>guess another test you could do would be to start a new file in MoI, set units to mm, then create a sphere of radius 127 mm - then import this into BobCAD - does this then show a value of exactly 5 inches in Bobcad?>

This is exactly the case Michael.

If you could respond one last time with what I could approach the BobCad people with, that would help to set me in the right direction.

Thanks again for the support,
Burr