[Wren Hensgen]

The reason the alignment doesn't work out nicely is that in reality, the sides of the bar are very slightly sloped inwards, so that they flex when you tighten down the T-nut. This creates a spring force that eliminates the need for a lock washer or lock nut.

If you're using Inventor, I'd suggest making a flat work plane across each face, and then a centerline, and constraining to those, then hiding their visibility.

Just so you know, with 80/20 profiles, the 80/20 company doesn't use 3-d cad models, preferring to use wireframes in 3-d Autocad.