@thomthom said: I see this from time to time. Usually it's a result of using imported geometry from for instance DWG/DXF files with some minor precision problems that appear to cascade throughout the model. Maybe CleanUp: http://sketchucation.com/forums/viewtopic.php?t=22920 But it won't prevent the problem from re-appearing. The root cause if probably precision problems. Use imported geometry as a guide, but don't model directly off it. Don't trust it to be square or parallel. Thank you so much for the input Thomthom. This is actually quite helpful. ^.^