How do CAD designers account for the fact that a blank may have to be flipped to a different side in order to allow the piece to be completely milled through a CNC system?
It appears that three planes need to be surfaced in order to mill the object.
- The bottom plane of the block has a slight concave shape
- The side plane has two hollowed out shapes that would not be accessible from either the top or bottom planes
- The top plane has a slightly concave inflection applied to the slope
And there are several cuts that go all the way through the blank.
It seems easy enough to mill the bottom shape first, including any through cuts from the bottom. This work on the bottom wouldn't significantly affect the overall shape of the blank, and there shouldn't be any complications moving to the next plane.
But after you complete the bottom, milling either the side or the top would appear to create problems for flipping the blank to the final plane. Specifically, the outline of the original blank would have changed significantly enough that prior mill registrations would be thrown off.
I suspect that this is a somewhat common problem as complex shapes are fairly commonplace. And I'm more interested in the general approach to solving this problem than I am about how the example car would be designed.
So how does a CAD designer account for the fact that the edges of the blank will be changing during milling and that those changes may (will) complicate the milling process?
Disclaimer: My knowledge of CAD design and CNC manufacturing is fairly limited. My knowledge comes primarily from what I picked up at University and has been supplemented by advanced DIY projects.