[greybeard]

Let me explain myself..

.........You do have to observe Cameron's sizing formula, of course, but anything you have is a good starting point. It's all about matching components. Not about matching the right components. ........

Absolutely agree Walter, and that's the direction I'm hoping to take.
To that end I'm still going with the idea that we need to know what sizes and in what proportion we've got in our various purchases.

I did a search of the patents on particle size separation/analysis and found one based on the principle of using an air stream to do the separation.
Based on their design I've produced the following sketch, and am putting together the materials over this weekend.
I've tried to keep to the idea that it needs to be very simple to build so that anyone can copy it.
It does have various inadequacies (like me) but it should manage the separation ok.

I've found simply poking the tips of a cheap micrometer into a small heap of dried sand produces quite consistent results on measurement of particle diameter, so that's what I plan to do for measuring the sizes.
This will then give me where to place the collecting divisions (insted of the corrugated plastic in the diagram) for the second run, when I'm trying to get the recipe separation.

I hope this all makes some sort of sense. Any questions of detail please ask.

John