For some reason in 2.4 when I put a subdivision on an object the edges get this kind of dashed looked ad start to run alone the edge when the object moves. It reminds me of when you had your normals reversed in previous blender builds. Here’s a pic to show what I mean, is there anyone who knows what causes this.
did you use bevel on these mechanical parts?
did you use SubSurf and set some Creases values?
Do you use the default Lambert diffuse shader, or the Toon shader? Did you activate Edge rendering Scene/Render buttons/Output pannel?
Did you use full OSA, or any filter for antialiasing?
Could you supply a blend file with the problem?
Have you tried control-n to recalc normals?
I put a subdivision modifier with some crease values on the edges I want.
then re-apply ‘Set smooth’ AFTER creases
perhaps the changed geometry is not, in you case, smoothed by default if the primal mesh is smoothed