Our problem is that line weights in elevation drawings, where we set Detail Level to Medium, are slightly inconsistent.
Apparently, what happens is that because all beam edges (and for that matter other steel framing element edges) are displayed, the beam flanges are effectively drawn with a double line. If the flange is thinner, the lines overlap more and this results in lighter line weight. If the flange is thicker, the lines overlap less and this results in heavier line weight.
Is there a way to fix it?
I see two ways to avoid this problem, but, as far as I can tell, both are not possible:
Revit could be smart enough to merge two partially overlapping lines depending on the view scale and the line thickness.
Inner flange edges could be hidden. (And I do not mean using Linework tool, because it would take forever to do it manually.)
Unfortunately it is not possible to tell Revit not to display one of the lines when they are close together. You would likely see better results with Thin Lines turned on, but that would affect all lines in the view.
If you edit the family, in a plan view you'll see the lines used for this representation, and that they are assigned to the Hidden Faces subcategory. You could create a new Subcategory - ie Hidden Faces 2 - and assign one of the two lines to it. Then inside the project you could go into V/G and turn off that second line... But that would affect anything on Hidden Faces 2 - which would include the larger sizes that show okay (assuming it's all the same family). They'd have to be split into separate families to avoid that, so that there is no Hidden Faces 2 assigned to anything in the larger sizes.
Not sure if the above is worth it, but I figured I would mention it.
Katie Langan Technical Support Specialist Customer Service & Support Autodesk, Inc.
I don't think the Thin Lines tool helps here, because it applies only to zooming in views and not to printing.
I'm also afraid your workaround does not work, because the hidden lines that you're talking about are where the flange meets the web, but there are still two edges at the flange tips. Those edges cannot be moved to a separate subcategory, because they are a part of the sweep.
Anyway, it looks like it's not possible to fix it. I'll report it as a feature request.