Introduction to 3D Modeling PDF

Introduction to 3D Modeling  Technical Graphics  Visual communications language of the engineer and technologist.  Incorporates text, images, and numeric information.  Includes everything from traditional types of engineering drawings to sophisticated computer models. A graphical...

Introduction to 3D Modeling  Technical Graphics  Visual communications language of the engineer and technologist.  Incorporates text, images, and numeric information.  Includes everything from traditional types of engineering drawings to sophisticated computer models. A graphical representation can be done using:  Freehand  Mechanical Drawing  Computer methods  Provides graphics with sufficient clarity such that others are able to visualize the design. https://www.3dhubs.com/knowledge-base/how-prepare-technical-drawing-cnc-m achining The Importance of Technical Graphics Technical graphics is a real and complete language used in the design process for:  Visualization  Communication  Documentation  Initial Drawings to Visualize Concepts  Leonardo da Vinci used drawing as a means of visualizing his design  Early sketches didn’t have dimensions or any specifications.  Drawings were accompanied by a short description of the object and its functionality. The Atomic Crossbow of Leonardo da Vinci  Documentation  Graphics is the most effective way to permanently record the design solution.  Before 3-D modeling, Documentation drawings were 2-D detail drawings that were copied through a process called blueprinting used to produce the design.  3-D models can be used directly by machines (3D printers, CNC Machines) to create the design.  Documentation drawings follow very strict standard practices so everyone in the engineering field can “read” the drawings.  These standards are the “language” used to communicate graphically.  Communication Provide sufficient graphics clarity that others are able to visualize the design.  Engineers  Technicians  Manufacturing personnel  Marketing Personnel  etc.  What is hand drafting ?  Creating shapes of 3D objects on 2D paper with geometric precision is hand drafting.  How to show 3D object on paper?  Hand Drafting Necessity  Engineering objects are precise in shape and need precise drawings  Describing these complicated engineering objects verbally or in written paragraphs is extremely difficult and not accurate  One picture is worth a thousand words – Albert Einstein  Example of Drafting/ 2D Drawing Multiview drawing of a part https://static.sdcpublications.com/multimedia/9781630570521-sample/ege/ortho/ ortho_page1.htm  Orthographic Views Engineering way of looking at object Consider an object confined in a glass box and each face is considered individually  If three faces are considered, we get “three different views of the same object” These views are “Orthographic Views” Orthographic Views-Examples  3D Models  Created by Computer Aided Design (CAD) software tools.stl File CAM 3D Printer  Input to Computer Aided Manufacturing CAD Model Software xxx (CAM) tools CAM CNC  Output from CAM Software yyy Machine  Computer Numerical Control (CNC) machines(subtractive Engineering.pdf File Universally Viewable manufacturing) Drawings Drawings  Three Dimensional (3D) Printers (additive manufacturing) NX Computer  Visual Science  Defined as the study of the processes that produce images in the mind. It has at least three major categories:  Spatial cognition: The ability to think quickly and recognize complex mental models, i.e., the mental process used to perceive, store, recall, create, edit, and communicate spatial images.  Imaging: The process of producing and reproducing ideas and creating graphics.  Geometry: The branch of mathematics that deals with properties, relationships and measurements of points, lines, planes and solids.  Geometry-1  The foundation for technical graphics.  It includes:  Plane geometry: planar figures, such as circles and triangles, and their relationships  Solid geometry: 3D objects, such as cylinders, cones, and cubes, and their relationships.  Geometry-2  Analytic geometry: The analysis of geometric structures and properties, using algebraic operations and position coordinates.  Descriptive geometry: The analysis of space distances and relationships, using graphics.  Conventions  Are commonly accepted practices, rules, or methods.  Examples: In a technical drawing  dashed lines on multi-view drawings are used to designate a feature hidden from the current viewpoint.  the combination of a long line-short line- long line represents the center of an object  Standards  Are sets of rules that govern how technical drawings are represented in order to allow clear communication of technical ideas.  These standards comprise the “language” used to communicate graphically. Example:  Mechanical drawings are dimensioned using an accepted set of standards, such as placing the dimension type at the bottom of the sheet  Diametric dimensions should be preceded by a Φ symbol. Examp le:  Orthographic  Views Three mostly used view are:  Front View  Top View  Side View (Right)  Mirror Views of these 3 create another 3 views:  Rear View  Bottom View  Side View (Left)  Isometric View Isometric view shows object at an angle Gives depth perception Most pictures of objects we see in any literature are isometric for representative purposes The isometric view helps in understanding orthographic views Our brains are accustomed to see isometric views Example https://www.hubs.com/knowledge-base/how-prepare-tec hnical-drawing-cnc-machining/  Necessity of CAD Software  Hand drawn graphics are time consuming.  It requires patience and skills which take years to master. Drawing a 3D representation ( isometric view ) is difficult. Parametric modeling is not possible with hand drafting. Difficult to store hand drawn CAD sheets. Converting hand drawn object to any manufacturing code directly is almost impossible.  Common Symbols Counters Counterb ink Angle Counters ore ink Φ Diameter Symbol Diameter Diameter ⌴ Counterbore Symbol Depth ⌵ Countersink Symbol ↧ Depth Symbol ∠ Angle Symbol × Number of repeated Thru- Thru- features (e.g. holes) Hole Dia. Hole Dia. R Radius symbol Countersink Counterbore The larger hole is drilled at ° Degree Symbol The larger hole is drilled an angle, ideally to match ⌒ Arc Symbol straight into the material at a the tapered angle of the shallower depth than the fastener smaller inner shaft.  References Bertoline, G., Wiebe, E., Hartman, N. and Ross, W., Technical Graphics Communication, 4th edition, Irwin Graphics Series, 1997, ISBN-10: 0256229813. This is one of the best CAD books for beginners.