Hi Tom,
I don't have Bobcad 19 to inspect, but I have had similar experiences sometimes, with some dxf files. For what it is worth, I usually make sure nothing is blanked and do a select all. This sometimes will show some kind of a weird structure off somewhere in the drawing, that, as far as I can tell, is garbage, but because it exists, this could be the reason why your real drawing is so teensy weensy: everything is in view, including the garbage. So select the garbage area with a zoom select and delete it or blank it, then try a view all again.
Chances are, your part will be okay, without resizing.
Oh, check your units of export, and make sure it matches up with your Bobcad environment units. Perhaps this might throw things off scale.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)