Lecture Autodesk inventor: Multiview projections 3. The main contents of the chapter consist of the following: Third-angle projection, first-angle projection, third and first-angle projection, view selection, line precedence, intersections and tangency, | Multiview Projections 3 Third-Angle Projection Used in the United States to determine arrangement of multiviews Views projected onto projection plane in front of object First-Angle Projection Used in Europe and Asia to determine arrangement of multiviews Views projected onto projection plane behind object Third and First-Angle Projection I II III IV View Selection Most descriptive view selected as the front view Longest dimension should appear in front view as a horizontal dimension Use minimum number of views that completely describe object Choose views to minimize number of hidden lines Line Precedence Visible Hidden Center When lines coincide with each other, more important lines take precedence over other lines. The order of precedence is: Intersections and Tangency Planar surface tangent to contoured surface no line drawn Planar surface intersects a contoured surface line (edge) drawn Show edge No edge Fillets and Rounds Fillet – inside rounding on a cast, forged or plastic part Round – outside rounding on a cast, forged or plastic part Typically 3 - 5 mm radius In multiview drawings, fillets/rounds only represented in views where you see curved shape Fillets and Rounds - Conventions No true change in planes when surfaces are related by a fillet/round Multiview convention - add lines as if fillets/rounds were absent Revolution Conventions True multiview projections can be confusing when showing radially distributed features By convention, these views are typically simplified by rotating the radial features along horizontal and vertical centerlines Machined Holes Through Hole A hole that goes all the way through the object Blind Hole A hole that does not pass all the way through the object Counterbore Hole Used to allow bolt heads to be flush with or below the surface Spotface Hole Provides smooth surface for fastener heads to rest on a cast part Countersink Hole Used for flat-head fasteners Multiview Projections - | Multiview Projections 3 Third-Angle Projection Used in the United States to determine arrangement of multiviews Views projected onto projection plane in front of object First-Angle Projection Used in Europe and Asia to determine arrangement of multiviews Views projected onto projection plane behind object Third and First-Angle Projection I II III IV View Selection Most descriptive view selected as the front view Longest dimension should appear in front view as a horizontal dimension Use minimum number of views that completely describe object Choose views to minimize number of hidden lines Line Precedence Visible Hidden Center When lines coincide with each other, more important lines take precedence over other lines. The order of precedence is: Intersections and Tangency Planar surface tangent to contoured surface no line drawn Planar surface intersects a contoured surface line (edge) drawn Show edge No edge Fillets and Rounds Fillet – inside rounding on a cast, forged or plastic .
