Received a stp. file from "manufacturing engineers" and cannot perform feature recognition (fails due to invalid geometry). I have decided to re-engineer this part using the stp. file as a reference. Digging deeper into the stp. file it is apparent that there is not any true geometry associated with it (everything is a spline). Now I am stuck in my sld.prt file because I cannot shell the part. The ribs (created using Sweeps) have tangency issues between faces (not sure why the path used is the same as the cut-section profile sketch used in the revolve feature to create the main body) . I have tried to replace the sweep feature with the loft feature for the ribs and still have the same tangency issue. Any help would be appreciated!