Sharpening - From Beginning to End

[Obsessed with Edges]

Good to know , when I said close to diamonds I should of worded it differently I always assumed as far as abrasives went it was diamonds plates then Sic . I didn't mean the numbers were close I was saying I had thought I had always read that diamonds were the hardest abrasive and sic was #2 If that makes sense ,I could be wrong I thought I read that though?

On the Mohs scale of hardness, SiC has often been 'ranked' 2nd in hardness to diamond. Problem is, the Mohs scale only indicates a ranking of hardness between each abrasive specifically listed. So, diamond is always a '10' and SiC might be shown as a '9.5', both numbers of which are unitless and only indicate a hierarchy of hardest to softest (usually talc), and not the real degree of difference (in measurable units) between them. Being a Mohs Scale '9.5' indicates that the '9th' ranked material was superceded at some point by something found to be harder, but still less hard than diamond. And these days, SiC would (or should) be ranked somewhat lower, as CBN (Knoop ~4500 or so) and other new materials are considerably harder than SiC, but still less hard than diamond. That's why I say the Mohs scale is very misleading, as it gives the impression that some materials are much, much harder than they really are, because '9.5' seems very, very close to '10'. Think of it as a scoreboard at a race track, which indicates who came in '1st place', and who came in 'last', without actually showing the elapsed times of each (this is called an 'ordinal' scale, only indicating an order of ranking, and no other measurable criteria, like finishing times or actual speeds). Could be 10 world-class racers with merely 10ths or 100ths of a second separating '1st' and '10th', or just 10 random participants with minutes or hours separating the best from the worst. The overall ranking would still appear the same, without indicating how fast or slow each actually was.

The Mohs Scale was originally created for 10 tiers of hardness, limiting it to only 10 listed materials. For this reason, as more and more materials beyond the original 10 are listed, the 'fractional' positions like '9.5' are arbitrarily created to fit the others somewhere into the rankings between the softest (always at '1') and the hardest (always at '10'). Those 'fractional' values, I think, help lend to the illusion of measured precision where there really isn't any.


David

 

[CoGraphic]

Did dmt get back with you fairly quickly ? I emailed them 3 weeks ago about a dmt EEF ,not wearing out but it's waay too coarse and it was some tool marks in the plate and I have to heard a thing

I had to call them back a few days later but yeah they send me the return slip i just ahve to send it out. Although they did say it'l probably take about a month to get me a new stone.

 

[Spartan00]

Month for a new stone isn't bad , especially and let's be honest lol hell I tore up one using too much pressure so I'm guilty too , especially when that's the situation . I'm not ripping on you in saying that's good by them if they replace it even if it wasn't a defect.