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TOPIC: Sharpening chef's knife

Re: Sharpening chef's knife 1 year 2 months ago #8991

  • nicholas6225
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I'm still new at this so.... I don't fully understand the entire theory behind 70/30 grinds but since re-turning my knives back to a 70/30 edge they are insanely sharper and feel as if they stay sharper. The video that made me understand the differences and start to look into it is here

The 70/30 edge is actually ground into the blade when its made/fabricated. I found keeping the factory edge of 70/30 gives me a longer edge retention.

I reassure you the video I posted has lots of information about knife edges and different kind of knife grinds, that'll give you an awesome basic understanding behind knife edge grinds specifically japanese knives.

Hope this opens pandora's box for you
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Sharpening chef's knife 9 months 1 week ago #12659

Hi Gents,

Enjoyed reading your posts on this thread.

I have a similar inquiry....

I have two Mac's - MTH 80 (8") and the MSK-65 (6.5")

What I am trying to figure out is:

1. Would these knives be best for a 70/30 profile?
2. If so, what angle goes on which side?
3. What angles specifically (in degrees)?
4. When giving angles, specify from which perspective (in the vise or in hand) you are assigning to Left and Right sides, please!

Thank you all so much!

Best wishes.
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Sharpening chef's knife 9 months 1 week ago #12670

  • LeoBarr
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It is the first I have heard about the 70/30 profile I have mailed MAC to ask since there is no reference to it on their web site. I recently had to repair a MAC I was given it had a huge chip out of the middle of the blade so it took a lot of work re-profing on a Tormek and then since I am waiting for my WE I put a thinning bevel of 10Ëš to the edge then a micro bevel of 15Ëšwhich I then graduated back in 1Ëš steps to 11Ëšthen I honed it on the Tormek leather honing wheel to remove the steps using an EP using 1200 grit for the 15Ëš bevel and the final bevels.
My experience with any blade except for boning knives or cleavers the cutting edge needs to be as small a bevel as possible try cutting a carrot with a razor sharp axe! So it is vital to have a thinning bevel even my second hand chisel edged Yanagiba has a micro bevel of 30Ëšon it (the main bevel is about 7Ëš).
Hopefully MAC will reply to my mail to confirm or not the 70/30 ratio it does I have to admit look very good on Nick's knives although this makes them right / left handed knives so I hope the users are not both right and left handed .
Here is a picture of my MAC at the tip you can see another bit of the thinning bevel I initially put on with the Tormek since the steel is very hard to work so I thinned the knife freehand on the Tormek before going over it with the EP at 10Ëšetc.
hf0263b0.jpg
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Sharpening chef's knife 9 months 1 week ago #12674

Thanks for the info! Let us know what you hear back from them regarding angles and ratios! thanks!
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Sharpening chef's knife 9 months 1 week ago #12675

  • LeoBarr
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Cutting bevels

Kai Shun 16Ëš
Global 15Ëš

If they are one sided like a Yanagiba or a Deba then the angles are generally double so 30-32Ëšthis is still fine since a lot of European chef knives between 16-18Ëš depending on the thickness and intended use of the blade.
European knives are around 55 Rockwell hardness whereas Japanese knives are 60-65 Rockwell hardness but they require much more disciplined use since they are more brittle.
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Re: Sharpening chef's knife 9 months 1 week ago #12677

  • LeoBarr
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Great link working through the vids now.
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Sharpening chef's knife 9 months 1 week ago #12678

  • cbwx34
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Not having one, I don't know, but one thing you can do is mark both sides with a Sharpie and make some light passes to see what each side is currently sharpened at. This may give an indication as to whether or not the knife you have is asymmetric or not, as well as give you an indication of what angles to use. (This can apply to any knife.)

A web search on the MAC seems to give answers on both sides of the fence... it is, it isn't, it is but doesn't matter, etc. Obviously, if Nicholas took the time and effort to redo it, he can tell the difference. I probably couldn't, or would at least have to have two sharpened different ways to tell what the difference would be, and if it mattered to me. Since my time in the kitchen is minimal... I could probably get away with a 50/50 grind. I've read other chef's who will sharpen 50/50 just for ease of sharpening. Not saying to do this, since undoing it is some work... just a bit of info for the discussion.
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Sharpening chef's knife 9 months 1 week ago #12705

  • LeoBarr
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Thank you for your inquiry. You can use a 70/30 grind if you prefer. However, we recommend 50/50-60/40 for larger knives, 50/50 for paring knives.

Sincerely,



--
Brian Arimoto
Sales Manager
MAC Knife, Inc.
This email address is being protected from spambots. You need JavaScript enabled to view it.
www.macknife.com


FAO Blade & Stone so do the micro bevel(cutting bevel) at15/16Ëšeach side
Last Edit: 9 months 1 week ago by LeoBarr. Reason: adding more info
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Re: Sharpening chef's knife 9 months 1 week ago #12707

  • PhilipPasteur
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Nicholas,

One can not argue with success!!
If you like it, stay with it.

I have decided that I need to make a decision for sharpening a specific knife for a specific use, and knowing all of the properties of the steel on that blade.

My idea on this is this, do what works for you! BUT, there is absolutely no reason that you should be able to get a 70/30 edge more sharp than a 50/50 bevel. If you do, there is something wrong with your technique. Keep in mind that there will need to be adequate thinning behind the edge in any case. Take that as a given, and you really can't make a 70/30% or a 0/30% blade of a given steel any sharper than a 50/50% bevel. The limits are based upon the steel. You cannot exceed the thinness that the steel will support and achieve edge integrity, period.

Often bevel angle is a boutique thing.. The Japanese. according to what there is of the history. made things easy to sharpen, one angle, and flat, Later they made angles more westernized ... easier to sharpen for us bungling western guys ???

My point is, if you can't get a 50/50 bevel a sharp as a 70/30 bevel (within you ability to really determine sharpness... NOT it somehow "feels" sharper), you need to work on your technique!!
Phil

MAX 2001-2013
Hoping there is that bridge!
I miss you Buddy!
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Re: Sharpening chef's knife 9 months 1 week ago #12729

  • LeoBarr
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I think the 70/30 / 60/40 bevels you speak of are recommended for a lot of Japanese knives beveled on each side these bevels are created in two ways it often refers to the number of strokes on the tops to bottom side when sharpening by hand (without the assistance of a tool) and also the bevels will be different angles say 10Ëš on the topside & 15Ëš on the backside .
The video links you gave are very good you may also want to check out "Korin The Chefs Edge" video .
I think this sharpening(hand sharpening) I would reserve either for special knives or for customers willing to pay 20+€ a knife and for single bevel knives such as Debas or Yanagiba .
I do not think I would want to try to sharpen a thick single bevel Deba or a Yanagiba on any tool unless I wanted to introduce a micro bevel which is not how they are intended to be.
I believe that it is important to have many different tools for sharpening commercially since no one tool does it all and for the most part people want is in general a reasonable cheap service although it is good to offer refinements like convex edges etc which the WE achieves quite simply .

The thing with sharpening is its an incomplete subject one lifetime is simple not enough ; that for me is the fascination .

Then of course I keep thinking it is time to make a knife ---and on it goes!
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