80 CBN vs 60 grit AlOx

John K Jordan
>>>...have shaped tools on the 80 grit CBN, and didn't like the fact that is was slower than my 60 grit Norton blue wheel.

I've done heavy shaping of HSS tools on an aluminum 80 grit CBN from Rizza. I found it perfectly acceptable. Two points to consider:

One, I didn't do a direct comparison with a 60 grit AlOx but the CBN was no slouch. I have no idea if it took longer than the convention wheel but even if it did, I don't do such shaping every day.

Two, I find value in a few things about the CBN - it never needs dressing, it never changes diameter, it always runs true without any vibration, it throws far fewer sparks, and unlike conventional wheels it can't shatter or explode.

A few downsides to the CBN: the cost is higher, it can load up with heavy grinding of mild steel (the reason I keep two separate grinders with conventional wheels), and it's not much good for identifying types of steel with the "spark test".

Note: For those unfamiliar, the spark test can help distinguish between low carbon, high carbon, HSS, cast iron, stainless, and titanium. I mostly use it to test steels found around farms and old homesteads to see if they are true wrought iron. I have a few buckets full now, valuable to blacksmiths and no longer produced.


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