Thread: The science of grit numbers

Searching around google for information on grit numbers, I can only find tables like this -- Grit = Micron = Mesh Conversion Chart

Using a bit of maths, it seems to me that the size of the particles in microns can be calculated by 20'000 divided by the grit number (close enough anyway). Does that sound right?

It depends on whose grit is being considered. Different manufacturers use different scales and so different conversions apply.
In other words, a Norton 8k does not have the same size grit as a Naniwa 8k.
That would be just too easy.

That's a pity. Do you know anywhere I could get data on the various manufacturers?

Originally Posted by smolloy

That's a pity. Do you know anywhere I could get data on the various manufacturers?

It really won't do you any good. The material of the grit, grit size distribution, grit/binder ratio, binder material, all come into play. In the end you just have to see how a stone behaves.

I suppose you're right. Far too many unknowns. Thanks anyway!

Consider the Suehiro 20K with 0.50 micron "grit" size and the Shapton 30K at 0.49 micron. Bluesman hit the nail right between the eyes.


rs,
Tack

We've tried this before and as Utopian says it depends on the data you use, which in turn depends (it seems) on the manufacturer (and perhaps on their marketing division..!)

Just for some interesting reading, take a look at this thread from ages ago. I kinda went a bit overboard for some people's tastes, but perhaps you'll find it interesting...

And a good post about some of the important stuff around the behaviour of stones and grit: http://straightrazorpalace.com/honin...tml#post248353

James.

Thanks Jimbo, that fitting technique was exactly what I did to get my rule-of-thumb formula. The only difference is that I noticed that -0.9 was pretty close to -1, and so I re-did the fit forcing the exponent to be -1. After that I got a numerator of 20k instead of the 14.8k you got.

I realise now that this doesn't tell the whole story (not by half!), but it was at least fun doing the maths
(Yeah, I'm a huge nerd!)

Originally Posted by bluesman7

It really won't do you any good. The material of the grit, grit size distribution, grit/binder ratio, binder material, all come into play. In the end you just have to see how a stone behaves.

No one ever made a more true statement than Glen's:

"No amount of money spent on a Stone can ever replace the value of the time it takes learning to use it properly"

Here's a really good one that I found....

https://docs.google.com/spreadsheets...R-o/edit#gid=0