[cadandcookies]

I'm not really sure what you mean by "we couldn't get what we wanted" out of the JVN calculator. Were you using the single speed or two speed tabs? Were you using all the tooth counts of gears that are available from FIRST vendors?

My typical process for drive train gearboxes is to determine what my design parameters are for the gearbox (shifting or no? max speed/min speed? certain time to distance requirements?), then playing around with JVN until I get a set of gear ratios that work.

I guess the main thing about the JVN calulator is that, like all calculators, it's only as good as what you put into it. It's not magic-- one of the often ignored parts of design is determining what exactly you want out of what you're designing. In my experience there hasn't been a single gearbox I've designed that the design wasn't at least in part simplified by the JVN calculator.