Jason,
The ballast from the IKEA screen looks like it's the finest, is it too fine? The other 2 piles look almost the same.
Dave
It's possible that it's too fine but then so might be the AZ Rock because 98% (visual test) passed through the screen too.
I took some sample measurements and here's what I got (in N scale).
2.4", 2.24", 2.56", 2.56", 1.84", 2.4"
It would seem that I could be missing some 3"-3.2" inch pieces that would be nice but I have to be aware that when I measure, the little piece of walnut might be flipping to it's skinniest cross-section each time when I squeeze it in the calipers. If nothing else, I can probably assume that I'll never measure a piece at it's widest point unless I go under the optivisor and try and guess when I first touch the edges.
As for the other two piles, there is a difference. A larger sample would show that or maybe I should have just had a pile of the stuff that didn't pass the faucet screen and you'd see the difference for sure.
Jason