Export Step Model - Preferred Settings

AD19 OutJob

AD19 File Export Options

Output Job Options to Export a Step Model in AD14

Options for (save as) Export a Step Model in AD14

That's it !

Mounting Holes - Generating 3D CAD File - YouTube

Altium Designer - Generating 3D CAD File - You Tube

Are your mounting holes shown in your Altium 3D Step Model?

Robert Feranec has a work around to fix missing mounting holes in the Altium 3D Step Models.

1. Place Circle on any Layer
2. Set Radius for Hole Size
3. Tools > Convert  > Create Board Cut Out From Selected Primitives
4. Delete the Circle
5. Ignore DRC Errors for the Board Cut Outs 

Altium sort'a fixed this problem in one of the releases of AD13. 

Options have been added to Export the Mechanical Mounting Holes in the Outjob Configuration.

Note that the above screen shot is from the output job in AD(13.3).

As shown below the options for Exporting the Step file are different if you export the step model from the file menu selection 'Save Copy As'.

Why are there two different option dialogs for exporting the step models ?

The output job step model export method includes the mounting holes when selected as shown above in the first screen shot.

I reported this as bug #2890 back in May of 2013, the bug has 4 votes, so it will not likely get fixed. If you want it fixed cast your vote at bug  #2890