Why is the machined edge of my dish model rough or have a ridge around it?

Anytime you create a project with a dish or other recessed shape it is good practice to create a Zero Plane for the shape to merge with. This allows the software to better define the exact point where the recessed shape meets the surface, which will result in a better toolpath and smooth machined surface.

A ridge around the recessed shape could be caused by many reasons and they are typically associated with how the project has been designed and set up.

We cannot cover all the possibilities here, but one quick check you can make is to check is the Model Position in Material. Open the Material Setup form using the icon on the Toolpath Tab setup-material-rapid-gaps and verify the Gap Above Model is set to 0.0.

If this does not help, it is suggested you create a new post on the main forum and ask for possible ideas and solutions. Providing the file (only if it does not contain any protected 3D models or vector designs) always helps, as does pictures and screen prints. Normally, the more information you can provide the faster and better the responses will be.