I decided to scrap the idea of making my own beam and decided to use an 8"x8" beam (the real name for it is W8 x31).
I'll enclose the ends of the beam as was suggested. I only plan to use it horizontally, and will make it so I can lower it completely to the ground if I have a big round to roll onto it. I'll likely make some kind of outfeed table for it.

I'll enclose the ends of the beam as was suggested. I only plan to use it horizontally, and will make it so I can lower it completely to the ground if I have a big round to roll onto it. I'll likely make some kind of outfeed table for it.
