# Robin grind-in knife reloaded



## zetieum (Jun 29, 2017)

I have been spending some time in during the last weeks to improve the knife that I made during the Grind-in week-end by Robin @Dalman (see http://www.kitchenknifeforums.com/s...t-grind-in-quot-make-your-own-knife-13-14-may). The knife I was lucky to make was a K-tip guyto, Mizu-honyaki (i.e. water quench with differential hardening). The geometry is a kind of S grind on the left-side and convex right side. 
I was (and still am) very pleased and lucky to have manage to do that in one week-end under the direction of Robin as the first knife I ever made. But the knife was faaaaar from perfect:
- I was too thick behind and above the edge, especially in the middle of the blade
- The finish was not perfect: some low grit marks, the Hamon was visible but not very pronounced
- it was heavily bent, so much that it was almost not possible to sharpen it on flat stones.

I have decided to work on these issues. I though of thinning it and progressively straighten it after thinning steps. My idea was that by removing some steel on the lower part of the blade, that is the hardest, I could maybe release some of the tension that made the blade bent and ease the straightening by having less hard steel handle. So I went through thinning/straghtening cycles. 
- To straighten, I just bent the blade in the other direction until a point I felt it was going to break. I worked pretty well.
- Thinning was done using atoma 400. Never a fun job. I stoped at ~0.15-0.2mm being the edge, 0.6-0.8 at 0.5cm and 1.2-1.3mm at 1cm. At the end I put some convexity to improve food-release.
- Then I refinished the blade using EDM orange stones and sand paper. I then etched the blade in ferric chloride, and sand it. This was done several time to enhance the Hamon. The on the final etch, I finished the bade using a mix of 1000 grit powder mix with some suita powder. 

And here is the result . Much better that what I though I could achieved in all aspects: beauty, cutting performance, and FR. None of this would have been possible without Robin.

it is almost straight: but at this point, it is not a problem anymore.






[video=youtube;0IzM3ZzTvyc]https://www.youtube.com/watch?v=0IzM3ZzTvyc[/video]


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## TheCaptain (Jun 29, 2017)

I'm in total awe! Even under the direction of such a master this is quite an accomplishment!

Did you do the handle as well?


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## zetieum (Jun 29, 2017)

TheCaptain said:


> I'm in total awe! Even under the direction of such a master this is quite an accomplishment!
> 
> Did you do the handle as well?



Thx. Yes. we did the handle during the same week-end. I got some additional tips from Anton who was there


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## crockerculinary (Jun 29, 2017)

wow, very cool. i'm sure that was an awesome experience, and the knife looks great!


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## milkbaby (Jun 30, 2017)

Nice redo! I'm surprised you left the grind in with a fairly warped blade though?

Is the steel 1095 (or UHB20C)?


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## RDalman (Jun 30, 2017)

milkbaby said:


> Nice redo! I'm surprised you left the grind in with a fairly warped blade though?
> 
> Is the steel 1095 (or UHB20C)?



Yea bummer. Finishing that blade was a well informed decision for Mathieu. During the last stages of his gringing it sprung back everything we had straightened during tempering. We only got it straightened halfway back, and it seemed to keep bending back. If it would have been a blade I was working on I would have redone the HT. But mathieu was happy he got through the quench so he wanted to go for it. Great job finishing!


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## RDalman (Jun 30, 2017)

Looks to cut great!! Awesome job!!!


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## zetieum (Jun 30, 2017)

RDalman said:


> Yea bummer. Finishing that blade was a well informed decision for Mathieu. During the last stages of his gringing it sprung back everything we had straightened during tempering. We only got it straightened halfway back, and it seemed to keep bending back. If it would have been a blade I was working on I would have redone the HT. But mathieu was happy he got through the quench so he wanted to go for it. Great job finishing!



Yes indeed, as Robin said, he warned me right after the quench that there was an important risk that whatever we did the blade could be bent. I was aware and took the risk. Not a big risk because I considered that getting a knife out of the week-end was a bonus. I mean: I have knives and can buy some. But spending a week-end seeing, doing, and learning to make a knife was what I wanted to experience.


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## Emskold (Jul 1, 2017)

Cool knife and what a nice hamon. Robin is a awesome teacher!


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## milkbaby (Jul 1, 2017)

Thanks for the clarification, and I defintely identify as warping in the quench is the freaking bane of my existence, grrrr.

Cool project and excellent results! :doublethumbsup:


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## zetieum (Jul 2, 2017)

milkbaby said:


> Cool project and excellent results! :doublethumbsup:



Thanks .


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