Brent:
Thanks! Your posts never fail to challenge & inform!

On 11/21/2012 10:49 AM, Brent Beach wrote:
> On diamond stones to flatten other abrasive stones
>
> On 2012-11-20 20:21, Joshua Clark wrote:
>> I keep my waterstones flat with a 220 grit DMT stone, a good

>
> The larger the included angle the greater the stress (force) when the 
> grit particle abrades the metal surface. The greater the stress the 
> greater the resulting dislocation of the crystal matrix. The weaker 
> the metal. The faster your tool will dull.
>
I don't understand that. I would have thought that particles with larger 
included angles would exert lower pressure (assuming a constant force 
over a larger area), and sharpen less effectively.
Please elaborate.

> Diamond is unusual in this regard. Most other ways of flattening will 
> dislodge grits, not fracture them, because the second surface is not 
> so much harder than the stone you are flattening. In the case of 
> flattening on cement, the second surface is softer and will almost 
> always dislodge grits rather than fracture them.
>
> Waterstones have a soft binder - grits are more likely to dislodge 
> rather than fracture. The harder the binder the more likely you are to 
> get fracturing.
>

So diamond stones might be good for conditioning some waterstones, but 
will actually damage hard oilstones and other stones with a harder matrix?

Don
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