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In the Shop => Knife Sharpening => Topic started by: mat450 on August 05, 2019, 03:16:31 pm

Title: Sharpening 420J2 Stainless Knives
Post by: mat450 on August 05, 2019, 03:16:31 pm
I was presented with Various Japanese knives to sharpen the other day and brands included Shun which used 420J2 stainless steel material.  I found it quite tough to grind and burr even after a freshly trued SB-250 wheel.

Question - Would a CBN or Diamond wheel have better grinding abilities with this kind of steel? or should I stick to the SB-250 wheel.

Thanks in advance

Title: Re: Sharpening 420J2 Stainless Knives
Post by: Jan on August 05, 2019, 10:22:17 pm
Mat, the reason of your difficulties is not 420J2 stainless steel but much harder core steel which is sandwiched between layers of 420J2 steel.

Some Shun knives have very hard cutting core, e.g. VG10, which is supported on each side by relatively mild stainless steel 420J2.

For sharpening blades of exotic steels it is good to have the diamond wheel. In some exotic steels they are carbides which have the same hardness as the silicon carbide in SB wheel. Than the SB wheel only abrades the steel matrix but does not cut the very hard carbides.

Jan
Title: Re: Sharpening 420J2 Stainless Knives
Post by: mat450 on August 06, 2019, 01:23:30 pm
That makes complete sense, when I was grinding I felt I was getting nowhere
Title: Re: Sharpening 420J2 Stainless Knives
Post by: Josu V on August 06, 2019, 07:24:37 pm

I completely agree with Jan.

Recently I have sharpen one Kai Shun Premier (VG-MAX) And one Kai Shun Wasabi.
Directly with Diamond wheels. I Start with DF-250 and finish with DE-250. Then, deburr with different leather wheels.

I think SG-250 wheel is to soft for this kind of steels...

Regards
Title: Re: Sharpening 420J2 Stainless Knives
Post by: Ken S on August 06, 2019, 08:51:10 pm
In fairness to the SG wheels, they were never designed for "exotic" steels. Most woodworking tools were, and still are high carbon steel. Kitchen knives and most pocket or sheath knives are either high carbon or stainless steel.

My question for the farmers market sharpeners: How many of the knives you sharpen are xotics and how many are within the SG range?

Ken
Title: Re: Sharpening 420J2 Stainless Knives
Post by: Josu V on August 07, 2019, 01:31:56 pm

My question for the farmers market sharpeners: How many of the knives you sharpen are xotics and how many are within the SG range?

Ken

Probably none...
Title: Re: Sharpening 420J2 Stainless Knives
Post by: mat450 on August 07, 2019, 02:28:30 pm
I have been up and running for the last 6 months and this was the first time I had encountered 'exotic' knives. They where a mix of Shun and V10 and Vmax blades, but were owned by a chef.  Most of my business comes from kitchens.

I appreciate everyone shedding light on my findings, I want to be prepared for the next time I come accross such knives.  Although its going to be an expensive outlay


Thanks for the advice

Title: Re: Sharpening 420J2 Stainless Knives
Post by: Fernando on August 08, 2019, 04:52:46 pm
I was presented with Various Japanese knives to sharpen the other day and brands included Shun which used 420J2 stainless steel material.  I found it quite tough to grind and burr even after a freshly trued SB-250 wheel.

Question - Would a CBN or Diamond wheel have better grinding abilities with this kind of steel? or should I stick to the SB-250 wheel.

Thanks in advance

420J2 steel is a very soft steel, it is used to make buget knife, this steel is used to make some knives because it is highly stainless

In fairness to the SG wheels, they were never designed for "exotic" steels. Most woodworking tools were, and still are high carbon steel. Kitchen knives and most pocket or sheath knives are either high carbon or stainless steel.

My question for the farmers market sharpeners: How many of the knives you sharpen are xotics and how many are within the SG range?

Ken

In my case, every 100 knives only 2 or 3 are made of exotic steel, and the owners are mostly not chefs, nor are they related to the world of cooking.