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I Forge Iron

Knife Class Log 107, Sharpening


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Could you elaborate a little?  What's the danger or down side of using one of these CBN wheels on mild or medium carbon steel?  I don't know much about them, but a quick look had me thinking they might be worth the investment.   However, if they shouldn't be used for general purpose grinding I wouldn't want to spend that kind of money on them.

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The Radius Edge wheel is 8" in diameter and has a 5/8" arbor hole.
  1. Diameter = 8"
  2. Wheel width = 1.5"
  3. Arbor hole = 5/8"
  • CBN (cubic boron nitride) grinding wheels are state-of-the-art for grinding high-speed steel tools
  • These wheels are designed for use with bench-type grinders. 1800 rpm or 3600 rpm
  • Perfect for sharpening woodturning tools (high speed steel)
  • Provides a superior edge compared to the old stone wheel
  • Balanced – does not require "truing" 

These wheels will change the way you sharpen forever – Think razor sharp edges.

CBN or Cubic Boron Nitride grinding wheels are designed for sharpening high speed steels only and should not be used for other applications. These wheels have a 1.5" face so they are easy to use and work well with the Wolverine Sharpening System. The 180-grit wheel puts almost a mirror finish on your edges and makes them "scary sharp."

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Another commercial source notes "CBN Grinding Wheels are designed to be used to sharpen hardened Steel or Carbide. Sharpening non-heat treated steel, aluminum or other soft metals will damage the CBN Grinding Wheel."

Other sources note that it is intended for hard materials (glass, carbide, hardened steel, etc). I'm suspecting that softer materials will gum up the wheel and reduce its effectiveness.

Addendum: here's an article from a woodturner about his discovery of CBN wheels and discussion of their uses. Looks like I was right about softer materials gumming up the surface, but he has recommendations on what to do about that: https://www.robohippy.net/featured-article/

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Makes sense.  Thanks for doing the leg work (or finger work as the case seems to be) on this.  They still might be worth the investment, but I was really hoping to get rid of the other wheels forever without losing any capability.  It doesn't appear that's an option yet.

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  • 7 months later...


How do you guys grind your secondary bevels after HT? I'm thinking about buying whetstones to go from no edge at all to "papercutting sharp", but what grits should I use? I've learned that a stone in the 180-240 (or even lower) range will create the edge, but I don't really know how big the gritsteps should be after that. Should I buy something like two two-sided whetstones, a 180/400 and a 1000/3000? Or should I skip the 3000 and strop on a leather belt instead? Replace the 400 with a 600 side? I really have no clue.

One thing that's annoying me is the fact that the extremely low grit stone would solely grind secondary bevels on newly forged knives, and on nothing else. The other grits above will probably get used more in the kitchen or just general knife repair. It just feels weird having a stone that gets used very little, but is it true that you can use lower grit stones (120-240) as a flattening stone for the other stones?

I love this hobby but just can't seem to figure sharpening out, no matter how many hours I've spent researching this on the internet. I'd be very happy for all the help I can get.

// Gustav

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