Quote Originally Posted by Russel Baldridge View Post
I'd be really interested to know how the two compare in the flatness aspect.

I have been wondering what all of this means anyway. I mean, since the high and low spots will be rubbed back and forth over the stone, wouldn't they be averaged out to a mostly uniform level?
Congratulations! Give the man a cigar! He figured it out!

Yes, exactly, the minor variations balance out due to the actual lapping motions.... and what little variation is left is infinitesimally insignificant when it comes to using such a surface to hone a bevel that is only 0.075" wide. And further to that, as you use an ever so slightly out of flat diamond hone, any diamonds sticking further out from the surface than the rest will take the brunt of the initial lapping until they wear down to the level of the others. Diamonds below the initial surface level won't wear at all until the other diamonds wear down to their level...

It's what makes lapping work and why a cast iron lapping plate used with loose grit in a machine shop lasts for decades if used correctly as lapping will keep it and what you are lapping flat.

Regards

Christian