Answer
Oct 25, 2022 - 05:36 PM
Q - If I was to hand block steel or alum, what grit stone would leave a roughness value in microinches between 20-40 RA grinding wet?
A - RA surface roughness rating in microinches is not typically used as a reference in the knife sharpening community. If you were to, for discussion sake, compare it on average in micrometers (microns are typically used in the knife sharpening community) then about a 100 grit abrasive would likely give you a RA of 20-40 microns/micrometers.(30 microns is about 1200 microinches) That could also be different, depending on if the abrasive is plated or resin/magnesia/metallic bond based. In knives, the steel type and carbide volumes also make a considerable difference. It also depends on steel type vs abrasive type. For example, aluminum oxide stones does not cut high vanadium carbide steels as well as diamond or CBN stones.
For the sake of discussion and if my calculations are correct and using your example then 30 microinches grit size would equate to approximately 0.8 microns. This would be about a 10,000 grit JIS / 2,000+ grit Fepa-F stone particle size. As for the actual surface finish on a blade edge, it would depend on many factors.
You can use the Gritomatic grit chart for reference to convert grit between different ratings and manufacturers. Link below:
https://www.gritomatic.com/pages/grit...
A - RA surface roughness rating in microinches is not typically used as a reference in the knife sharpening community. If you were to, for discussion sake, compare it on average in micrometers (microns are typically used in the knife sharpening community) then about a 100 grit abrasive would likely give you a RA of 20-40 microns/micrometers.(30 microns is about 1200 microinches) That could also be different, depending on if the abrasive is plated or resin/magnesia/metallic bond based. In knives, the steel type and carbide volumes also make a considerable difference. It also depends on steel type vs abrasive type. For example, aluminum oxide stones does not cut high vanadium carbide steels as well as diamond or CBN stones.
For the sake of discussion and if my calculations are correct and using your example then 30 microinches grit size would equate to approximately 0.8 microns. This would be about a 10,000 grit JIS / 2,000+ grit Fepa-F stone particle size. As for the actual surface finish on a blade edge, it would depend on many factors.
You can use the Gritomatic grit chart for reference to convert grit between different ratings and manufacturers. Link below:
https://www.gritomatic.com/pages/grit...
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