This is critical. You need to tell Mastercam the size of the raw bar stock. Use the "Make from 2 points" or "Cylinder" options. Don't forget to add a little extra on the face for a facing cut and enough "meat" in the back for the chuck jaws to grab! 3. The Facing Operation Always start by cleaning up the face of the part. Select Lathe Face .
Since you are inside SOLIDWORKS, you can use the Manager Tree to select the edges of your model. Mastercam 2017 is great at "seeing" the profile of your solid. Mastercam 2017 for SOLIDWORKS Tutorial (Lathe)
Before you click a single toolpath button, make sure your environment is set up: This is critical