn’t just shatter like all my other similar tippings on various carbon steels I’ve experienced before. In my estimation, though probably incorrect, is that it should have broken before bending to this extreme of an angle... I’m reaching out to y’all before I try and correct it at all whatsoever so any suggestions would be greatly appreciated!!! I have the following tools/stones to fix it:
    1. Table grinder- it has two rotating wheels with a higher and lower grit option....
    2. Sand paper - my brother in law is a painter/carpenter....
    3. Of course my stones ranging from 120 - 8000 grit...
    4. All the usual suspects that a pro carpenter would have.... vice, pliers, files, etc....
    Not sure if this make a difference but I would like to add that this particular example is very very light and thin..... it feels like a pre-laminated blade in terms of rigidity and of course that has its pros and cons. The tip is super thin and ghosts through soft product like a laser and the overall cutting performance is a true laser. I wasn’t at all expecting this when I ordered this knife and it hasn’t gotten a lot of use as I like my Mazaki 240 and 210 kiritsuke, wakui migaki, konosuke GS+ more at the moment... thanks for any info/advice y’all have!! Sorry bout the angle of the photo as it is a bit misleading regarding the thinness of the tip. My iPhone couldn’t capture a straight on spine shot for some stupid reason image.jpg
     
  2. Jul 14, 2019 at 5:24 AM #2

    ared715

    ared715

    ared715

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    image.jpg
    Would also like to add, it’s only exposed core SKD that bent..... this to me is very confusing as I would assume that the 405 stainless cladding would be much more soft and malleable than the core????? If I’m totally off here please correct me because again, I’m assuming. Thanks again y’all! Oh and by the way, the fly got away......
     
  3. Jul 14, 2019 at 4:19 PM #3

    Walla

    Walla

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    Nasty...it's gotta hurt...

    You seem to be taking this very well... don't know I'd have been this calm...

    Afraid I have nothing on terms of advice...

    Good luck...let us know how it works out...

    Take care

    Jeff
     
  4. Jul 14, 2019 at 6:52 PM #4

    HRC_64

    HRC_64

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    I'd personally ask some actual blacksmiths what they would do.if i was on a desert island with professional-grade DIY tools...this is what I would probably try:

    Knipex pliers wrench -or-machinist vise with copper jaw inserts

    Once its close (very. very close) you can think about hammering it dead-flat with apolished, slightly crowned flat face metalworking hammer. I would be very hesitant to go at this home-center grade tools,eg, a generic non-parallel plier, or hardened steel jaws vise, a claw hammer, etc...
     
    Last edited: Jul 14, 2019 at 8:53 PM
  5. Jul 14, 2019 at 7:02 PM #5

    Ryndunk

    Ryndunk

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    My guess is it will break off when you bend it back. Even if it does bend back chances of getting it straight are slim. Probably best to plan on grinding a new tip on the stones/sandpaper. Fixing a broken tip thanks a little work but not to difficult. No power necessary.
     
  6. Jul 14, 2019 at 7:12 PM #6

    JBroida

    JBroida

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    With a bend like that at the tip, being able to straighten it out and not have it break off in the process or shortly thereafter is not a likely outcome. You are better off reshaping the knife to remove that area by grinding along the spine to remove the damage (not the edge at all).
     
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  7. Jul 14, 2019 at 8:14 PM #7

    ared715

    ared715

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    Thanks for the advice y’all! Yeah Jon, that was my thought as well so thanks for confirming! It also has a. Overgrind near the heal so reshaping was inevitable I suppose.... when it comes to reshaping, what happens when I grind past the lamination line where the exposed core steel is shown? How will I know when I’m past the cladding? Feeling when sharpening/grinding perhaps?
     
  8. Jul 14, 2019 at 8:15 PM #8

    ared715

    ared715

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    Or just get a kochi V2 240 when they’re back in stock??
     
  9. Jul 14, 2019 at 8:20 PM #9

    McMan

    McMan

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    Like Jon said, you’re going to attack from the spine down, and not from the edge up. This will maintain edge profile. Once you’ve got the tip re-established, you’ll want to thin in that area.
     
  10. Jul 14, 2019 at 8:30 PM #10

    McMan

    McMan

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    Like this (bad drawing but you get the point):
    tip repair.jpg
     
    Last edited: Jul 14, 2019 at 8:41 PM
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  11. Jul 14, 2019 at 8:49 PM #11

    ared715

    ared715

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    Heard thanks McMan... do you think that I should reshape into a Suji in regards to the sizable overgrind near the back 1/3 of the blade?
     
  12. Jul 14, 2019 at 9:06 PM #12

    McMan

    McMan

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    Turning a yoshi gyuto into a suji? I’m voting no on that one :) I’d just fix the tip and call it a day.
    Can you post a pic of the overgrind?
     
    Last edited: Jul 15, 2019 at 6:11 AM
  13. Jul 14, 2019 at 9:49 PM #13

    ared715

    ared715

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    It’s gonna be hard to capture as I’ve worked extensively to correct it hoping it was just a profile hiccup but the entire flat section in the back half is wonky and was far worse OOTB than it is now... I’ll do my best to capture it ina pic when I get off work tonight! Thanks again for the input/suggestions! I’m glad there’s light at the end of the tunnel and not loosing half of my blade!!!! I think I’ll be able to show the spots better if I sharpen out the JNat kasumi finish I have on there ATM, I used some fingerstones to fill in the gaps but I think if I hit it w my king 800 it should be more evident in pics! Y’all are awesome can’t thank you enough seriously!!!
     
  14. Jul 15, 2019 at 6:00 AM #14

    Carl Kotte

    Carl Kotte

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    I liked this drawing. It looks more like a fish than a knife, but it is very instructive. And the fish looks tasty!
     
  15. Jul 18, 2019 at 10:44 PM #15

    inferno

    inferno

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    yeah just do what the drawing shows. this is what you always have to do to broken/bent tips. I have done maybe 20 of these, and i do this every month on my work moras. If you have any type of abrasive machine to do the heavy lifting you save a lot of time.
     

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