Hi Burr, thanks for posting the sample files. I tried importing them in a couple of other programs too, like Alibre, Rhino, and ViaCAD, and all give the same results with seeing the file's units as being in mm.

So as best I can tell, that's just something that BobCAD decides to do, it seems to decide to only want to write IGES and STEP files with millimeter units instead of what your current BobCAD units are. Maybe there is an option in there somewhere to tell it to stop doing that and use your current units instead of only mm?

Anyway, it's not actually particularly harmful because like you said it actually preserves the proper size of your object. It wrote out your box with 2 inch sides as a box with 50.8 mm sides, and 2 inches does equal 50.8 mm, so the actual size is still maintained.

> (In moi, the object is actually changed/scaled)

Yeah, there is a setting for this so you can decide if you want objects scaled numerically when units change or not so as to maintain the same physically measured size. That's under Options > General > "Unit options" button.



Another way you can do things if you like is to use File > Import to bring the file in, rather than using File > Open.

When you "Open" a file, it means that you are also bringing in some settings from that file like the unit system that it was using.

But when you "Import" a file, it will keep your current settings (and other geometry as well) intact and if the imported file is in different units it will scale it into the current unit system (unless you turn off the option for doing that, it's also under Options > General > "Unit options" button).

So for example if you start up MoI, then set your units to Inches, then do a File > Import of one of your example files there, you will then end up with a 2 inch cube and won't need to alter any units setting since the imported geometry will adapt to your current unit setting rather than the setting being changed.

- Michael