One very frustrating situation for a woodworker is having an otherwise nice board which has acquired a bit of a twist along it’s length. Feeding it through a planer won’t get it out. Even if you have a jointer wide enough, it still takes quite a bit of skill and time to remove the twist.
The CNC router makes short work of it. I enhanced this image a bit to make it easier to see the gap under the closest corner of the board. This was before the board was surfaced, the thickness is pretty uniform.
Here is a picture of the other end after surfacing. The top surface is now flat, the difference in thickness from left to right shows how twisted it was. I then flipped it over and cut it to uniform thickness. If you had a pile of twisted boards to flatten out, you might just flatten one side on the CNC router, and then feed them through a planer. Actually any piece of wood that would fit on the four foot square table and under the 6 inch gantry could be easily made flat as a pool table. This could include a big slab of a tree or a butcher block.
And last (but not least) is the cutter which makes it possible. The carbide tips (inserts) which do the actual cutting are only about 2 bucks each and have 4 usable cutting edges.