Thread: Grit diameter vs grit number vs scale

Originally Posted by time2shave

I have read suggestions to go from 8k Norton to 8k Naniwa to 12k Naniwa.

May be you can post the context of these suggestions? Original links are great.

I read in another forum

http://badgerandblade.com/vb/showthread.php?t=195635

Sounds like you are going largely on the posts of one particular member in that thread. I'm by no means saying he is right or wrong - I don't know because I have not tried using the hones in question together in a progression. I also don't know anything about his honing experience.

I would suggest sticking to advice in posts by people known by reputation, such as the SRP Mentors and/or Mods, or other senior members here with known honing skills.

As far as going from the Norton 8k to the Naniwa 12k, I would assume it would work just fine. There are, however, some hones from different manufacturers that are said to "not play nicely together." Again, not something I have personally experienced (but there are many hones I have not used and many things I have not yet experienced).

I just wish there was a good way to cross-reference different scales without any confusion.

I don't know about grit microns and whatnot, but I can tell you for certain that going from a Norton 8k to a Naniwa 12k works just fine.
I do it all the time.

Originally Posted by time2shave

I just wish there was a good way to cross-reference different scales without any confusion.

The confusion only comes into it if you expect specific outcomes based solely on given grit ratings. If you can lay aside the expectation that two different hones can be easily compared by grit rating alone then I think that will alleviate some of the grit rating scale confusion for you

As far as trying to help answer your first question, this article might widen your horizons a little on that specific subject of grit rating relating to grit particle size Formulae For Converting Between Grit and Microns - Straight Razor Place Wiki

Originally Posted by time2shave

I read in another forum

http://badgerandblade.com/vb/showthread.php?t=195635

Yes, this puts things in context. There is only one person with very limited experience honing, and just as limited variation of hones, who is saying that he does this and it works well for him. In another month or three he may have very different way of doing things too.

Then there's somebody else just making something up because they couldn't find the answer for it.

I don't see how that relates to any comparison of fineness or grits of these hones.

I think it's best if you take a step back and reevaluate everything that has been said on the subject, i.e. even if you can compare grit numbers directly you still will know nothing relevant about how the hones will compare when sharpening razors.

So, I took data from:
Conversion Chart Abrasives - Grit Sizes
I plotted the relationship between the ANSI grit number and micron size in Excel.
My results differ from what I found in:
Formulae For Converting Between Grit and Microns - Straight Razor Place Wiki
(Or is it for the Japanese scale? I can't tell.)

I got for ANSI:
Grit = 4999 * Microns ^ (-0.789)
Microns = 46042 * Grit ^ (-1.257)

I really think you are WAY too worried about grit size. As Hoglagoo said above, the grit size is NOT a full picture of how a hone will cut steel.

Originally Posted by time2shave

So, I took data from:
Conversion Chart Abrasives - Grit Sizes

....

My results differ from what I found in:
Formulae For Converting Between Grit and Microns - Straight Razor Place Wiki

This is because the underlying data is different. From your source ANSI 1200 corresponds to 5u, on the sources from the wiki 1200 corresponds to 15u. Same thing with the rest.

You should figure out how to reconcile the original data before moving to further manipulation.