ATM Got my BVC blank

["bprewitt" <bprewitt@neo.rr.com>]

My 20" f5 BVC blank arrived yesterday.

They did a nice job of generating the f5 curve, and it has a smooth bevel.
It's a bit over 2" thick, and weighs 58 pounds.
It looks like Obsidian.

The back of the blank isn't ground, so I'll start by grinding it flat on
plate glass.
I'll post my experience with this material as I go.

Can anybody suggest any useful measurements that could be made with simple
tools ?
I'd like to be able to measure the coefficient of thermal expansion.
I was thinking of comparing marks on the blank against a plate glass
reference at different temperatures.
I have an Edmund measuring reticle good to .001 inch, and a 14" long plate
glass (Xerox) flat.

       Bill Prewitt

My webpage of CCD imaging, Telescope making, and Caving:
http://home.neo.rr.com/imaging