Chris, in that sample you show there the bit would almost never be "normal" to the face of the part, so even on a 3 axis machine you'd still, for lack of a better word get that "tilt" that you want.

That Harvey tool article makes sense if you're something like metal where you can't sand it afterwards. In my view doing a contoured surface like that doesn't justify multi axis unless there are parts you literally cannot reach with a 3 axis machine.

That all being said, you are limited on the shapes that you can make with a 3 axis machine. 5 axis opens up a whole new level of creativity.

Perhaps you could get one of these:

https://www.amazon.com/Router-Machin...605561&sr=8-14

Bolt it to your table, and run the axis from your ShopBot control. Depending on the vintage of your control board you may have the IO to run something like this.