If you are importing a disk in Sum3D and you notice it is missing holes, you need to add them. To add them follow these instructions:
Bring in the disk that has the missing curves or holes.
Bring in some units. You want to get units that are pretty much the same size as the missing holes.
Turn the equipment on using
Click the top view on the quick views tool bar
Then do not zoom in or out. What this does is it puts the disk in Sum3D in the same orientation and size as the disk physically in your hand.
You can now hold the physical disk and put it right on your computer screen, and line up the line up line with the line in Sum3D.
**If you want to just mill and avoid the holes, move the units away from the holes like in the video above. If you want to save the actual curves so in the future those are now blocked out holes, place the units into the holes**