Bad Objects are those that violate NURBS (Non-Uniform Rational B-Splines) rules or have structural problems - they often appear after joining and Boolean operations.
The most common reason models become unprintable is due to bad objects and naked edges. Pro-Tip: Check out our guide on How to Conduct a Tolerance Analysis for 3D Printed Parts if you have complex tolerance requirements and want a simple way to perform a tolerance analysis.
No matter what units you use to create your model, files exported from Rhino are almost always read as mm, so set your units to mm before exporting your file for printing. Rhino file tolerance can be set from the document properties window in the units tab. A good rule of thumb is to set your Rhino tolerance to be 10 times that of the printer tolerance (i.e printer tolerance is 0.1mm, so Rhino tolerance should be set to 0.01mm).
You first need to set correct tolerances before you start modeling by finding the tolerance of the program you are exporting your model to.
