Creating 3D Primitives and Composites in AutoCAD

Transcription

1 Professor John R. Bordeau Kankakee Community College AC4815 This class will introduce creating primitive and composite solid models in AutoCAD. Attendees will create a 3D model by creating a solid primitive, such as a box, cone, or cylinder. More advanced models, called composites, will be molded by using the Union and Subtract commands. Models are shaped by cutting holes, rounding edges, and adding materials until the final shape and form of the object is made. Learning Objectives At the end of this class, you will be able to: Construct 3D solid primitives Explain the dynamic feedback presented when constructing solid primitives Create complex solids using the Union command Remove portions of a solid using the Subtract command About the Speaker John is a professor at Kankakee Community College. He has 15 years of CAD teaching experience at universities and colleges. His professional experience covers the span of 30 years, including 13 years of expertise in managing all aspects of the CAD function for large organizations with multiple engineering disciplines, and remote offices such as AECOM and STS Consultants. John s four main areas of specialization include CAD management and education, information technology, training and performance improvement, and industrial technology. His education includes an MS in training and organizational development from Northern Michigan University. The research project for his master's degree was "AutoCAD E- Learning Objects for the Adult Learner." Additionally, he has a BS in industrial technology and applied sciences with a minor in CAD. jbordeau@kcc.edu

2 Getting Ready to Design in 3D Selecting a Drawing Template File A set of drawing template files is installed with AutoCAD. Many of them are provided either for imperial or for metric units, and some are optimized for 3D modeling. All drawing template files have a.dwt file extension. You should use the acad3d.dwt or acadiso3d.dwt for 3D design. While these drawing templates provide a quick way to start a new drawing, it is best to create drawing templates specific to your company and the type of drawings you create. To start a drawing by selecting a template file 1. Click the Application menu, and click New menu Drawing. 2. In the Select Template dialog box, select a template from the list. 3. Click Open. Selecting a Workspace Workspaces are sets of menus, toolbars, palettes, and ribbon control panels that are grouped and organized so that you can work in a custom, task-oriented drawing environment. When you use a workspace, only the menus, toolbars, and palettes that are relevant to a task are displayed. In addition, a workspace may automatically display the ribbon, a special palette with task-specific control panels. You can easily switch between workspaces. The following task-based workspaces are already defined in the product: 2D Drafting & Annotation 3D Basic 3D Modeling AutoCAD Classic For example, when you create 3D models, you can use the 3D Basics or 3D Modeling workspace that contains only 3D-related toolbars, menus, and palettes. Interface items that you do not need for 3D modeling are hidden, maximizing the screen area available for your work. We will use the 3D Basics Workspace for this virtual class. To switch workspaces 1. On the status bar, click Workspace Switching. 2. From the list of workspaces, select the workspace you want to switch to. The workspace with a check mark is your current workspace. 2

3 Using a Visual Style to Display Your Model Visual styles control the display of edges and shading a viewport. Control the effect of a visual style by changing its properties. When you apply a visual style or change its settings, the associated viewport is automatically updated to reflect those changes. The Visual Styles Manager displays all visual styles available in the drawing. The selected visual style is indicated by a yellow border, and its settings are displayed in the panel below the sample images. From the ribbon, you can change some frequently used settings or open the Visual Styles Manager. The following predefined visual styles are supplied with the product: 2D Wireframe. Displays objects using lines and curves to represent the boundaries. NoteRaster images, OLE objects, linetypes, and lineweights are visible. Conceptual. Displays objects using smooth shading and the Gooch face style. The Gooch face style transitions between cool and warm colors, rather than dark and light. The effect is less realistic, but it can make the details of the model easier to see. Hidden. Displays objects using wireframe representation and hides lines representing back faces. Realistic. Displays objects using smooth shading and materials. Shaded. Displays objects using smooth shading. Shaded with Edges. Displays objects using smooth shading and visible edges. Shades of Gray. Displays objects using smooth shading and monochromatic shades of gray. Sketchy. Displays objects with a hand-sketched effect by using the Line Extensions and Jitter edge modifiers. Wireframe. Displays objects using lines and curves to represent the boundaries. X-ray. Displays objects with partial transparency. To apply a visual style to a viewport 1. Click View tab Visual Styles panel Visual Styles Manager. 2. Click in the viewport to make it current. 3. In the Visual Styles Manager, double-click the sample image of the visual style. The selected visual style is applied to the model in the viewport. An icon in the sample image indicates that the visual style is in use in the current viewport. When you change viewports, the icon changes to indicate that the visual style is in use in the current drawing. Using a View Cube to View your Model ViewCube tool is a navigation tool that is displayed when you are working in 2D model space or 3D visual style. With ViewCube tool, you can switch between standard and isometric views. The ViewCube tool is a persistent, clickable and draggable interface that you use to switch between standard and isometric views of your model. When you display the ViewCube tool, it is shown in one of the corners of the window over the model in an inactive state. The ViewCube tool provides visual feedback about the current viewpoint of the model as view changes occur. When the cursor is positioned over the ViewCube tool, it becomes active. You can drag or click the ViewCube, switch to one of the available preset views, roll the current view, or change to the Home view of the model. 3

4 Reorient the Current View You can reorient the current view of a model by clicking predefined areas on the ViewCube tool or dragging the ViewCube tool. The ViewCube tool provides twenty-six defined parts to click and change the current view of a model. The twenty-six defined parts are categorized into three groups: corner, edge, and face. Of the twenty-six defined parts, six of the parts represent standard orthogonal views of a model: top, bottom, front, back, left, and right. Orthogonal views are set by clicking one of the faces on the ViewCube tool. You use the other twenty defined parts to access angled views of a model. Clicking one of the corners on the ViewCube tool reorients the current view of the model to a three-quarter view, based on a viewpoint defined by three sides of the model. Clicking one of the edges reorients the view of the model to a half view based on two sides of the model. Using Dynamic Input and Feedback Dynamic Input provides a command interface near the cursor to help you keep your focus in the drafting area. When dynamic input is on, tooltips display information near the cursor that is dynamically updated as the cursor moves. When a command is active, the tooltips provide a place for user entry. After you type a value in an input field and press Tab, the field then displays a lock icon, and the cursor is constrained by the value that you entered. You can then enter a value for the second input field. Alternately, if you type a value and press Enter, the second input field is ignored and the value is interpreted as direct distance entry. The actions required to complete a command or to use grips are similar to those for the Command prompt. The difference is that your attention can stay near the cursor. Dynamic input is not designed to replace the command line. You can hide the command line to add screen area for drawing, but you will need to display it for some operations. To enter coordinate values in dynamic input tooltips 1. On the status bar, verify that the dynamic input button is on. 2. Use one of the following methods to enter coordinate values or select options: To enter polar coordinates, enter the distance from the first point and press Tab, and then enter an angle value and press Enter. To enter Cartesian coordinates, enter an X coordinate value and a comma (,), and then enter a Y coordinate value and press Enter. If a down-arrow icon follows the prompt, press the DOWN ARROW key until a dot is displayed next to the option. Press Enter. Press the UP ARROW key to access recent coordinates, or right-click and click Recent Input to access the coordinates from a shortcut menu. 4

5 To set options for Dynamic Input: Z Field 1. Click the Application button. At the bottom of the Application menu, click Options. 2. In the Options dialog box, click the 3D Modeling tab. 3. Set options as desired. Dynamic Input Controls the display of dynamic input fields for coordinate entry. Show Z Field for Pointer Input Displays a field for the Z coordinate when using dynamic input. 4. Do either or both of the following: Click Apply to record the current options settings in the system registry. Click OK to record the current options settings in the system registry and close the Options dialog box. Constructing 3D Solid Primitives Box Primitive Box Creation Options Use the following options to control the size and rotation of the boxes you create: Create a cube. Use the Cube option of the BOX command to create a box with sides of equal length. Specify rotation. Use the Cube or Length option if you want to set the rotation of the box in the XY plane. Start from the center point. Use the Center Point option to create a box using a specified center point. To create a solid box based on two points and a height 1. Click Home tab Modeling panel Box. 2. Specify the first corner of the base. 3. Specify the opposite corner of the base. 4. Specify the height. To create a solid cube 1. Click Home tab Modeling panel Box. 2. Specify the first corner, or enter c (Center) to specify the center point of the base. 3. At the Command prompt, enter c (Cube). Specify the length of the cube and a rotation angle. The length value sets both the width and height of the cube. 5

6 Cylinder Primitive Cylinder Creation Options Use the following options to control the size and rotation of the cylinders you create: Set rotation. Use the Axis Endpoint option of the CYLINDER command to set the height and rotation of the cylinder. The center point of the top plane of the cylinder is the axis endpoint, which can be located anywhere in 3D space. Use three points to define the base. Use the 3P (Three Points) option to define the base of the cylinder. You can set three points anywhere in 3D space. Construct a cylindrical form with special detail, such as grooves. Create a closed polyline (PLINE to represent a 2D profile of the base. Use EXTRUDE to define the height along the Z axis. The resulting extruded solid is not a true solid cylinder primitive. To create a solid cylinder with a circular base 1. Click Home tab Modeling panel Cylinder. 2. Specify the center point of the base. 3. Specify the radius or diameter of the base. 4. Specify the height of the cylinder. To create a solid cylinder with an elliptical base 1. Click Home tab Modeling panel Cylinder. 2. At the Command prompt, enter e (Elliptical). 3. Specify the start point of the first axis. 4. Specify the endpoint of the first axis. 5. Specify the endpoint (length and rotation) of the second axis. 6. Specify the height of the cylinder. Cone Primitive Cone Creation Options Use the following options to control the size and rotation of cones you create: Set the height and orientation. Use the Axis Endpoint option of the CONE command. Use the Top Radius option to specify the axis endpoint as the point of the cone or the center of the top face. The axis endpoint can be located anywhere in 3D space. Create a frustum of a cone. Use the Top Radius option of the CONE command to create a frustum, which tapers to an elliptical or planar face. The Frustum tool is also available from the Modeling tab of the tool palette. You can also use grips to modify the tip of a cone and convert it to a flat face. Specify circumference and base plane. The 3P (Three Points) option of the CONE command defines the size and plane of the base of the cone anywhere in 3D space. Define the angle of the taper. To create a conical solid that requires a specific angle to define its sides, draw a 2D circle. Then use EXTRUDE and the Taper Angle option to taper the circle at an angle along the Z axis. This method, however, creates an extruded solid, not a true solid cone primitive. 6

7 To create a solid cone with a circular base 1. Click Home tab Modeling panel Cone. 2. Specify the center point of the base. 3. Specify the radius or diameter of the base. 4. Specify the height of the cone. To create a solid cone with an elliptical base 1. Click Home tab Modeling panel Cone. 2. At the Command prompt, enter e (Elliptical). 3. Specify the start point of first axis. 4. Specify the endpoint of the first axis. 5. Specify the endpoint (length and rotation) of the second axis. 6. Specify the height of the cone. To create a frustum of a solid cone 1. Click Home tab Modeling panel Cone. 2. Specify the center point of the base. 3. Specify the radius or diameter of the base. 4. At the Command prompt, enter t (Top radius). Specify the top radius. 5. Specify the height of the cone. Sphere Primitive Sphere Creation Options Use the following options to draw a sphere with the SPHERE command: Specify three points to set the size and plane of the circumference or radius. Use the 3P (Three Points) option to define the size of the sphere anywhere in 3D space. The three points also define the plane of the circumference. Specify two points to set the circumference or radius. Use the 2P (Two Points) option to define the size of the sphere anywhere in 3D space. The plane of the circumference matches the Z value of the first point. Set the size and location of the sphere based on other objects. Use the Ttr (Tangent, Tangent, Radius) option to define a sphere that is tangent to two circles, arcs, lines, and some 3D objects. The tangency points are projected onto the current UCS. To create a solid sphere 1. Click Home tab Modeling panel Sphere. 2. Specify the center of the sphere. 3. Specify the radius or diameter of the sphere 7

8 Pyramid Primitive Pyramid Creation Options Use the following options to control the size, shape, and rotation of the pyramids you create: Set the number of sides. Use the Sides option of the PYRAMID command to set the number of sides for the pyramid. Set the length of the edges. Use the Edges option to specify the dimension of the sides at the base. Create a frustum of a pyramid. Use the Top Radius option to create a frustum, which tapers to a planar face. The frustum face is parallel to, and has the same number of sides as, the base. To create a solid pyramid 1. Click Home tab Modeling panel Pyramid. 2. At the Command prompt, enter s (Sides). Enter the number of sides to use. 3. Specify the center point of the base. 4. Specify the radius or diameter of the base. 5. Specify the height of the pyramid. To create a frustum of a solid pyramid 1. Click Home tab Modeling panel Pyramid. 2. At the Command prompt, enter s (Sides). Enter the number of sides to use. 3. Specify the center point of the base. 4. Specify the radius or diameter of the base. 5. Enter t (Top radius). Specify the radius of the planar face at the top of the pyramid. 6. Specify the height of the pyramid. Wedge Primitive Wedge Creation Options Use the following options to control the size and rotation of the wedges you create: Create a wedge with sides of equal length. Use the Cube option of the WEDGE command. Specify rotation. Use the Cube or Length option if you want to set the rotation of the wedge in the XY plane. Start from the center point. Use the Center Point option to create a wedge using a specified center point. To create a solid wedge based on two points and a height 1. Click Home tab Modeling panel Wedge. 2. Specify the first corner of the base. 3. Specify the opposite corner of the base. 4. Specify the height of the wedge To create a solid wedge with equal length, width, and height 1. Click Home tab Modeling panel Wedge. 2. Specify the first corner or enter c (Center) to set the center point of the base. 8

9 3. At the Command prompt, enter c (Cube). Specify the length of the wedge and a rotation angle. The length value sets both the width and height of the wedge. Torus Primitive Torus Creation Options Use the following options to control the size and rotation of the tori you create. Set the size and plane of the circumference or radius. Use the 3P (Three Points) option to define the size of the torus anywhere in 3D space. The three points also define the plane of the circumference. Use this option to rotate the torus as you create it. Set the circumference or radius. Use the 2P (Two Points) option to define the size of the torus anywhere in 3D space. The plane of the circumference matches the Z value of the first point. Set the size and location of the torus based on other objects. Use the Ttr (Tangent, Tangent, Radius) option to define a torus that is tangent to two circles, arcs, lines, and some 3D objects. The tangency points are projected onto the current UCS. To create a solid torus 1. Click Home tab Modeling panel Torus. 2. Specify the center of the torus. 3. Specify the radius or diameter of the path that is swept by the torus tube. 4. Specify the radius or diameter of the tube. Polysolid Primitive Polysolid Creation Options Use the following options to control the size and shape of the polysolids you create: Create arced segments. Use the Arc option to add curved segments to the polysolid. The profile of a polysolid with curved segments remains perpendicular to the path. Create a polysolid from a 2D object. Use the Object option to convert an object such as a polyline, circle, line, or arc to a polysolid. The DELOBJ system variable controls whether the path (a 2D object) is automatically deleted when you create a polysolid. Close the gap between the first and last points. Use the Close option to create a connecting segment. Set the height and width. Use the Height and Width options for the POLYSOLID command. The values you set are stored in the PSOLWIDTH and PSOLHEIGHT system variables. Set where the object is drawn in relation to the specified points. Use the Justification option to place the path of the polysolid to the right, to the left, or down the center of the points you specify. To draw a polysolid 1. Click Home tab Modeling panel Polysolid. 2. Specify a start point. 3. Specify the next point. 9

10 To create a curved segment, at the Command prompt, enter a (Arc) and specify the next point. 4. Repeat step 3 to complete the desired solid. 5. Press Enter. Creating Composite Objects Create composite 3D objects by combining, subtracting, or finding the intersecting mass of two or more 3D solids, surfaces, or regions. Composite solids are created from two or more solids, surfaces, or regions through any of the following commands: UNION, SUBTRACT, and INTERSECT. Methods for Creating Composite Objects Three methods are available for creating composite solids, surfaces, or regions: Combine two or more objects. With UNION, you can combine the total volume of two or more objects. Subtract one set of solids from another. With SUBTRACT, you can remove the common area of one set of solids from another. For example, you can use SUBTRACT to add holes to a mechanical part by subtracting cylinders from the object. Find the common volume. With INTERSECT, you can create a composite solid from the common volume of two or more overlapping solids. INTERSECT removes the portions that do not overlap and creates a composite solid from the common volume. To combine two or more objects 1. Click Home tab Solid Editing panel Union. 2. Select the 3D solid, surface, or region objects to combine. Press Enter. To subtract objects from one another 1. Click Home tab Solid Editing panel Subtract. 2. Select the 3D solid, surface, or region to subtract from. Press Enter. 3. Select the 3D solid, surface, or region to subtract. Press Enter. To create a compound object from the intersection with other objects 1. Click Home tab Solid Editing panel Intersect. 2. Select the 3D solid, surface, or region to intersect. Press Enter. 10

11 Checking Interference Methods for Checking Interference You can check interference using the following methods: Define one selection set. Check the interference of all the 3D solids and surfaces in a single selection set. Define two selection sets. Check the interference of the objects in the first set of objects against the objects in the second selection set. Individually specify solids that are nested within blocks or xrefs. Individually select 3D solid or surface objects that are nested in blocks and external references (xrefs) and compare them against other objects in the selection set. To check for interferences within a solid model 1. Click Home tab Solid Editing panel Interference Checking. 2. Select the first set of 3D solids and surfaces in the model. Press Enter. 3. Select the second set of 3D solids and surfaces in the model. Press Enter. The Interference Checking dialog box is displayed. The areas of interference are displayed as new, highlighted solid objects. 4. To cycle through the interference objects, in the Interference Checking dialog box, click Next and Previous. 5. To retain the new interference objects after you close the Interference Checking dialog box, clear Delete Interference Objects Created on Close. 6. Click Close. If Delete Interference Objects on Close is selected, the new interference objects are deleted. 11