Ok, here is a basic conceptual picture. Say your stock blank is a 2x6 of some length (wood colored part). You would add an extra few inches in length at each end (the white ends) that remain attached until you are done machining all four sides, then when you are all done you cut those off. The CAD program lets you create tabs that go between the sacrificial ends and the actual workpiece and won’t cutt them out. Then you can rotate the workpiece in your fixture (the blue part that is clamped down to your CNC table top).
This particular one I drew would be for when you are machining from the surface of the blank because it will keep the surface of all 4 sides at the same exact Z height as you rotate it.
You could also change it up a little so that it keeps the center axis of the workpiece at the same Z height (like a rotary units used as an indexer would do). In that case, your modeling is referencing the center axis instead of the surface.
Does that make sense?
