Stereolithography specialist 3D Systems offers monthly tips on its website (www.3dsystems.com). A recent "Tech Tip" discussed building stereolithography parts with geometries that have near flat surfaces or surface angle changes as a function of Z height. Following is the company's advice:

"On certain extreme geometries, you may note artifacts (bumps or ridges) on the part if it is prepared and built using the default value of .004 inch in 'minimum width for small fills (3D Lightyear)' or 'minimum width for fills (Maestro).' Instead, set the variable to zero or to .001 inch, and the artifacts will disappear. Also note that inclined styles are available for many of the machine/resin combinations. Using those styles can have a dramatic effect on low sloping, downfacing surfaces."

3D Systems
www.3dsystems.com