Takamura R2 Gyuto 210 mm

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kwakster
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Joined: Thu Jul 27, 2017 8:46 am

Takamura R2 Gyuto 210 mm

Post by kwakster » Sat Sep 15, 2018 1:08 am

Right hand Takamura R2 Gyuto 210 mm from a local Chef, who got it as a birthday present from his wife.
The knife has already been used for two months in the commercial kitchen and it was time for it's first resharpening, which i did yesterday on a Paper Wheel with 15 micron diamond compound and then deburred on a second Paper Wheel with 0.25 micron diamond compound.
The idea was to make an edge that would do both slicing & pushcutting well, and also to remove as little steel as possible from the fine and thin R2/SG2 blade @ 63-64 HRC.
The new edge measures +/- 20 degrees inclusive and can whittle a chest hair from root-to-tip at about 4 centimeters from the point of holding, and after a few test cuts into a old piece of beechwood cutting board.

I took these pics with an old Ipad and actually wanted to erase them again as being not good enough until i enlarged the last picture twice.
At first i thought i saw small dirt spots on the new bevel, but those tiny white specks were actually the sliced off peaks of the micro-dot structure on the inside of the flimsy plastic blade protector sleeve.

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kwakster
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Re: Takamura R2 Gyuto 210 mm

Post by kwakster » Sat Sep 15, 2018 1:09 am

The owner of the Takamura R2 just sent me the link to this clip, in which he uses a grape to test the new edge:

https://m.youtube.com/watch?v=ID9KZW0d9 ... e=youtu.be

Sean-in-AK
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Location: Juneau, AK

Re: Takamura R2 Gyuto 210 mm

Post by Sean-in-AK » Sat Sep 15, 2018 1:53 am

What is a paper wheel?

Nice video, the knife looks fabulously sharp.

kwakster
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Re: Takamura R2 Gyuto 210 mm

Post by kwakster » Sat Sep 15, 2018 2:26 am

A Paper Wheel is a lightweight disc made of industrially compressed paper/cardboard that is used on an ordinary bench grinder.
A standard set consists of a sharpening Wheel which uses a layer of black silicon carbide powder (covered in a layer of wax for cooling your edge during sharpening), plus a deburring/polishing Wheel on which you use a supplied block of white aluminium oxide (this Wheel has slots in it's rim that work like a fan when in use, and thus provide for a continuous stream of cooling air on your edge during the deburring/polishing process.)

Now the word "bench grinder" in combination with sharpening quality knives made me cringe when i first heard of it, but when i bought my first set from the US back in 2009 and started using it i soon found that it actually works very gently when used correctly.
Later i bought several "naked" Wheels to use with various diamond powders & compounds.
Most people use Paper Wheels only on cheap knives for a quick edge, but with some practice they can also be used with good results on better quality knives.
This very long thread on Bladeforums.com in the US will provide lots of reading material if you're interested:
https://www.bladeforums.com/threads/pap ... ou.578787/
Last edited by kwakster on Sat Sep 15, 2018 7:51 am, edited 1 time in total.

Sean-in-AK
Posts: 66
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Re: Takamura R2 Gyuto 210 mm

Post by Sean-in-AK » Sat Sep 15, 2018 2:45 am

Thanks for the link. I will have a good read with my morning coffee tomorrow. I really enjoy learning about various tools and techniques.

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ChefKnivesToGo
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Re: Takamura R2 Gyuto 210 mm

Post by ChefKnivesToGo » Wed Sep 19, 2018 3:08 pm

Looks sharp to me. I hope you're enjoying that knife. It's a good one.
Mark Richmond
Co-Owner Chefknivestogo
https://www.chefknivestogo.com

kwakster
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Re: Takamura R2 Gyuto 210 mm

Post by kwakster » Sun Feb 03, 2019 8:28 am

Update: according to the Chef this edge done on Paper Wheels lasted him 2 months in his commercial kitchen, which was just as long as the factory edge had lasted him.
During that time he sometimes touched up the edge by stropping it on an MDF strop with 1.0 micron diamond compound until that no longer worked satisfactory (in the last week or so), after which he used a fine ceramic rod on it.
Differences with the factory edge were that the Paper Wheel edge had a slightly smaller edge angle (+/- 20 degrees inclusive instead of +/- 22,5 degrees inclusive), was finer polished, and had a higher sharpness.

We're still in the process of finetuning the edge to his specific requirements, and next time he brings in the knife it will probably get a little less refined edge to see if it's useful life can be prolonged a bit more.
In his kitchen the real edge killers are the mandatory plastic cutting boards which are very abrasive on knife edges, together with the almost unavoidable tiny sand particles which sometimes remain in the huge quantities of vegetables that need to be processed.

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lsboogy
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Re: Takamura R2 Gyuto 210 mm

Post by lsboogy » Sun Feb 03, 2019 1:44 pm

Nice edge - you have mechanized Murray Carter's newspaper strop. Sounds like the chef has a fine sharpener to go to. My question would be what happens if he chips the knife - you might need to go to something a bit more in the 20-50 micron range. The machinists at my workplace use grinders to do their tools as well, but I have given a couple of them a 12K stone and a leather strop with 0.5 micron chromium and 0.25 diamond paste - you should advertise your services a bit - machinists need sharp tools (if you are in an area with aerospace folk they pay well and use the highest end tooling possible - including tools with HRC of 70+). The pastes work well for them, as do the stones. If they had a place to send stuff for better grinding they probably would do it - as is they take care of their own tooling. You might well have a career that pays well if you can find the work kwakster, some tooling that they work with is very expensive custom stuff - Scotty was pissed at me because I had him burn a $1500 custom bit a few years ago - why I gave him the stone and strop. Aerospace stuff can be outrageous in pricing because of the nature of our work -

kwakster
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Re: Takamura R2 Gyuto 210 mm

Post by kwakster » Mon Feb 04, 2019 7:27 am

I had not heard of Murray Carter's newspaper strop, but from what i could find on the internet he doesn't seem to use diamonds or oil for his method.
For me it's the combination of cardboard, diamonds, oil, and speed which makes sharpening & polishing so effective.
The cardboard holds the dried oil on it's surface (and also some liquid oil in it's top layers) which holds the diamond particles (even at speed), and during operation both the edge apex as well as the small diamond particles themselves are protected from overheating by the oil.
The type of oil also plays a significant role in the process, as it both protects the diamonds from premature wear and also makes them cut cleaner noticeably, which translates into less burring.
I can reprofile, sharpen, and deburr an S35VN Sebenza using only a Paper Wheel coated with 15 micron diamond compound (diamond paste mixed with specialty oil)
(to be honest: so far this is the only steel with which this works, but i intend to keep tinkering)

For removing chips in edges as well as hollowed out edge sections i currently use the side of my Tormek SB-250 Blackstone (black silicon carbide @ about 1000 grit) running slowly in water with a bit of detergent in it (to avoid glazing)
I'm however thinking of replacing this stone for one of the new Tormek diamond wheels, as these are diamond coated on the rim as well as on one side.

Le me know if you have a job opening, i might even consider coming to the US if it pays the rent, :mrgreen:

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lsboogy
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Re: Takamura R2 Gyuto 210 mm

Post by lsboogy » Mon Feb 04, 2019 7:40 am

My company definitely pays the rent, but almost all the positions here require US citizenship - we do have a German and a couple Brits working here, but I know it was a pain. Sent you a pm with company info - take a look - can't hurt

Back to the gist, I'm always worried that a mechanized system will heat up a blade locally - causing soft spots on the knife - why I use whetstones to do my knives. But I would guess that a stropping would not heat up the blade too much - glad to see there are those coming up with such things.

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