double post. Nice calculator Mark, I remember seeing this before, the only thing I can fault it with is it makes a lot of assumptions. Also labeling motors like little drills, are you talking about Dewalts? RS-775s? RS-550s? RS-540s? RS-380s? All motors Ive seen come on small drills. The usage of volume is for weight calculation a good idea, but IMHO it would only work accurately if your building a brick. An advance calculator, but maybe not suited to this area.

I look forward to any updates you make on it though :-)