I'm one of those lucky guys with a small machine shop. I shopped around for equipment and figured out it would be cheaper and more fun to fabricate my own equipment. What I can't seem to find is an actual formula to figure a pre-boil volume for a given post boil volume. I know that the diameter of the BK factors in as well as the boil time. Anyone have info or thoughts on this? I'm not going to buy software to make beer and I doubt Beersmith gets this in depth anyway.