Hi MichaelT - if I open up the STEP file in Rhino, I get units set to cm in there.

Also if you open up the STEP file in a text editor like notepad, you can actually scroll down and see that the units seem to be set to centimeters, this is the relevant part of the file:

#99=(
LENGTH_UNIT()
NAMED_UNIT(*)
SI_UNIT(.CENTI.,.METRE.)
);

There seems to be some problem in MoI's STEP importer that is not reading in that units setting properly though. I'll explore this some and find out if this can be fixed, it may be something that needs to be fixed by the author of the import libraries that MoI uses.


> but I imported the same Alibre AP 203 Step file into
> ViacAD, TurboCAD Pro and IronCAD's Inovate and they
> all came in correct to scale in millimeters.

They seem to be converting from the centimeter units that are actually set in the file into mm.

I guess that those systems are working more like MoI's import command where the units setting retains its current setting when opening that file and instead the imported file is scaled to convert into the current unit system, rather than the current unit system actually getting set to what was in the file.


> if someone were to receive a STEP or SAT file from Alibre
> and open it in MoI without paying attention, they could be
> heading for disaster downstream.

Actually the SAT file seems to be working fine as far as units go - when you open the file up in MoI you get the units set to cm with the part in the proper size in centimeters.

I also double checked the SAT file by directly loading it into notepad as well, and in its header it is marked as having the units in the file as cm as well - the setting for that is not as easy to see as the STEP file one, it comes from the 3rd line in the file which says:

10 9.9999999999999995e-007 1e-010

The 10 there at the front of that line means that each numeric unit in the file represents 10mm , or in other words the numbers stored in the file are stored as centimeters.

- Michael