You can also define the preferred layer in powerpcb.ini
From MG518767 (it loosk like this is from the old Mentor site)
Component outline is searched on layers in following order:
- layer defined in ini in 3D_Shape_Layer entry, section Graphics (only if value provided there is a valid layer number)
- layer 25 (125)
- top associated assembly layer
- top layer
- <All Layers>
- layer 20 (120)
To specify silkscreen as a 3D-Shape_Layer in ini-file
Open powerpcb.ini file and add 3D_shape_Layer under [Graphics] section.
3D_Shape_Layer = <layer_number>
Here are my notes on the subject (a summary of thread 16213 on this site):
Notes from Mentor blog (modified) about body to body clearance:
On Layer 26, build your silkscreen outline. Use 8 mils, 10 mils, whatever you like, don't worry about part size, make it pretty.
On Layer 19 ("3D Outlines") , build an actual size (maximum for all alternate parts) part outline. Use a 1 mil line width. This one is for assembly drawings, output to IDF. It must be a single closed polygon.
On Layer 20 ("Placement Courtyard"), copy the Layer 19 shape (1 mil), and if you need additional clearance around the part for pick and place or ICT considerations, add it here.
Set the Body to Body clearance rule to whatever you need, run your Verify Design with all outline layers except Layer 20 turned off. Now here's the trick: set up your Clearance Checking to check Placement Outline, not Body to Body (that's right, it doesn't really make sense).
Thanks Klaus- This looks good when I do the 3D preview. I've sent check files off to the mech designer, waiting to hear what he says.