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Parametric Technology Corporation Feature-based Modeling User Guide and Menu Reference CADDS® 5i Release 12 DOC38305-008 Copyright © 2001 Parametric Technology Corporation. All Rights Reserved. User documentation from Parametric Technology Corporation (PTC) is subject to copyright laws of the United States and other countries and is provided under a license agreement, which restricts copying, disclosure, and use of such documentation. PTC hereby grants to the licensed user the right to make copies in printed form of PTC user documentation provided on software or documentation media, but only for internal, noncommercial use by the licensed user in accordance with the license agreement under which the applicable software and documentation are licensed. Any copy made hereunder shall include the Parametric Technology Corporation copyright notice and any other proprietary notice provided by PTC. 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Parametric Technology Corporation, 140 Kendrick Street, Needham, MA 02494-2714 8 January 2001 Feature-based Modeling User Guide and Menu Reference Contents-v Table of Contents Preface Related Documents ________________________________________ xiii Book Conventions __________________________________________ xiv Window Managers and the User Interface ___________________ xv Online User Documentation _________________________________ xv Online Command Help _____________________________________ xvi Printing Documentation ____________________________________ xvi Resources and Services ____________________________________ xvii Documentation Comments ________________________________ xvii Introduction to Feature-based Modeling Overview of Feature-based Modeling ____________________________ 1-2 Why use Feature-based Modeling? _________________________ 1-2 Object-oriented Methodology _____________________________ 1-2 Concepts and Definitions ________________________________________ 1-3 Feature Instances and Workpieces _________________________ 1-3 Sample Session: Inserting an Instance of a Boss ______________ 1-3 Attributes _________________________________________________ 1-4 Definitions and Inheritance_________________________________ 1-4 Representations and Teach Feature Sessions ________________ 1-4 Attribute Association_______________________________________ 1-4 Libraries of Features _______________________________________ 1-5 System Features and User-defined Features _________________ 1-5 Browsing through Lists ______________________________________ 1-5 Contents-vi Feature-based Modeling User Guide and Menu Reference Inserting an Instance Overview of Inserting Instances ___________________________________ 2-2 Inserting Feature ______________________________________________ 2-4 Viewing a Feature Before Inserting It____________________________ 2-4 Displaying a Feature While Inserting It __________________________ 2-6 Inserting a Feature Using the Normal Option _________________ 2-7 Rotating an Inserted Feature ________________________________ 2-7 Removing an Instance_________________________________________ 2-8 Description of Options ______________________________________ 2-8 Representation Command Files ________________________________ 2-9 What You Must Specify ________________________________________ 2-9 Attributes of Size____________________________________________ 2-9 Application ______________________________________________ 2-10 Methods of Applying an Instance to a Workpiece________________ 2-12 Exit and Entry Faces _________________________________________ 2-12 Example _________________________________________________ 2-12 Extend ______________________________________________________ 2-13 Example _________________________________________________ 2-13 Merge ______________________________________________________ 2-13 Boolean ____________________________________________________ 2-14 Extended Boolean___________________________________________ 2-14 Example _________________________________________________ 2-14 Considerations Regarding Booleans and Local Operations ____________________________________________ 2-15 NoApply ____________________________________________________ 2-15 System Features ________________________________________________ 2-16 SYSLIB____________________________________________________ 2-16 The Virtual Library ________________________________________ 2-16 Same Feature Name Exists Across Libraries _________________ 2-17 Library Options ___________________________________________ 2-18 Setting the Tolerance Value for System Library Features _______ 2-19 Categories of System Features __________________________________ 2-21 Additive Features ___________________________________________ 2-21 Example _________________________________________________ 2-21 Subtractive Features_________________________________________ 2-22 Feature-based Modeling User Guide and Menu Reference Contents-vii Example _________________________________________________ 2-22 Thru Holes and Cutouts ___________________________________ 2-23 Flats and Grooves ________________________________________ 2-24 Full and Partial Slots_______________________________________ 2-26 System Feature Options from the Features Task Set ____________ 2-28 Description of Options _______________________________________ 2-29 Sample Session: Inserting an Instance ___________________________ 2-38 Instance Information Retrieval: The Verify Feature Option_________ 2-43 When Instance is Active _____________________________________ 2-43 Entering Conditional Expressions___________________________ 2-44 When Class is Active_________________________________________ 2-46 Instance Modification: The Change Feature Option ______________ 2-47 Selecting an Instance_____________________________________ 2-47 Choosing and Modifying Attributes ________________________ 2-49 Creating a Feature Overview of User-defined Features _______________________________ 3-2 Modifying a Definition ________________________________________ 3-2 Modifying a Representation___________________________________ 3-3 Creating a Definition ____________________________________________ 3-4 Overview of the Process ______________________________________ 3-4 Entering Attributes _________________________________________ 3-4 Options Related to Creating a Definition_______________________ 3-5 Description of Options _____________________________________ 3-5 You Can Create a Definition in the LDM ____________________ 3-8 Library Options in the LDM _________________________________ 3-9 Multiple Inheritance __________________________________________ 3-9 Basic Concept ____________________________________________ 3-9 Conflicts across Superclasses ______________________________ 3-10 Utilizing Inheritance _______________________________________ 3-11 The System Superclass Feature _______________________________ 3-11 What is the Class Feature? ________________________________ 3-11 Changing the Default ____________________________________ 3-11 If Feature is not an Appropriate Superclass_________________ 3-11 The System Superclass Primitive_______________________________ 3-12 Contents-viii Feature-based Modeling User Guide and Menu Reference Creating a Representation _____________________________________ 3-13 Overview of the Process __________________________________ 3-13 Associating Attributes to a Representation _________________ 3-13 User Dimensions and Constraints __________________________ 3-14 Features Having Parametrically Controlled Groups of Entities _________________________________________ 3-14 Exiting a Teach Feature Session and Locking _______________ 3-15 Options Related to Creating a Representation ________________ 3-16 Teach Feature Options within the LDM_____________________ 3-16 Teach Feature ___________________________________________ 3-16 Options within a Teach Feature Session ____________________ 3-18 Delete Feature ___________________________________________ 3-18 Sample Session: Creating a Feature _____________________________ 3-19 The Definition _______________________________________________ 3-19 The Representation__________________________________________ 3-21 The Rotational Sweep ____________________________________ 3-21 The User Dimensions ______________________________________ 3-23 Association of the Attributes ______________________________ 3-24 The Constraints ___________________________________________ 3-25 Model Regeneration _____________________________________ 3-26 Orientation and Origin____________________________________ 3-26 Using Properties Concepts________________________________________________________ 4-2 What Are Properties? _______________________________________ 4-2 Why Use Properties? ________________________________________ 4-2 How Do You Use Properties? ________________________________ 4-2 Creating a Property ______________________________________________ 4-3 Modifying a Class __________________________________________ 4-3 Property Attributes__________________________________________ 4-3 Inheritance ________________________________________________ 4-4 Property Libraries ___________________________________________ 4-4 The Define Property Property Sheet __________________________ 4-5 Sample Session _____________________________________________ 4-6 Deleting a Property ____________________________________________ 4-12 Example _________________________________________________ 4-12 Feature-based Modeling User Guide and Menu Reference Contents-ix What If Instances Exist? ___________________________________ 4-12 What About Superclass? __________________________________ 4-13 Sample Session ___________________________________________ 4-13 Inserting a Property_____________________________________________ 4-14 Attaching a Property Instance ____________________________ 4-14 You Cannot See a Property Instance ______________________ 4-15 Assigning Attribute Values_________________________________ 4-15 Tagnames________________________________________________ 4-15 The Insert Property Property Sheet _________________________ 4-16 Sample Session ___________________________________________ 4-17 Selecting a Property Instance ___________________________________ 4-19 Options Requiring Instance Selection ______________________ 4-19 Property Instance Selection Options _______________________ 4-20 More on Selecting by Condition ___________________________ 4-20 Changing Property Attribute Values _____________________________ 4-22 Select Instance by Tagname ______________________________ 4-22 The Change Property Property Sheet ______________________ 4-22 Sample Session ___________________________________________ 4-23 Removing a Property Instance __________________________________ 4-25 The Remove Property Property Sheet ______________________ 4-25 Sample Session ___________________________________________ 4-26 Making Attachments ___________________________________________ 4-27 Multiple Instances and Attachments_______________________ 4-27 If You Change an Attached Instance______________________ 4-27 The Attach Property Property Sheet________________________ 4-28 Sample Session ___________________________________________ 4-29 If You Delete An Attached Entity __________________________ 4-33 Detaching a Property Instance__________________________________ 4-34 If You Detach All Attachments ____________________________ 4-35 Multiple Detachments ____________________________________ 4-35 The Detach Property Property Sheet _______________________ 4-35 Sample Session ___________________________________________ 4-37 Verifying a Property ____________________________________________ 4-42 The Verify Property Property Sheet _________________________ 4-42 Sample Session ___________________________________________ 4-43 Contents-x Feature-based Modeling User Guide and Menu Reference Taxonomy of System Features Overview _______________________________________________________ A-2 Advantages of Classifying Features_________________________ A-2 System Features ___________________________________________ A-2 Form Features Information Model ________________________________ A-3 Form Features ________________________________________________ A-3 Volume Features _____________________________________________ A-3 Additive Features__________________________________________ A-3 Subtractive Features_______________________________________ A-4 System Features _________________________________________________ A-5 Tabs ______________________________________________________ A-5 Bosses ____________________________________________________ A-5 Circular Bosses ____________________________________________ A-5 Counterbores _____________________________________________ A-5 Countersinks ______________________________________________ A-5 Pockets ___________________________________________________ A-5 Grooves __________________________________________________ A-6 Flats ______________________________________________________ A-6 Slots ______________________________________________________ A-6 Cutouts ___________________________________________________ A-6 Diagrams of Form Features and System Features __________________ A-7 Form Features Diagrams ___________________________________ A-7 System Features Diagrams _________________________________ A-7 Command File for Hole_ConicalBottom Inserting the Rotational Sweep ______________________________ B-2 Inserting the User Dimensions ________________________________ B-2 Associating the Attributes ___________________________________ B-2 Setting Constraints__________________________________________ B-2 Defining an Orientation _____________________________________ B-3 Exiting the Part _____________________________________________ B-3 Troubleshooting Messages within an Application Session __________________________ C-2 Feature-based Modeling User Guide and Menu Reference Contents-xi Messages for Modeling with Features _____________________________ C-3 Messages for Defining Features __________________________________ C-4 Messages for Teach Feature Definitions ___________________________ C-6 Setup Procedures Installing and Setting Up the Features Database __________________ D-2 The Features Database _______________________________________ D-2 Features Process___________________________________________ D-2 Features Libraries _____________________________________________ D-2 Creating a Local Features Database Manually ________________ D-4 Installing the Local Features Database______________________ D-4 Testing the Features Database Setup _______________________ D-6 Creating a Shared Features Database ________________________ D-6 Advantages of a Shared Database_________________________ D-6 Set up the Client Systems __________________________________ D-7 Test the Features Database Setup _________________________ D-9 Features Libraries on Client Systems ___________________________ D-9 Example of Cross Mounting _______________________________ D-10 Starting the Features Process ________________________________ D-10 If the Process Does Not Start _________________________________ D-11 Releasing the Port ________________________________________ D-12 Choosing a New Port _____________________________________ D-12 SunOS and HP ____________________________________________ D-12 Solaris____________________________________________________ D-12 Accessing a Local Features Database___________________________ D-13 Switching Features Databases __________________________________ D-14 Copying a Features Library ____________________________________ D-15 Copying a Features Library to Another Library_________________ D-15 Copying a Features Library from LDM _________________________ D-16 Copying a Features Library To Tarfile or Tape__________________ D-16 Copying a Features Library from Tarfile or Tape _______________ D-17 Backing Up Features Libraries ___________________________________ D-18 Updating the LDM with a New Revision _________________________ D-19 Feature-based Modeling User Guide and Menu Reference xiii Preface Feature-based Modeling User Guide and Menu Reference assumes that you are familiar with parametric modeling functionality as described in the Parametric User Guide and Menu Reference. This document describes how to perform the following tasks: • Basic concepts and terminology of feature-based modeling • How to insert a feature • How to create a feature • Feature-related menus • Feature-based properties Related Documents The following documents may be helpful as you use Feature-based Modeling User Guide and Menu Reference: • Introduction to CADDS 5i • Installing CADDS 5i • Managing CADDS 5i • Parametric Modeling User Guide and Menu Reference • Customizer and Icon Editor User Guide Preface xiv Feature-based Modeling User Guide and Menu Reference Book Conventions The following table illustrates and explains conventions used in writing about CADDS applications. Convention Example Explanation Menu selections and options List Section option, Specify Layer field Indicates a selection you must make from a menu or property sheet or a text field that you must fill in. User-selected graphic location X, d1 or P1 Marks a location or entity selection in graphic examples. User input in CADDS text fields and on any command line cvaec.hd.data.param tar -xvf /dev/rst0 Enter the text in a CADDS text field or on any command line. System output Binary transfer complete. Indicates system responses in the CADDS text window or on any command line. Variable in user input tar -cvf /dev/rst0 filename Replace the variable with an appropriate substitute; for example, replace filename with an actual file name. Variable in text tagname Indicates a variable that requires an appropriate substitute when used in a real operation; for example, replace tagname with an actual tag name. CADDS commands and modifiers INSERT LINE TANTO Shows CADDS commands and modifiers as they appear in the command line interface. Text string "SRFGROUPA" or ’SRFGROUPA’ Shows text strings. You must enclose text string with single or double quotation marks. Integer n Supply an integer for the n. Real number x Supply a real number for the x. # # mkdir /cdrom Indicates the root (superuser) prompt on command lines. % % rlogin remote_system_name -l root Indicates the C shell prompt on command lines. $ $ rlogin remote_system_name -l root Indicates the Bourne shell prompt on command lines. Preface Feature-based Modeling User Guide and Menu Reference xv Window Managers and the User Interface According to the window manager that you use, the look and feel of the user interface in CADDS can change. Refer to the following table: Online User Documentation Online documentation for each book is provided in HTML if the documentation CD-ROM is installed. You can view the online documentation in the following ways: • From an HTML browser • From the Information Access button on the CADDS desktop or the Local Data Manager (LDM) Please note: The LDM is valid only for standalone CADDS. You can also view the online documentation directly from the CD-ROM without installing it. From an HTML Browser: 1. Navigate to the directory where the documents are installed. For example, /usr/apl/cadds/data/html/htmldoc/ (UNIX) Drive:\usr\apl\cadds\data\html\htmldoc\ (Windows NT) 2. Click mainmenu.html. A list of available CADDS documentation appears. 3. Click the book title you want to view. From the Information Access Button on the CADDS Desktop or LDM: 1. Start CADDS. 2. Choose Information Access, the i button, in the top-left corner of the CADDS desktop or the LDM. 3. Choose DOCUMENTATION. A list of available CADDS documentation appears. 4. Click the book title you want to view. Look and Feel of User Interface Elements User Interface Element Common Desktop Environment (CDE) on Solaris, HP, DEC, and IBM Window Manager Other Than CDE on Solaris, HP, DEC, IBM, SGI, and NT Option button ON — Round, filled in the center OFF — Round, empty ON — Diamond, filled OFF — Diamond, empty Toggle key ON — Square with a check mark OFF — Square, empty ON — Square, filled OFF — Square, empty Preface xvi Feature-based Modeling User Guide and Menu Reference From the Documentation CD-ROM: 1. Mount the documentation CD-ROM. 2. Point your browser to: CDROM_mount_point/htmldoc/mainmenu.html (UNIX) CDROM_Drive:\htmldoc\mainmenu.html (Windows NT) Online Command Help You can view the online command help directly from the CADDS desktop in the following ways: • From the Information Access button on the CADDS desktop or the LDM • From the command line From the Information Access Button on the CADDS Desktop or LDM: 1. Start CADDS. 2. Choose Information Access, the i button, in the top-left corner of the CADDS desktop or the LDM. 3. Choose COMMAND HELP. The Command Help property sheet opens displaying a list of verb-noun combinations of commands. From the Command Line: Type the exclamation mark (!) to display online documentation before typing the verb-noun combination as follows: #01#!INSERT LINE Printing Documentation A PDF (Portable Document Format) file is included on the CD-ROM for each online book. See the first page of each online book for the document number referenced in the PDF file name. Check with your system administrator if you need more information. You must have Acrobat Reader installed to view and print PDF files. The default documentation directories are: • /usr/apl/cadds/data/html/pdf/doc_number.pdf (UNIX) • CDROM_Drive:\usr\apl\cadds\data\html\pdf\doc_number.pdf (Windows NT) Preface Feature-based Modeling User Guide and Menu Reference xvii Resources and Services For resources and services to help you with PTC (Parametric Technology Corporation) software products, see the PTC Customer Service Guide. It includes instructions for using the World Wide Web or fax transmissions for customer support. Documentation Comments PTC welcomes your suggestions and comments. You can send feedback in the following ways: • Send comments electronically to firstname.lastname@example.org. • Fill out and mail the PTC Documentation Survey located in the PTC Customer Service Guide. Feature-based Modeling User Guide and Menu Reference 1-1 Chapter 1 Introduction to Feature-based Modeling This chapter introduces you to the basic concepts and terminology of feature-based modeling. • Overview of Feature-based Modeling • Concepts and Definitions Introduction to Feature-based Modeling Overview of Feature-based Modeling 1-2 Feature-based Modeling User Guide and Menu Reference Overview of Feature-based Modeling Essentially, feature-based modeling in the Parametric environment of CADDS involves inserting intelligent geometry into a model. Why use Feature-based Modeling? Using feature-based modeling includes a number of advantages. You can: • Insert intelligent parametric geometry into a model without having to visualize, then create, the intermediate construction geometry. • Associate a variety of information to portions of a model. • Create a set of features with attributes unique to your design requirements. Object-oriented Methodology Feature-based modeling uses object-oriented methodology. While knowledge of object-oriented design (OOD) concepts is helpful, it is not required to use feature-based modeling. Introduction to Feature-based Modeling Concepts and Definitions Feature-based Modeling User Guide and Menu Reference 1-3 Concepts and Definitions The following sections describes the concepts of feature-based modeling. Feature Instances and Workpieces Feature-based modeling allows you to insert features (such as a hole, a boss, or a slot) into a model. Each occurrence of a feature in a model is called an instance. The object within a model, into which, an instance is inserted is called a workpiece. Sample Session: Inserting an Instance of a Boss Consider the following example. Your current part contains a solid to which you want to add a boss. Using feature-based modeling, you can proceed as follows: 1. Select the feature called Boss_Circular. 2. Assign values to its attributes, that is, topdiameter, bossheight, draft angle. 3. Insert one or more instances. 4. Parametrically change the attribute values of an instance(s). 5. Obtain a report (verify) on an instance. The following illustration shows an instance of the feature Boss_Circular inserted into a workpiece. Introduction to Feature-based Modeling Concepts and Definitions 1-4 Feature-based Modeling User Guide and Menu Reference Attributes An attribute is a characteristic of a feature. Attributes are either static or dynamic. The value of a static attribute is assigned during the definition of the feature. You cannot change that value when you insert an instance. Static attributes are often referred to as class attributes. You can change the default value of a dynamic attribute when inserting an instance of that feature. Dynamic attributes are often referred to as instance attributes. An attribute can describe either geometric or nongeometric data. For example, one attribute can specify a hole’s diameter and another can specify with what material the hole is to be plated. In such a case the diameter attribute describes geometric data and the plating material attribute describes nongeometric data. Definitions and Inheritance A definition is a set of attributes that characterizes a particular feature. These attributes are associated to the parameters of a geometric representation. For example, the definition for a hole feature can contain the attributes radius and depth. A definition does not contain any parametric history or geometry. Subclasses and Superclasses: A definition can inherit attributes from other definitions. Definitions utilizing inheritance are categorized as either subclasses or superclasses. A superclass is a definition whose attributes are referenced by another definition called a subclass. Multiple Inheritance: One superclass may have multiple subclasses and one subclass may have multiple superclasses. The latter concept is called multiple inheritance. For more information on multiple inheritance see “Multiple Inheritance” on page 3-9. Representations and Teach Feature Sessions A representation is essentially a model containing the parametric history captured during a special session called a Teach Feature session, or Teach session. In this session you create the geometry for the feature. The resulting parametric history is captured and stored in the representation. Attribute Association During a Teach Feature session you associate the attributes of a definition to the representation of that definition. You do so by using the Associate Attribute option which allows you to select a particular option and associate it to a particular parametric dimension, label, user-dimension, or geometric entity by means of a graphical selection. Introduction to Feature-based Modeling Concepts and Definitions Feature-based Modeling User Guide and Menu Reference 1-5 Libraries of Features A library contains a collection of features. The following illustration shows: • A library of features • A given feature within that library • The contents of the individual feature • The contents of each file type within a given individual feature library as indicated by the dotted lines System Features and User-defined Features A library called SYSLIB contains a set of system features. The taxonomy of these system features is based on the Product Data Exchange Standard (PDES), which is outlined in Appendix A, “Taxonomy of System Features.” You can select and insert one of these system features. You can also define your own feature. Doing so involves a multistep process that is described in Chapter 3, “Creating a Feature.” Browsing through Lists Browsing functionality allows you to browse through lists of libraries, features, and attributes. Menus provide lists for a set of items from which you can make a selection. Feature-based Modeling User Guide and Menu Reference 2-1 Chapter 2 Inserting an Instance This chapter explains how to insert an instance of a feature. • Overview of Inserting Instances • Methods of Applying an Instance to a Workpiece • System Features • Categories of System Features • Sample Session: Inserting an Instance • Instance Information Retrieval: The Verify Feature Option • Instance Modification: The Change Feature Option Inserting an Instance Overview of Inserting Instances 2-2 Feature-based Modeling User Guide and Menu Reference Overview of Inserting Instances Select the area shown in the following illustration to display the task set from which you can access the Features menu. Inserting an Instance Overview of Inserting Instances Feature-based Modeling User Guide and Menu Reference 2-3 Figure 2-1 The Features Task Set Inserting an Instance Overview of Inserting Instances 2-4 Feature-based Modeling User Guide and Menu Reference Inserting Feature Choose the Insert Feature icon on the task set, to get the Insert Feature property sheet, which appears as shown in the following illustration. The Feature field accesses a list of user-defined feature definitions. The set of fields (Name, Type, Value) for each attribute allows you to enter a new value for each attribute. View Feature Mode allows you to view a feature before actually inserting it. It uses the default attribute values of the feature when creating a feature view. Note that the Insert Feature property sheet allows you to select within only SYSLIB and the current user library. Use the Select Library option from the Features Task Set to change the current user library. Figure 2-2 Insert Feature Property Sheet Please note: To insert a user-defined feature, choose the Insert Feature option and specify a name. Viewing a Feature Before Inserting It If you want to view a feature before inserting it, you can do so by selecting View Feature Mode from either the Insert Feature property sheet or the Browse property sheet. The Browse property sheet allows you to browse SYSLIB and any user library. Inserting an Instance Overview of Inserting Instances Feature-based Modeling User Guide and Menu Reference 2-5 Figure 2-3 Browse Property Sheet View Feature Mode displays a graphical representation of the feature in the display area that you define by locating two points. The following illustration shows a View Feature Mode display of the system feature Cutout_Rectangular. The two location(X) marks represent the two points that define the size and shape of the display area. Figure 2-4 View Feature Mode of Cutout_Rectangular Feature Inserting an Instance Overview of Inserting Instances 2-6 Feature-based Modeling User Guide and Menu Reference You can: • Use Utilities menu options, accessed by pressing the right mouse button, or View Dynamics menu options, accessed by pressing the middle mouse button, to manipulate the graphical representation • Locate the view of a feature across multiple views • Select multiple features for viewing. The current feature display is replaced with each successive selection • Change the size or shape of the display area by selecting two corner points Choose Apply on the Insert Feature property sheet. The Insert Feature pulldown menu appears as shown below. Figure 2-5 Insert Feature pulldown menu Displaying a Feature While Inserting It While you insert a feature, you can use the Display option on the above menu to view that feature. The Display option differs from View Feature Mode in a way that, Display allows you to view a feature using the attribute values you have specified. Note that the Display option is also included on each system feature property sheet. The following illustration demonstrates how the Display option can be used to provide a display of a feature relative to the workpiece. The view shows the system feature Boss_Circular given a specified orientation and origin. Inserting an Instance Overview of Inserting Instances Feature-based Modeling User Guide and Menu Reference 2-7 Figure 2-6 Using Display option to view the feature relative to workpiece By specifying new attribute values and choosing the Display option again, you can get an updated view of the feature. Inserting a Feature Using the Normal Option The Normal option on the Insert Feature pulldown menu allows you to insert a feature or multiple copies of the feature using a built-in CPL (construction plane), which has: • ORIGIN of the given location projected normally to the entry face • Z-axis oriented normally to the outside of the entry face • X-axis oriented along the u derivative of the entry face • Y-axis oriented with respect to the X and Z axes At the end of this process, the built-in CPLs are deleted. You first need to select the entry face and the location(s) for this option. Rotating an Inserted Feature The Rotate option on the Insert Feature pulldown menu allows you to rotate the feature by 90 degrees about the Z axis while inserting it. Choose this option as many times as you want the feature to rotate by 90 degrees. You need to choose the Normal option before this option. Inserting an Instance Overview of Inserting Instances 2-8 Feature-based Modeling User Guide and Menu Reference Removing an Instance Inserting an instance is an event captured by the parametric history of the current part. Thus you can undo (remove from the parametric history) an instance insertion using the Undo operation. You can delete an unapplied instance (a feature that has been inserted using the NoApply option) or the entire workpiece using the Delete Entity option. You can also use the Remove Operation option from the Parametric menu from the top bar to remove a specified number of events. Figure 2-7 Options used to remove an Feature Instance Description of Options • Undo Operation Choose the Undo icon from the Environmental Globals area. The Undo Operation property sheet appears. Specify the index number of parametric operations you want undone. (Inserting an instance is a parametric operation.) For Example, if you enter 3, the system removes the last three operations from the parametric history. • Remove Operation Inserting an Instance Overview of Inserting Instances Feature-based Modeling User Guide and Menu Reference 2-9 Choose the Remove Operation option from the Parameter menu of the top bar. Specify the event from the parametric history you want to remove. You can: • Remove the last event • Remove the last specified number of events • Choose a specific event from the displayed list of parametric events • Delete Entity Deletes the geometry modified by an instance. That is, it deletes the workpiece. The Delete Entity option also deletes an instance that was not applied (the NoApply option). Representation Command Files If, before inserting an instance, you want to know how that feature was taught, review its representation command file. That command file is in the directory: cadds/data/features/cmd/ All command files have a .cmd suffix and contain all the commands used to create the representation. What You Must Specify An instance is an occurrence of a feature in a model. When you insert an instance, you must assign values to that feature’s attributes. When inserting a feature, you must specify a value for some or all of the following attributes: Attributes of Size Specify a real number value. Examples of such attributes are the radius of a hole, the height of a boss, and the tapered angle of a cutout. You can accept the default values or enter new values using the calculator that appears when you choose a particular attribute of size. Inserting an Instance Overview of Inserting Instances 2-10 Feature-based Modeling User Guide and Menu Reference Example: The following illustration shows the attributes of size of the system feature Boss_Circular. When you insert Boss_Circular you can change the default values of the attributes TopDiameter, BossHeight, and DraftAngle. You can do so by choosing an attribute and using the calculator that appears to enter a new value. Application Specify an operation type or application, with which the system applies an instance to the workpiece. You can choose among four applications: Extend, Extended Boolean, Boolean, and Merge. Each feature has a default application. You can alternately choose NoApply. In the case of NoApply the feature is inserted without conducting an operation. First choose an application, then specify these items: • Workpiece The object within a model into which the feature is to be inserted. For example, if you want to insert a hole feature into a block, that block is the workpiece. Select the workpiece graphically. You must select a workpiece for the Boolean and Extended Boolean applications. • Face attributes The face entities within the workpiece into which the instance is to be inserted. You must choose the face attributes for Extend, Merge, and Extended Boolean applications. Inserting an Instance Overview of Inserting Instances Feature-based Modeling User Guide and Menu Reference 2-11 • Orientation Orients the instance relative to the Cplane you select. The default orientation is relative to the active Cplane. • Origin A point in a model where an instance is inserted by its origin. For a system feature, the instance origin is indicated graphically in its respective property sheet. The default origin is the [0,0,0] of the selected orientation. You can optionally specify multiple locations and hence multiple instances. Inserting an Instance Methods of Applying an Instance to a Workpiece 2-12 Feature-based Modeling User Guide and Menu Reference Methods of Applying an Instance to a Workpiece You can choose from the following options when specifying an application: • Merge • Extend • Boolean • Extended Boolean • NoApply Please note: Merge and Extend are local operations. For more information on local operations and Booleans see the Parametric Modeling User Guide and Menu Reference. Exit and Entry Faces When specifying an application you should understand the terms entry face and exit face. Example Consider the system feature Hole_Through whose definition includes the attributes EntryFace and ExitFace. The representation of Hole_Through is a cylinder. As is shown by the following illustration, the attribute EntryFace is associated to a particular face of the Hole_Through’s representation as is its ExitFace. Inserting an Instance Methods of Applying an Instance to a Workpiece Feature-based Modeling User Guide and Menu Reference 2-13 Extend An Extend application is a local operation that translates and contours a face of the instance to a face of the workpiece. Extend is particularly useful for a workpiece that has a nonplanar face. The result of an Extend operation is two objects, because no merging of extended faces takes place. The workpiece and the feature instance remain separate objects. When you insert an instance of Hole_Through you must select an entry face and an exit face on the workpiece. The system can then extend the entry face of the representation to the entry face of the workpiece and the exit face of the representation to the exit face of the workpiece. The selection of the entry face and exit face makes selecting a workpiece unnecessary. Example The following illustration shows the result of a Thru Hole feature inserted into a model having a nonplanar face. Merge Merge is a local operation that extends a face of the instance to a face of the workpiece and merges the two by editing the face topology. The result of a Merge operation is one object. The attributes EntryFace and ExitFace function for a Merge much as they do for an Extend. Inserting an Instance Methods of Applying an Instance to a Workpiece 2-14 Feature-based Modeling User Guide and Menu Reference Boolean A Boolean constructs a single object from two or more operands. An operand is an object involved in a Boolean union, subtraction, or intersection. When you insert an instance of a feature using a Boolean application, the system treats that instance itself as the second operand. The workpiece you select becomes the first operand. The particular Boolean operation (union, subtraction, or intersection) is specified within the definition of the feature. You do not have to specify it during insertion. For example, the system feature Boss_Circular is set to a Boolean union. Extended Boolean An Extended Boolean operation combines an Extend and a Boolean operation. An Extended Boolean is particularly useful for contouring the face of an instance with a nonplanar or tapered face of a workpiece that also has intervening faces. The Extend operation is performed first, then a Boolean operation to determine a solution for the intervening faces. As is the case with a simple Boolean operation, you must select a workpiece to indicate the other operand in the operation. For an Extended Boolean you must also select an entry and exit face. Example The following illustration shows a case appropriate for an Extended Boolean operation, in that the workpiece has a tapered face and intervening faces. Inserting an Instance Methods of Applying an Instance to a Workpiece Feature-based Modeling User Guide and Menu Reference 2-15 Considerations Regarding Booleans and Local Operations You must consider the trade-off between speed and all-inclusiveness when deciding whether to specify a Boolean, or a Merge, or an Extend option. That trade-off is as follows: • Boolean or Extended Boolean The system evaluates all faces involved in a Boolean; hence the result is predictable and all-inclusive. However, if a Boolean involves many faces its execution takes more time than an Extend or a Merge. • Merge or Extend The system evaluates only the faces you specify. Hence execution time is also minimal. However, you must be sure that you have specified all the necessary faces. Intervening faces between an entry face and an exit face are not detected. In general, if you are sure of the faces that are involved in an operation, a Merge or Extend operation may be more appropriate. If you are unsure of how many faces are involved in an operation, a Boolean may be more appropriate. If you find no advantage to choosing a particular application over the others, choose Extended Boolean. Extended Boolean is the most stable of all the applications. NoApply If you specify NoApply (no application), the geometry of the workpiece is not modified. The feature instance is inserted in place and is a separate object. Inserting an Instance System Features 2-16 Feature-based Modeling User Guide and Menu Reference System Features SYSLIB The system supplies a system library, called SYSLIB, that contains all the system features. SYSLIB is always active and is read-only, hence you cannot directly modify a system feature. The Virtual Library You can have access to two libraries at a time: SYSLIB and a single user-defined library. Together, SYSLIB and the user library comprise a virtual library. Example: The following illustration shows a virtual library comprised of the system library and User_Library1. Inserting an Instance System Features Feature-based Modeling User Guide and Menu Reference 2-17 Same Feature Name Exists Across Libraries If the same feature name exists across the two libraries, the feature in the user-defined library overrides the system library. Example: If a feature called Hole exists in both the system library and the user-defined library, the system references the feature Hole in user_library1. The following illustration shows such a case. Inserting an Instance System Features 2-18 Feature-based Modeling User Guide and Menu Reference Library Options Library options are relevant to choosing a user-defined library. Displays the Select Library property sheet. The library you choose from that menu plus the system library comprise the virtual library. Displays the Browse property sheet which is shown in the following illustration. The fields within that menu are as follows: • The Library field accesses a runtime list of libraries. • Once you make a library selection, you can use the Feature field to access a list of features within that library. • Once you choose a feature, a list of its attributes appears. Inserting an Instance System Features Feature-based Modeling User Guide and Menu Reference 2-19 • View Feature Mode allows you to view a feature, of the active library, before you actually insert it. View Feature Mode was discussed earlier in this chapter on page 2-4. Setting the Tolerance Value for System Library Features The system library features used in the Metric part now use the tolerance value of 0.05 mm instead of the previous default tolerance value that was specified in inches. Set an appropriate Epsilon value in the configuration part (c_part) so that you can also use a flexible tolerance (Epsilon) value for the system library features in a Metric part. See Managing CADDS 5i for details on creating a configuration part. Please note: You cannot set a flexible tolerance value for user-defined features because these features can have specific tolerance settings that you want to preserve. Use the following steps to set the tolerance value for the configuration part: 1. Specify the required tolerance value in the configuration part. 2. Set the value of the environment variable PARTS_SR to the configuration part to use the set tolerance value, in the .caddsrc-local file. For example, setenv PARTS_SR /home/<user_id>/parts/config/parts Inserting an Instance System Features 2-20 Feature-based Modeling User Guide and Menu Reference After you complete thses steps, if you insert a system library feature in an active part, the tolerance value you specified is used. If you do not set the value of the environment variable PARTS_SR, the default tolerance value of 0.05mm is used when you insert a system library feature in a Metric part. Inserting an Instance Categories of System Features Feature-based Modeling User Guide and Menu Reference 2-21 Categories of System Features System features can be categorized as additive or subtractive. For example, the system feature Hole is a subtractive feature because it subtracts material from a workpiece, while the system feature Boss is additive because it adds material to a workpiece. Some subtractive features can be further categorized as thru holes, cutouts, flats, grooves, and slots. Additive Features Additive system features are protrusions on the face of a workpiece. Note the following regarding additive features: • The key attribute of additive features is their height above the exit face. • An additive feature protrudes along the positive z-axis and its origin is at the base of the protrusion. • You can apply an additive feature with all four application types (Extend, Merge, Boolean, Extended Boolean) or specify no application. If you use an Extend, a Merge, or an Extended Boolean option, you must select an exit face. Example The following illustration shows an instance of the additive feature Boss_Circular and its key attributes. Inserting an Instance Categories of System Features 2-22 Feature-based Modeling User Guide and Menu Reference The following are the formal names for system features that are additive: • Boss_Circular • Tab_Rectangular Subtractive Features Subtractive system features are depressions in the face of a workpiece. Note the following regarding a subtractive feature: • The key attribute is its depth into the entry face. That depth is oriented along the negative z-axis. • The origin is on the entry face at the center of the opening. • You can apply a subtractive feature using all four application types or specify NoApply. If you use an Extend, Merge, or Extended Boolean operation, you must specify an entry face. Example The following illustration shows an instance of the subtractive feature Hole_Blind and its key attributes. Inserting an Instance Categories of System Features Feature-based Modeling User Guide and Menu Reference 2-23 The following are the formal names for system features that are subtractive: • Counterbore • Countersink • Hole_Blind • Hole_Csunk • Hole_CsunkConical • Hole_CsunkRound • Hole_ConicalBottom • Hole_RoundBottom • Hole_Cbored • Hole_CboredConical • Hole_CboredRound • Pocket_Rectangular Thru Holes and Cutouts Thru holes and cutouts are subtractive but, more specifically, they are passages through a workpiece. Note the following regarding thru holes: • The key attributes are the entry face and exit face and the passage is along the negative z-axis into the entry face. • The origin is on the entry face, at the center of the opening. • You can apply a thru hole or cutout with a Merge, an Extend, or Extended Boolean. • You must select an entry face and an exit face. (Note that a Boolean and a NoApply do not utilize the entry face and exit face and thus may not produce a correct geometric representation of a passage.) Inserting an Instance Categories of System Features 2-24 Feature-based Modeling User Guide and Menu Reference Example: The following illustration shows an instance of a thru hole and its key attributes. The following are the formal names for system features that are passages: • Cutout_Circular • Cutout_Rectangular • Hole_Through • Hole_CsunkThru • Hole_CboredThru Flats and Grooves Flats and grooves are subtractive, but more specifically they are depressions on the face of an axial workpiece. The key attributes of grooves and flats are the diameter, which is actually the diameter of the axial workpiece, and the depth of the flat or groove. Note the following regarding the orientation, origin, and application of flats and grooves. • Orientation: • The orientation of a flat is such that the z-axis is perpendicular to the center line of the axial workpiece and the x-axis runs along the center line of the axial workpiece. • The orientation of a groove is such that the z-axis runs along the center line of the axial workpiece. Inserting an Instance Categories of System Features Feature-based Modeling User Guide and Menu Reference 2-25 • Origin: • The origin of a flat is the middle of the entry face at the center of the opening. • The origin of a groove is on the workpiece axis at the center of the groove. • Application: • You can apply flats with any of the four applications. • You can apply a groove with a Boolean application or you can specify no application. Example: The following illustrations shows an instance of a flat and a groove inserted into an axial workpiece. Figure 2-8 Instance of a Flat Warning Be aware of the following restrictions when you use a Merge or Extend to insert an instance of a flat into an axial workpiece. If you cannot comply with these restrictions, use a Boolean application. • The depth must be less than half the diameter of the workpiece. • The length must not extend to an outer face of the workpiece. Inserting an Instance Categories of System Features 2-26 Feature-based Modeling User Guide and Menu Reference Figure 2-9 Instance of a Groove The following are the formal names for system features that are either flats or grooves: • Flat • Flat_Tapered • Groove_Rectangular Full and Partial Slots Slots are depressions in a workpiece. You can insert a slot that passes either fully or partially through a workpiece. Note the following regarding the key attributes, orientation, origin, and application of full and partial slots. • Key attribute: • The key attribute for a partial slot is its length. • The key attribute for a full slot is its exit face. Inserting an Instance Categories of System Features Feature-based Modeling User Guide and Menu Reference 2-27 • Orientation: • The orientation of both slot types is such that the z-axis runs out of the top face, the face on which the slot runs through, and the y-axis runs into the entry face. • Origin: • The origin of both slot types lies on the entry face at the top, center of the opening. • Application: • You can apply a partial slot using any of the four application types or specify no application. Note that Merge, Extend, and Extended Boolean require the attributes EntryFace and TopFace. • Full slots require that you select an entry face, an exit face and a top face. Thus for full slots you can only select a Merge, Extend, or Extended Boolean. (Note that a Boolean and a NoApply do not utilize the entry face, top face, and exit face and thus may not produce a correct geometric representation of a full slot.) Example: The following illustrations show an instance of a full slot and an instance of a partial slot inserted into the same workpiece. Figure 2-10 Full Slot Inserting an Instance Categories of System Features 2-28 Feature-based Modeling User Guide and Menu Reference Figure 2-11 Partial Slot The following are the formal names for system features that are either full or partial slots: • Slot_FullRectangular • Slot_PartialRectangular System Feature Options from the Features Task Set The following lists the system feature options on the Features task set. Options in red: Some options within the Features menu display menus with options highlighted in red. You must choose and provide a value for those highlighted options. Inserting an Instance Categories of System Features Feature-based Modeling User Guide and Menu Reference 2-29 Description of Options Displays the Hole property sheet. Displays the Circular Boss property sheet. Inserting an Instance Categories of System Features 2-30 Feature-based Modeling User Guide and Menu Reference Displays the Counterbored Hole property sheet. Displays the Rectangular Tab property sheet. Inserting an Instance Categories of System Features Feature-based Modeling User Guide and Menu Reference 2-31 Displays the Countersunk Hole property sheet. Displays the Rectangular Pocket property sheet. Inserting an Instance Categories of System Features 2-32 Feature-based Modeling User Guide and Menu Reference Displays the Counterbore property sheet. Displays the Rectangular Slot property sheet. Inserting an Instance Categories of System Features Feature-based Modeling User Guide and Menu Reference 2-33 Displays the Countersink property sheet. Displays the Rectangular Groove property sheet. Inserting an Instance Categories of System Features 2-34 Feature-based Modeling User Guide and Menu Reference Displays the Conicalbottom Hole property sheet. Displays the Flat property sheet. Inserting an Instance Categories of System Features Feature-based Modeling User Guide and Menu Reference 2-35 Displays the Roundbottom Hole property sheet. Displays the Cutout property sheet. Inserting an Instance Categories of System Features 2-36 Feature-based Modeling User Guide and Menu Reference Displays the Countersunk Roundbottom Hole property sheet. Displays the Counterbore Roundbottom Hole property sheet. Inserting an Instance Categories of System Features Feature-based Modeling User Guide and Menu Reference 2-37 Displays the Countersunk Conicalbottom Hole property sheet. Displays the Counterbore Conicalbottom Hole property sheet. Inserting an Instance Sample Session: Inserting an Instance 2-38 Feature-based Modeling User Guide and Menu Reference Sample Session: Inserting an Instance The following procedure describes how the instance of the system feature Hole_Through was inserted into the solid shown in the illustration below. 1. Choose the Hole option on the Features task set. The property sheet shown appears as shown below. 2. Choose Thru, change the diameter to 0.5, and change the application to Extended Boolean. Inserting an Instance Sample Session: Inserting an Instance Feature-based Modeling User Guide and Menu Reference 2-39 The property sheet updates accordingly. 3. Choose Apply. Inserting an Instance Sample Session: Inserting an Instance 2-40 Feature-based Modeling User Guide and Menu Reference A set of attributes is displayed for which you can assign values. 4. Choose Workpiece. You have specified the first operand for the Boolean subtraction. The instance(s) is the other operand. 5. Choose Display from the pulldown menu that appears to preview the default orientation of the inserted feature relative to the workpiece. 6. Reorient the instance by using the Orientation option and selecting the Cplane called FRONT. Inserting an Instance Sample Session: Inserting an Instance Feature-based Modeling User Guide and Menu Reference 2-41 The instance is now inserted with an orientation relative to the Cplane FRONT. 7. Select an entry face and an exit face. The system extends the instance entry face to the entry face you just selected and likewise for the exit face using the orientation you specified. 8. Choose Go on the pulldown menu. Inserting an Instance Sample Session: Inserting an Instance 2-42 Feature-based Modeling User Guide and Menu Reference The system inserts an instance. Since no origin was specified, the system uses the default, which is the [0,0,0] of the selected orientation. The following illustration shows the inserted instance. Inserting an Instance Instance Information Retrieval: The Verify Feature Option Feature-based Modeling User Guide and Menu Reference 2-43 Instance Information Retrieval: The Verify Feature Option The Verify Feature option on the Features task set displays a property sheet that provides two options for verifying features. One option, Instance, graphically highlights or displays a report about the feature instances within the current part that meet the conditions you have set. The other option, Class, displays a report about instances of the feature definition (class) you choose. When Instance is Active By default Instance is active. When it is active, the Verify Feature property sheet appears as shown in the following illustration. You can use that property sheet to either display a report or highlight instances that meet the conditions you have set. The following describes the options when Instance is active: • Highlight highlights the instances that meet the conditions you have set. • Report displays a report on instances that meet the conditions you have set. • Instance reports upon the instance you choose. • All Instances highlights or reports upon all feature instances in the part. Inserting an Instance Instance Information Retrieval: The Verify Feature Option 2-44 Feature-based Modeling User Guide and Menu Reference • Class displays a runtime list of feature definitions (classes) within the part. Choose one and choose Apply to highlight or report on all instances of the class you chose. If no class is chosen, all instances are highlighted or reported upon. • Include Subclasses works with Class to include instances that are subclasses of the class you chose. • Specific Conditions activates the Condition Expression box. You can enter a conditional expression directly into the box or you can choose the box to activate the Condition Expression menu. Entering Conditional Expressions You can use any of the following operators when entering a conditional expression: • = • > • < • <= • >= In addition you can use the following conditional operators: • And • Or • Not Inserting an Instance Instance Information Retrieval: The Verify Feature Option Feature-based Modeling User Guide and Menu Reference 2-45 The following illustration shows how you might use the Condition Expression menu to highlight all instances of Boss_Circular that have an attribute called Diameter with a value greater than 6.25. Inserting an Instance Instance Information Retrieval: The Verify Feature Option 2-46 Feature-based Modeling User Guide and Menu Reference The following describes the options within the Condition Expression menu: • Attribute displays a list of attributes of size from which you can choose. • Operator displays a list of operators (=, <, >, and so on) from which you can choose. • Value displays a calculator that you can use to enter a value. • The rectangular box below displays a list of the conditional operators (and, or, not) you can choose to include in your statement. For example, you might construct the following statement: Diameter > 6.25 and Depth < 3. When Class is Active When Class is active, the Verify Feature property sheet appears as shown in the following illustration. You can use that property sheet to display a report about instances of the feature definition (class) you choose. • Feature Classes displays a runtime list of feature definitions (classes) within the virtual library. Choose one and then choose Apply to display a report on the selected feature definition. • Detail and Brief specify the amount of information to be retrieved. Detail includes information about a feature’s superclasses and subclasses while Brief does not. Inserting an Instance Instance Modification: The Change Feature Option Feature-based Modeling User Guide and Menu Reference 2-47 Instance Modification: The Change Feature Option You can modify an instance by changing its attribute values. The Change Feature option allows you to change the attribute values of an instance. You can: • Select an instance graphically or by its tag • Choose an attribute from a list and modify its value • Choose a parametric dimension of that instance and change its value Selecting an Instance If you want to choose an instance by name, activate the Tag toggle and enter the tag of the instance you want as shown in the following example. Use the Verify Feature option on the Features task set to display a report that includes instance tags. Inserting an Instance Instance Modification: The Change Feature Option 2-48 Feature-based Modeling User Guide and Menu Reference If you want to select an instance graphically, choose Select Graphically and select an instance. Once you select an instance, Change Feature blanks all parametric dimensions not associated with that instance and unblanks all parametric associated dimensions. Such blanking allows you to easily recognize only those parameters that are associated with the instance. The following illustration shows an instance of Hole_Blind inserted into a block. Inserting an Instance Instance Modification: The Change Feature Option Feature-based Modeling User Guide and Menu Reference 2-49 The next illustration shows the instance after it has been selected while using the Change Feature option. Notice all parameters have been blanked except those associated to the Hole_Blind instance. Choosing and Modifying Attributes The Change Feature option allows you to change the geometric and non geometric attributes of an instance. However, only attributes of the following types can be changed: • Integer • Cardinal • Real • Length • Radius • Diameter • Angle • HalfAngle • String • Name Inserting an Instance Instance Modification: The Change Feature Option 2-50 Feature-based Modeling User Guide and Menu Reference Warning You cannot use the Change Feature option on the following attribute types: • Location • Vector • Cplane • Entity • Face • Edge • Profile • Instance • Boolean_Op • Applytype You can choose and modify one or more attributes of a selected instance from the Change Feature property sheet. Choose the attribute(s) you want and enter the new value(s) using the calculator that appears. The following illustration shows the Change Feature property sheet while the instance of Hole_Blind is selected. Inserting an Instance Instance Modification: The Change Feature Option Feature-based Modeling User Guide and Menu Reference 2-51 Alternately, you can choose and modify one or more attributes of a selected instance by specifying parametric dimension(s) and entering a new value using the calculator that appears. The following illustration shows the Hole_Blind instance in a selected state and indicates that you can select either or both the depth or diameter parameter of the instance. All other parameters are blanked. Whether you choose and modify an attribute from the list or by its parameter, the Change Attribute option responds by Highlighting the parameter attribute. (Red is the default highlighting color for changed parameters). You must then 1. Choose Apply. The following illustration shows the Hole_Blind instance with its Depth attribute changed from its initial value of 0.50 to 0.75. Inserting an Instance Instance Modification: The Change Feature Option 2-52 Feature-based Modeling User Guide and Menu Reference 2. Choose the Regenerate Model option. The system responds by regenerating the instance according to the modified values. In the case shown, the depth becomes .75. Notice how all parameters are again visible. Feature-based Modeling User Guide and Menu Reference 3-1 Chapter 3 Creating a Feature This chapter explains how to create a feature. • Overview of User-defined Features • Creating a Definition • Creating a Representation • Sample Session: Creating a Feature Creating a Feature Overview of User-defined Features 3-2 Feature-based Modeling User Guide and Menu Reference Overview of User-defined Features You can create a library of user-defined features and insert an instance of one much like you would for a system feature. The following steps provide a generalized outline of the tasks required to create a user-defined feature: 1. Create a definition with the Define Feature option on the Features task set. 2. Create a representation by conducting a Teach Feature session. Later in the same Teach Feature session you can associate particular attributes from the definition you specify to particular entities, parametric dimensions, parametric labels, or user dimensions. You do not have to approach these tasks in a completely linear fashion. You can, for example, create consecutive definitions and then create a representation part for each respective definition. Please note: You must create a definition before creating a representation for that definition. You can use the sketches created in the Sketcher environment to create user defined features as part of the feature libraries. Using Sketcher in Feature's "Teach" mode, you can create 2D shapes which can then be used to create 3D geometry as part of feature definition. Modifying a Definition You can modify an existing definition. However, under certain conditions, the system locks that definition’s representation. Locking prevents you from inserting an instance of the representation. The system locks the representation of a definition if you make any of the following modifications: • Delete a superclass • Delete an attribute of size or a face attribute • Change an existing attribute’s data type Under those conditions the system locks the modified definition’s representation along with the representations of any of its subclasses (any of its descendant subclasses). Creating a Feature Overview of User-defined Features Feature-based Modeling User Guide and Menu Reference 3-3 Modifying a Representation You can modify an existing representation. Existing instances of that feature are not affected by the modifications. Subsequent instances of that feature reflects the modifications. Creating a Feature Creating a Definition 3-4 Feature-based Modeling User Guide and Menu Reference Creating a Definition Creating a definition allows you to specify a set of attributes customized to your design needs. You can utilize a system feature definition as a superclass or choose an existing user-defined feature definition. Overview of the Process You can create a definition within the Local Data Manager or while a part is active. For each definition you create, you must complete the following tasks: 1. Choose the Define Feature option from the Features task set. 2. Choose a user library. The definition you create is saved in that library. By default it is created in the current library. 3. Enter a definition name. If the feature is new, specify a unique name. A feature name can have a maximum of 29 characters and its first character must be a letter. 4. (Optional) Choose a superclass(es). If you specify a superclass, the definition inherits all the attributes of that superclass. By default, your definition is a subclass of the system class Feature. You can, however, change that default. 5. Enter attributes. Entering Attributes Entering an attribute requires that you specify the following items: • The name of the attribute. This item is a unique string, within a definition, that identifies the attribute. • The type. This item specifies a data type (integer, string, and so on) so that only a valid value can be assigned to the attribute. For example, if you define an attribute called thickness and identify it as the type integer, then attempt to assign to it a non integer value, that value is not accepted. • The default value of an attribute. This item assigns a default value to an attribute in accordance with the following conditions: • Attributes of size are typically assigned a value during definition. • Static attributes cannot have their values changed when you insert an instance. • Dynamic attributes have a value that is simply a default that you can change when you insert an instance. Creating a Feature Creating a Definition Feature-based Modeling User Guide and Menu Reference 3-5 • Attributes that require a graphical selection cannot have a default value. For example, you cannot assign a default to the attribute workpiece as it requires a graphical selection when you insert an instance. • The units. This item specifies the units used by an attribute of size. • The material condition. This item indicates how increasing the value of an attribute of size affects the amount of material in the workpiece once you insert an instance of the feature. That effect can be any of the following: • Less material, a negative (-) condition • More material, a positive (+) condition • Same amount of material, an equivalent (=) condition Please note: The system does not allow you to mix properties and features within the same library. Properties are discussed in Chapter 4, “Using Properties.” Options Related to Creating a Definition The following options are relevant to creating a definition and are on the Features task set. Description of Options Creating a Feature Creating a Definition 3-6 Feature-based Modeling User Guide and Menu Reference Displays the Select Library property sheet. The library you select from that property sheet plus the system library comprise the virtual library. Displays the Define Feature property sheet, which is shown on the next page. The fields within that property sheet are as follows: • The Selected Library field displays the current user library and accesses a runtime list from which you can choose another library. • The Feature field allows you to enter a name for the feature you are currently defining and provides access to a runtime list of existing feature definitions within the system library and the user library you choose. • The Super Classes field provides a runtime list of feature definitions from which you can choose a superclass. • The Inherited Attributes field lists static and dynamic attributes inherited from the superclass(es) of the current definition. • The Static Attributes field allows you to add, change, or delete a static attribute by means of the plus, delta, and delete icons. • The Attributes field allows you to add, change, or delete an attribute by means of the plus, delta, and delete icons. Creating a Feature Creating a Definition Feature-based Modeling User Guide and Menu Reference 3-7 Areas of the Define Feature property sheet are hazed to indicate that you are not allowed to modify a SYSLIB feature definition. If a user library were the selected library, those areas would not be hazed and you would be allowed to modify a definition in that library. Please note: Once you choose Apply, the system automatically checks to ensure that the current library contains only feature definitions or is empty. If it contains properties, the system does not allow you to apply the property sheet. Creating a Feature Creating a Definition 3-8 Feature-based Modeling User Guide and Menu Reference You Can Create a Definition in the LDM You can also create a definition entirely within the LDM. The LDM includes a Features/Properties page and a Parts page. The system defaults to the Parts page. To display the Features/Properties page, choose the LDM MODE option, and then choose the FEATURES/PROPETIES option from the displayed list. Once you have the LDM Features/Properties page up, choose Active Mode, choose Define and choose Define New Feature/Property. If the current library is empty, the system displays the Define Feature/Property menu. choose Feature and the system displays the Define Feature property sheet. Creating a Feature Creating a Definition Feature-based Modeling User Guide and Menu Reference 3-9 Library Options in the LDM By choosing the LIBRARY MANAGEMENT option you can display the options shown in the following illustration: The Library Management options have the following functions: • Add Library adds a storage area for features by adding a library to the LDM database. • Delete Library deletes a library from the LDM database. If you use the Contents modifier, this option deletes a non empty library. Any definitions and representations in the specified library are deleted. Without the modifier, the Delete Library option deletes only empty libraries. • Copy Library saves or restores a features library to or from LDM or tape. For more details refer to Appendix D, “Setup Procedures.” Multiple Inheritance Basic Concept It is possible for one superclass to have multiple subclasses and for one subclass to have multiple superclasses. The latter concept is called multiple inheritance. Multiple inheritance is an advanced object-oriented capability not typically needed but available and useful for complex feature definitions. Example: In the following illustration, • Class 2 and Class 3 are subclasses of Class 1. • Class 4 and Class 5 are subclasses of Class 2. • Class 5 and Class 6 are subclasses of Class 3. • Class 5 is a subclass of both Class 2 and Class 3 and thus is a case of multiple inheritance. Creating a Feature Creating a Definition 3-10 Feature-based Modeling User Guide and Menu Reference Note that the bottom level classes (Classes 4, 5, and 6) are all indirectly subclasses of Class 1. Conflicts across Superclasses A precedence scheme resolves any conflicts across superclasses. That precedence scheme works as follows: • If attributes of the same name exist across superclasses, precedence goes to the first specified superclass. Example: In the following illustration, Class 1 and Class 2 are both superclasses of Class 3. If both Class 1 and Class 2 contain an attribute of the same name, precedence goes to the first superclass specified. Thus if Class 1 was the first to be specified as a superclass, Class 3 inherits the common attribute from Class 1. • If an attribute of a given name and type exists in a superclass, you cannot specify an attribute having the same name but having a different type. Example: Assume you are creating a definition called counterbore_hole and specify that counterbore_hole is a subclass of hole. Assume that hole contains an attribute called radius of type integer. You cannot then specify an attribute for counterbore_hole called radius of type length. • An inherited, dynamic attribute can be overwritten when you are creating a feature definition. Creating a Feature Creating a Definition Feature-based Modeling User Guide and Menu Reference 3-11 Example: Assume you are creating a definition called tapered_shaft and specify that tapered_shaft is a subclass of shaft. Assume that shaft contains the dynamic attribute length. You can then create an attribute for tapered_shaft called length which takes precedence (that is, overwrites) the default value of the attribute length inherited from shaft. Utilizing Inheritance You can utilize inheritance when you define your own features. Try to characterize the feature you wish to create and make it a subclass of existing features that have those characteristics. Example: If you are defining a protrusion, make it a subclass of existing features that have characteristics appropriate for a protrusion. See Appendix A, “Taxonomy of System Features,” which describes system feature taxonomy, to help you choose an appropriate superclass. The System Superclass Feature What is the Class Feature? By default, all system features are a subclass of the class Feature and any feature definition you create is by default a subclass of Feature. You can change that default. Feature contains these attributes: origin, orientation, workpiece, application, operation, and representation. See Appendix A, “Taxonomy of System Features” for a taxonomy chart of system features. Changing the Default If you are defining a feature and change the default so that your definition is not a direct subclass of Feature and then select another feature as a superclass, your feature remains a subclass of Feature. This is because the feature you selected as a superclass is itself a subclass of Feature. If Feature is not an Appropriate Superclass In some cases Feature may not be an appropriate superclass. In such a case select an appropriate superclass and remove Feature from your definition’s list of superclasses. Creating a Feature Creating a Definition 3-12 Feature-based Modeling User Guide and Menu Reference Example: If you are defining an additive feature like a boss you should be aware that the default value for the attribute operation in Feature is set to Boolean subtract. A Boolean subtract is an inappropriate application for an additive feature. Thus you should select the feature Boss, which has its attribute operation set to Boolean union, as a superclass. Since Boss is a descendent of Feature, the system would automatically remove Feature from the list of superclasses of the additive feature being defined. The System Superclass Primitive When you use the Define Feature option, the system superclass Feature is automatically listed as a superclass of the feature you are defining. If you are using the Define Feature option to define a primitive, simply change that superclass listing from Feature to Primitive. The system class Primitive does not allow the specification of a workpiece and application is always a NoApply. Creating a Feature Creating a Representation Feature-based Modeling User Guide and Menu Reference 3-13 Creating a Representation Creating a feature representation allows you to determine exactly what an instance will look like and how that representation will relate to its definition. Overview of the Process Conducting a Teach Feature session to create a representation involves the following tasks: 1. Choose the Teach option within the Features page of the Local Data Manager. 2. Choose an existing definition from the list displayed on the Features page. 3. Open a Teach part and then create a geometric representation of the feature. 4. Associate the entities, dimensions, labels, or variable names to the attributes of a particular definition. These associations are stored in the representation. 5. Exit the Teach Feature session. Associating Attributes to a Representation When you issue modeling commands during the Teach session, you create entities, dimensions, and perhaps labels or variable names. You must link, by means of a graphical selection, a particular attribute with a particular entity, dimension, or label. For example, you can link the attribute length with a particular dimension. Be aware of the following when you associate attributes: • You cannot associate an attribute of a particular type with an inappropriate dimension. For example, you cannot associate an attribute of type length with an angular dimension. If you attempt to do so, an error message is displayed. • You should complete representation geometry creation before associating workpiece and entry/exit face. If you have edited the representation geometry, list the attributes to check that associations you made with graphical selections are still valid. • You can use the Disassociate Attribute option to break the association between an attribute and its associated parametric dimension, label, or user dimension. • When you first enter a Teach Feature session, the default active Cplane is Top and hence the value of orientation is Top. If you then use the Define Orientation option to select another Cplane, that Cplane becomes the value for orientation. You can define an orientation any time during a Teach Feature session. Creating a Feature Creating a Representation 3-14 Feature-based Modeling User Guide and Menu Reference • The representation geometry you associate to the attribute workpiece determines that feature’s geometry. Other geometry can exist within the teach part. When you insert an instance only the associated geometry is applied to the workpiece you select. Multiple selections are possible for the attribute workpiece. • A face attribute accepts only a single face selection. • You should add constraints to a representation after having associated attributes and associated variables. • You do not associate non geometric attributes. • At any time you can determine what is associated to a particular attribute by choosing the Associate Attribute option and selecting an attribute name. The system then highlights either the geometry associated with the face or workpiece attribute or the dimension associated with an attribute of size. User Dimensions and Constraints Sometimes the parametric dimensions and labels the system inserts do not directly correspond to an attribute. To address such a case you can do the following: 1. Insert a user dimension that does directly correspond to the attribute and then associate the user dimension to that attribute. 2. Write an equation that involves the attribute and variables you have associated to existing parametric dimensions. You can write the equation such that changing the user dimension triggers the changing of the parametric dimensions. Once you insert an instance, the constraint equations and variables are hidden, and the user dimension becomes essentially parametric. In fact, an instance displays the user dimension in the configured parametric color. The system remembers the constraint equation set and hence you do not have to maintain it. The “Sample Session: Creating a Feature” on page 3-19 provides an example of this function. Features Having Parametrically Controlled Groups of Entities You might want to create a feature consisting of a parametrically controlled variable number of entities. You may want to change the number within that group during feature insertion. In such a case, make sure that during the Teach Feature session, you create the maximum number of such entitles ever likely to be needed. Creating a Feature Creating a Representation Feature-based Modeling User Guide and Menu Reference 3-15 Example: Suppose you are creating a feature class called Hole_Pattern. • Among Hole_Pattern’s attributes is an attribute called Number. • The attribute Number is of type integer and is associated to the parametric label that controls the number of holes in the pattern. • You think that the maximum number of holes in Number’s pattern need not be more than 3. You should construct a pattern of holes having a parametric label, associated with the attribute Number, that has a value of 3 or higher. When you insert Hole_Pattern, you can change the value of attribute Number only up to that maximum of 3 which you constructed during the Teach Feature session. The following illustration shows what the representation for Hole_Pattern might look like. Exiting a Teach Feature Session and Locking When you exit a Teach Feature session, the Lock/Unlock property sheet appears. That property sheet lists any non associated attributes for the just-exited representation and allows you to lock or unlock the representation. Locking prevents you from inserting an instance of the representation. The system initially locks new representations and representations into which you have copied a part or existing representation. Creating a Feature Creating a Representation 3-16 Feature-based Modeling User Guide and Menu Reference Options Related to Creating a Representation Teach Feature Options within the LDM Two of the Feature Mode options, shown in the following illustration, are related to creating a representation. Those options are TEACH and DELETE. Teach Feature If you choose the TEACH (Feature) option and then choose a user definition that has no representation, the system displays the Teach New Feature property sheet. If you choose the TEACH option and then choose a definition that does have a representation, the system displays the Teach Feature Old property sheet. You can copy an existing representation into the representation you are creating. Likewise, you can copy a part into the representation you are creating. However, that part must not include explicit geometry, feature instances, or any Profile environment geometry whether it has been applied or not. Creating a Feature Creating a Representation Feature-based Modeling User Guide and Menu Reference 3-17 Once you apply the property sheet, a Teach Feature session is activated. The following illustration shows the Teach New Feature property sheet. Creating a Feature Creating a Representation 3-18 Feature-based Modeling User Guide and Menu Reference Options within a Teach Feature Session Displays the Select Library property sheet. The library you choose from that property sheet, plus the System Library comprise the virtual library. Displays the Define Feature property sheet. Use it to define or modify a feature definition during the Teach Feature session. Associates an attribute. Choose an attribute name from the displayed runtime list and then choose a dimension, label, or entity. Remember that allowable entities depend upon the named attribute’s type. Disassociates an attribute. Choose an attribute name from the displayed runtime list of currently associated attributes or select all attributes. Orients the representation relative to the Cplane you select. Displays the Browse property sheet. The Library field accesses a runtime list of libraries. Once you choose a library, you can use the Feature field to access a list of features within that library. Once you choose a feature, a list of its attributes appears. Delete Feature The DELETE (Feature) option allows you to delete a definition or a representation. If you delete a definition, the system automatically deletes its representation (if it has one). You can delete a feature even if you inserted instances of it because DELETE deletes only the global description (its definition and representation) of a feature that exists in the current library. It does not delete the local description created in a part during an Insert Feature action. Instances use that stored local description. You cannot delete a feature that is a superclass of another property. The system will deny such a deletion request. You can delete a feature that itself has superclasses. The system grants such a deletion request. In those cases the system removes references within a superclass to the class you delete. Creating a Feature Sample Session: Creating a Feature Feature-based Modeling User Guide and Menu Reference 3-19 Sample Session: Creating a Feature This section describes the process by which the system feature Hole_ConicalBottom was created. Both the creation of the definition and the representation are described. Remember that you cannot create a feature in the system library SYSLIB. You must create your own library of features using the Add Library option. The Definition Before creating a definition, you should review system feature taxonomy to determine an appropriate superclass. Appendix A, “Taxonomy of System Features” describes the taxonomy for system features. In the case of Hole_ConicalBottom it was determined that an existing feature called Hole_Blind shared its characteristics. Thus Hole_ConicalBottom was made a subclass of Hole_Blind and inherits its attributes. One attribute, TipAngle, was not inherited. It was an addition specific to the definition of Hole_ConicalBottom. The following illustration shows the Define Feature property sheet for Hole_ConicalBottom. Creating a Feature Sample Session: Creating a Feature 3-20 Feature-based Modeling User Guide and Menu Reference Figure 3-1 The Define Feature Property Sheet Creating a Feature Sample Session: Creating a Feature Feature-based Modeling User Guide and Menu Reference 3-21 The Representation Hole_ConicalBottom, when inserted, is subtracted from a workpiece. Its representation is the geometry to be subtracted. For Hole_ConicalBottom, creating that subtractive geometry involves the following: • Inserting a rotational sweep • Adding two user dimensions • Associating attributes • Setting constraint equations • Defining an orientation Appendix B, “Command File for Hole_ConicalBottom,” lists the commands used during the Teach Feature session for Hole_ConicalBottom. The Rotational Sweep A polycurve was inserted and rotationally swept 360°. That profile’s dimensions are shown in the following illustration: Creating a Feature Sample Session: Creating a Feature 3-22 Feature-based Modeling User Guide and Menu Reference The result of the rotational sweep is shown in the following illustration. Note how the three parametric dimensions correspond to the parameters of the swept polycurve. Creating a Feature Sample Session: Creating a Feature Feature-based Modeling User Guide and Menu Reference 3-23 The User Dimensions The rotational sweep did not result in parametric dimensions that directly correspond to the attributes of Hole_ConicalBottom. No appropriate parameter was inserted for the attribute HoleDiameter (a radial dimension was inserted) nor does one exist for the attribute TipAngle (an angular dimension measuring half the tip angle was inserted). Attempting different modeling options to achieve the needed parameters was not necessary. Instead two user dimensions, appropriate for HoleDiameter and TipAngle, were added. Those user dimensions are shown in the following illustration. Creating a Feature Sample Session: Creating a Feature 3-24 Feature-based Modeling User Guide and Menu Reference Association of the Attributes Association of the attributes is the step that links a definition to its representation. The association of the attribute workpiece identifies the geometry to be used when an instance of Hole_ConicalBottom is inserted. Other associations identify the parametric dimensions and user dimensions to be used as driving dimensions of an instance and the face to be mapped to the entry face. The following illustration shows the entity/attribute associations. Creating a Feature Sample Session: Creating a Feature Feature-based Modeling User Guide and Menu Reference 3-25 The Constraints In order to make the two user dimensions (the cone diameter and the tip angle) driving dimensions, they had to be involved in constraint equations with the cone radius and the half tip angle. Those constraint equations are HoleDiameter=2*L1 and TipAngle=2*A1. The variable L1 is associated to the cone radius parametric dimension and the variable A1 is associated to the half tip angle parametric dimension. Once an instance is inserted, the distinction between the parametric dimensions and user dimensions becomes invisible. Since only dimensions associated to attributes are displayed in an instance, A1 and L1 are not visible in an instance. The following illustration shows the representation geometry after the constraint variables are associated and also shows the report window of the variables and constraint equations.