I finally figured out a cheap and easy (kind of) way to make supported linear rails. 3/8" x 1" and 3/8" x 1.75" solid bar forms a "T" onto which the 3/4" ss shaft rests. I was a bit shocked at the $50 price tag for the two 12' lengths of aluminum bar, but it is enough to make two sets of x-axis ways and is very rigid when bolted to the shaft.
I broke several 10-24 taps while trying to tap the holes in the 3/4" ss shaft. That stuff is super hard and very difficult to work with. I think 3/4" CRS would work just as well and be easier to work with. Note: Drywall screw and leaf shown for size comparison.
This 6' piece will be cut in half to form the 34" ways that I need for the IG-88.
I'm so amazed at how well this worked out. The HBLB's are incredible!