Mastering Autodesk Inventor 2014 and Autodesk Inventor LT 2014: Autodesk Official Press

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Copyright © 2013 by John Wiley & Sons, Inc., Indianapolis, Indiana

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ISBN: 978-1-118-54486-0

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Dear Reader,

Thank you for choosing Mastering Autodesk Inventor 2014 and Autodesk Inventor LT 2014. This book is part of a family of premium-quality Sybex books, all of which are written by outstanding authors who combine practical experience with a gift for teaching.

Sybex was founded in 1976. More than 30 years later, we're still committed to producing consistently exceptional books. With each of our titles, we're working hard to set a new standard for the industry. From the paper we print on, to the authors we work with, our goal is to bring you the best books available.

I hope you see all that reflected in these pages. I'd be very interested to hear your comments and get your feedback on how we're doing. Feel free to let me know what you think about this or any other Sybex book by sending me an email at [email protected]. If you think you've found a technical error in this book, please visit http://sybex.custhelp.com. Customer feedback is critical to our efforts at Sybex.

To Jennifer for all of the love, support, and encouragement.

Acknowledgments

This book is a collaborative effort involving many more people than those listed on the cover. Personally, I would like to thank my family, whose patience and understanding made this, and all other pursuits, possible. Professionally, I would like to thank the coworkers, clients, customers, and friends whose input and ideas have helped build the knowledge and experience that I draw from in applying concept to practice.

I would like to thank Lucas Larue for the outstanding work he performed as technical editor as well as the many tips and tricks he's contributed to this book and my overall knowledge of Autodesk® Inventor® software. A special thank you goes out to those who have contributed content to the Mastering Inventor series in the past: Thom Tremblay, Sean Dotson, Bill Bogan, Andrew Faix, Seth Hindman, Loren Jahraus, Shekar Subrahmanyam, Bob Van der Donck, and the late Dennis Jeffrey, all of whom are true masters of Autodesk Inventor.

Thank you to the team at Wiley—Jim Compton, Dassi Zeidel, Linda Recktenwald, James Saturnio, Connor O'Brien, Willem Knibbe, and Pete Gaughan—for their patience, focus, and professionalism, without which there would be no book. Your hard work and support always ease the effort of turning ideas into pages.

About the Author

Curtis Waguespack is an Autodesk Expert Elite member and an Autodesk Certified Instructor. He has served as lead author on five previous Autodesk Inventor books, covering Autodesk Inventor 2009 through 2013. He has taught Inventor in the classroom and has consulted with and supported manufacturing and design firms in a wide range of industries, including aerospace, consumer products, and industrial machinery. Presently, Curtis uses Inventor daily in a real-world design environment to design and document various product types, starting from the prototype stage and following through to the fully documented project completion. In the past, he has used Inventor to design a wide range of manufactured products, large and small.

Introduction

The Autodesk® Inventor® program was introduced in 1999 as an ambitious 3D parametric modeler based not on the familiar AutoCAD® software programming architecture but instead on a separate foundation that would provide the room needed to grow into the fully featured modeler it is now, over a decade later. Autodesk Inventor 2014 continues the development of Autodesk Inventor with improved modeling, drawing, assembly, and visualization tools. Autodesk has set out to improve this release of Autodesk Inventor by devoting as much time and energy to improving existing tools and features as they have to adding new ones.

With this book, the sixth edition of Mastering Autodesk Inventor and Autodesk Inventor LT, I have set out to update the existing pages and add new content and exercises. In these pages, you will find detailed information on the specifics of the tools and the principles of sound parametric design techniques. Some readers will find this book works best for them as a desktop reference, whereas others will use it primarily for the step-by-step tutorials. With this in mind, I've worked to shape the pages of this book with a mix of reference material, instructional steps, and tips and hints from the real world.

Who Should Read This Book

This book is written with a wide range of Autodesk Inventor users in mind, varying from beginner to advanced users and Autodesk Inventor instructors:

Beginner Autodesk Inventor users who are making the move from traditional 2D CAD design to Autodesk Inventor 2014. These readers might have experience with AutoCAD, and will possess an understanding of basic design and engineering concepts as well as a desire to improve their skill set and stay competitive in the marketplace.

Intermediate Autodesk Inventor users who are self-taught or have gone through formal Autodesk Inventor training during their company's initial implementation of Autodesk Inventor, and are looking for more information on a specific module within Autodesk Inventor. This book also targets users looking for a desktop reference to turn to when they come upon an area of Autodesk Inventor they do not encounter on a day-to-day basis.

Advanced Autodesk Inventor users who have mastered the Autodesk Inventor tools used over and over daily but want to conquer the parts of the program they do not utilize during their normal design tasks. This book also targets advanced users who want to add to their skill set to move up the ranks within their current company or want to expand their knowledge in pursuit of a new position with another employer.

Autodesk Inventor users of any skill and experience level who are preparing for the Autodesk Inventor Associate or Professional exam.

CAD and engineering instructors looking for a text to use in instructor-led classroom training.

Attempting to learn all the tools in Autodesk Inventor can be an intimidating experience because of the wide range of task-specific modules available. It is the goal of this book to separate these modules into easy-to-tackle chapters relating to real-world situations for which the tools were designed while also including chapters on general Autodesk Inventor tools, techniques, and design principles.

What You Will Learn

The following pages will explain the Autodesk Inventor settings while teaching you how each tool functions. Just as importantly, though, these pages are filled with the tips and techniques learned by the experts who spent years using, researching, and discussing the tools in Autodesk Inventor. You should come away from reading this book with a solid understanding of the capabilities of Autodesk Inventor and a strong idea of how to tackle your design challenges in the future, as well as an abundance of time-saving tips and tricks.

What You Will Need

The files needed to complete the tutorial projects in this book can be downloaded from the Sybex website at the following location:

www.sybex.com/go/masteringinventor2014

Download the collection of ZIP files and extract all of the files to a folder on your computer, such as \My Documents\Mastering Inventor 2014. In this folder you will have a subdirectory for each of the 20 chapters, plus a couple of other folders, as well as a file called Mastering Inventor 2014.ipj, as shown here:

Once the files are in place, set the Mastering Inventor 2014 project as the active project by following these steps. Note that if you are using Autodesk Inventor LT, the use of project files does not apply, and you can skip these steps:

1. From within Autodesk Inventor, close any open files.

2. From the Get Started tab, select the Projects button.

3. From the Projects dialog box, select the Browse button.

4. From the Choose Project File dialog box, browse to the Mastering Inventor 2014 folder, select the Mastering Inventor 2014.ipj file, and click Open.

5. Note that the Mastering Inventor 2014 project is denoted with a check mark as being the active project.

6. Click Done to close the Projects dialog box. Now you are ready to get started.

Free Autodesk Software for Students and Educators

The Autodesk Education Community is an online resource with more than five million members that enables educators and students to download—for free (see website for terms and conditions)—the same software used by professionals worldwide. You can also access additional tools and materials to help you design, visualize, and simulate ideas. Connect with other learners to stay current with the latest industry trends and get the most out of your designs. Get started today at www.autodesk.com/joinedu.

To install and run Autodesk Inventor, you should consult the system requirements information found on the installation media and ensure that you have a system capable of running Autodesk Inventor adequately. For basic educational purposes, dealing with small tutorial-sized assemblies, Autodesk recommends a minimum of 2 GB of RAM and 16 GB of available hard disk space to accommodate the installation files and temporary files created during the installation. Note that these are the minimum requirements to install and run the program, and you might see slow performance when executing operations that require heavy calculations.

I recommend a system with a minimum of 6 GB of RAM for doing production work on moderate-sized assemblies, and encourage you to consider an appropriate workstation for undertaking large assembly design.

The Mastering Series

The Mastering series from Sybex provides outstanding instruction for readers with intermediate and advanced skills in the form of top-notch training and development for those already working in their field, as well as clear, serious education for those aspiring to become pros. Every Mastering book includes the following:

Real-world scenarios, ranging from case studies to interviews, that show how the tool, technique, or knowledge presented is applied in actual practice

Skill-based instruction, with chapters organized around real tasks rather than abstract concepts or subjects

Self-review test questions, so you can be certain you're equipped to do the job right

What Is Covered in This Book

This is what the book covers:

Chapter 1, Getting Started With Autodesk Inventor, introduces the Autodesk Inventor interface, project setup, and the concept of parametric 3D design.

Chapter 2, A Hands-on Test Drive of the Workflow, explores the general workflow of modeling parts, creating detailed drawings of those parts, assembling those parts, and then detailing the assembly.

Chapter 3, Sketch Techniques, explores the principles of creating parameter-driven sketches for use in modeling features and parts.

Chapter 4, Basic Modeling Techniques, conquers creating parametric features and building 3D parts models.

Chapter 5, Advanced Modeling Techniques, explores complex feature creation, including sweeps, lofts, and more.

Chapter 6, Sheet Metal, covers how to create accurate sheet-metal models and flat patterns as well as how to create documentation and set up sheet-metal styles and templates.

Chapter 7, Reusing Parts and Features, examines the different methods for reusing parts and features for maximum consistency and design efficiency.

Chapter 8, Assembly Design Workflows, gives you a thorough understanding of this key concept of Autodesk Inventor design, including the use of Assembly constraints, subassemblies, and more.

Chapter 9, Large Assembly Strategies, explores tips and techniques to getting the best performance out of your Autodesk Inventor workstation and considers upgrade requirements for the future.

Chapter 10, Weldment Design, explores the Autodesk Inventor weldment modeling environment and the weldment documentation tools.

Chapter 11, Presentations and Exploded Views, gives you a thorough look at the presentation tools used to create exploded assembly views and animated assembly instructions.

Chapter 12, Documentation, covers how to use the Drawing Manager to create traditional 2D annotated drawings.

Chapter 13, Tools Overview, examines this collection of Autodesk Inventor utilities, including AutoLimits, the Design Assistant, the Drawing Resource Transfer Wizard, style tools, and much more.

Chapter 14, Exchanging Data with Other Systems, shows the available options for importing and working with solid models from other CAD packages.

Chapter 15, Frame Generator, covers how to get the most out of this utility when creating structural frames from the Autodesk Inventor library of common shapes.

Chapter 16, Inventor Studio, covers this powerful toolset to create photorealistic images and animations of all your Autodesk Inventor models.

Chapter 17, Stress Analysis and Dynamic Simulation, explores the simulation tools used to analyze load stress and mechanism motion on your models.

Chapter 18, Routed Systems, covers the cable and wire harness and tube and pipe environments and their uses in creating routed design layouts.

Chapter 19, Plastics Design Features, explores the tools used specifically for plastics design as well as the general tools used in specific ways for plastics design. Also included is the Autodesk Inventor Tooling module used to design mold tooling for plastic-part design.

Chapter 20, iLogic, introduces and explores the iLogic tools used to customize, configure, and automate your Autodesk Inventor design files. This chapter provides a solid foundation in the rules-based iLogic programming toolset and interface, allowing you to move forward with your advanced automation and configuration goals.

Appendix A, The Bottom Line, gathers together all the self-testing Master It problems from the chapters and provides a solution for each.

Appendix B, Autodesk Inventor Certification, points you to the chapters in this book that will help you master the objectives for each exam.

Autodesk Inventor LT, Autodesk Inventor, and Autodesk Inventor Professional

The Autodesk Inventor mechanical CAD software is available in three primary product configurations that offer specific levels of functionality to fit the needs of different users. This book contains information that relates to all three of these versions of the Autodesk Inventor software. Depending on the version you have installed, you might find that parts of this book are relevant to your version. For instance, if you have Autodesk Inventor LT installed, you will find that Chapter 8 of this book will not apply to your version, since Autodesk Inventor LT does not include tools used for assembly design. Similarly, if you have Autodesk Inventor installed, you'll find that Chapter 17 does not apply to your version, since that chapter addresses tools found only in Autodesk Inventor Professional. To gain a better understanding of your version of the Autodesk Inventor software and how it relates to each subject in this book, please refer to the feature comparison matrix provided by Autodesk online. You can find this by visiting the Autodesk website and clicking the Features link.

How to Contact the Author

I welcome your feedback concerning Mastering Autodesk® Inventor® 2014 and Autodesk® Inventor LT™ 2014. I want to hear what you liked, what you didn't, and what you think should be in the next edition. And if you catch me making a mistake, please tell me so that I can fix it on the errata page (available at www.sybex.com/go/masteringinventor2014) and in reprints. Please email me at [email protected], or contact Wiley customer service at http://support.wiley.com.

Thank you for purchasing Mastering Autodesk® Inventor® 2014 and Autodesk® Inventor LT™ 2014. I hope it helps you on your way to happy and successful inventing, and I look forward to hearing your comments and questions. You can find additional tips and tricks online at my blog spot, http://inventortrenches.blogspot.com/, and by visiting the Autodesk Discussion Groups at http://forums.autodesk.com/.

Chapter 1

Getting Started with Autodesk® Inventor®

In this chapter, you will be introduced to the concept of parametric 3D design and the general tools and interface of Inventor. This chapter will focus on the concepts of parametric modeling and the workflow, tools, and interface elements found in the Autodesk® Inventor® software that are used to turn your ideas into a design.

In this chapter, you'll learn to:

Create parametric designs

Get the feel of Inventor

Use the Inventor graphical interface

Work with Inventor file types

Understand how project search paths work

Set up library and Content Center paths

Create and configure a project file

Determine the best project type for you

Understanding Parametric Design

Autodesk Inventor is first and foremost 3D parametric modeling software. And although it has capabilities reaching far beyond the task of creating 3D models, it is important for you to understand the fundamentals of parametric 3D design. The term parametric refers to the use of design parameters to construct and control the 3D model you create. For instance, you might begin a design by creating a base sketch to define the profile of a part. In this sketch you would use dimensions as parameters to control the length and width of the sketch. The dimensional parameters allow you to construct the sketch with precise inputs.

Creating a Base Sketch

Well-constructed parts start with well-constructed sketches. Typically, the 3D model starts with a 2D sketch, which is assigned dimensions and 2D sketch constraints to control the general size and shape. These dimensions and constraining geometries are the parameters, or input points, that you would then change to update or edit the sketch. For instance, Figure 1.1 shows a base sketch of a part being designed.

Figure 1.1 Creating a parametric model sketch

You can see four dimensions placed on the two rectangles defining the length and width of each along with a fifth dimension controlling the angle at which the two rectangles relate. These dimensions are parameters, and if you were to change one of them at any point during the design or revision of the part, the sketch would update and adjust to the change.

An important part of working with sketches is the concept of a fully constrained sketch. Fully constrained simply means that all of the needed dimensions and sketch constraints have been applied to achieve a sketch that cannot be manipulated accidentally or as an unintentional consequence of an edit. For instance, if you were to sketch four lines to define a rectangle, you would expect two dimensions to be applied, defining the length and width. But you would also need to use 2D sketch constraints to constrain the lines so that they would stay perpendicular and equal to one another if one of the dimensions were to change. Without the sketch constraints, a dimensional edit to make the rectangle longer might result in a trapezoid or a parallelogram rather than the longer rectangle you anticipated. By fully constraining a sketch, you can anticipate the way in which it will update. Inventor helps you with this concept by automatically applying many sketch constraints, and by reporting when a sketch is fully constrained. This will be covered in more detail in Chapter 3, Sketch Techniques.

Creating a Base Feature

Not only do you add 2D sketch parameters; you also add parameters to control the 3D properties of parts. This is done by using the sketch to create a feature such as an extrusion to give a depth value to the sketch. The depth dimension is a parameter as well, and it can be updated at any time to adjust the part model as required. Figure 1.2 shows the sketch from Figure 1.1 after it has been given a depth using the Extrude tool.

Figure 1.2 A basic part model created from the sketch

Adding More Features

Once the part is three-dimensional, more sketches can be added to any of the faces of the 3D shape, and those new sketches can be used to create some feature that further defines the form and function of the design. The model is then enhanced with more features, such as holes, fillets, and chamfers, until it is complete. Each added feature is controlled by still more parameters defined by you, the designer. If a change is required, you simply update the parameter and the model updates accordingly. This type of parametric design allows you to build robust and intelligent models very quickly and update them even faster. Figure 1.3 illustrates the typical workflow of adding secondary features to a base feature to fully realize the part design, in this case a simple pivot link.

Figure 1.3 Adding features to complete the part model

Using the Part in an Assembly

Just as well-constructed parts start with well-constructed sketches, well-constructed assemblies start with well-constructed parts. Once the part model is built up from the features you create, you can use it in an assembly of other parts created in the same manner. You can copy the part to create multiple instances of the same part, and you can copy the part file to create variations of the original part. To assemble parts, you create geometric relationships called assembly constraints defining how the parts go together. The constraints are parameters that can be defined and revised by you at any time in the design process as well. Part models can be arranged into small assemblies and placed into larger assemblies to create a fully realized subassembly structure that matches the way your design will be built on the shop floor. Figure 1.4 shows the part model from the previous illustrations placed multiple times in a subassembly, and then that subassembly placed in a top-level assembly.

Figure 1.4 A subassembly and an assembly model using the part model

Making Changes

Once parts are created, they are then used in assemblies, which also employ parameters to define the offsets and mating relationships between assembled parts. Designing with the use of parameters allows you to make edits quickly and lends itself to creating product configurations, where parameter values are changed to create variations of a basic design.

Of course, as with building anything, there are general rules and best practices to be learned and followed to prevent your work from falling apart. For instance, what if the pivot link used in the previous examples were to incur a design change that made one leg of the link longer? How would the holes be affected? Should they stay in the same place? Or should they stay at some defined distance from one end or the other?

Anticipating changes to the model is a large part of being successful with Inventor. Imagine, for instance, that a simple design change required that the pivot link become 50 millimeters longer on one leg. This should be a simple revision that requires you only to locate the dimension controlling that leg length and change the parameter value. Unfortunately, if you did not follow the best-practices guidelines when creating the part originally, the change in the length might displace the secondary features such as holes and material cuts and require you to stop and fix each of those as well. This is one of the most frustrating parts of learning Inventor for any new user who has not taken the time to learn or follow the known best practices of parametric modeling. Fortunately for you, within the pages of this book you will learn how to create models that are easy to update and do not fall apart during design changes.

Understanding History-Based Modeling and Dependencies

Inventor is often referred to as a history-based modeler, meaning that as you create sketches and turn them into features and then add more features and still more features, each addition is based on a previous feature, and so the model is said to have history. This history is recorded and tracked in the Model browser. The Model browser is a panel that displays on-screen and shows every feature you create during the design of your part. Figure 1.5 shows the Model browser for the pivot link file.

Figure 1.5 The Model browser showing the feature tree (history) of a part named Pivot_Link.ipt

You can see that each feature is listed in the browser in the order in which it was created, forming a history tree. To create a part that handles changes predictably, you must create a solid foundation on which to build the rest of the model. In most cases, when you are designing a part model you will start with a sketch, much like the one shown back in Figure 1.1. This base sketch will be your foundation, and therefore you must create it to be as stable as possible.

Each part, no matter what it is or what it looks like, has a set of origin geometry in the form of the origin planes, origin axes, and a single origin point. You can find these origin features by expanding the Origin folder in the Model browser. Figure 1.5 shows the Origin folder not expanded. If you expand the Origin folder in any part or assembly file, you will see the following items:

YZ Plane, the plane that runs infinitely in the Y and Z directions

XZ Plane, the plane that runs infinitely in the X and Z directions

XY Plane, the plane that runs infinitely in the X and Y directions

X Axis, the axis running infinitely in the X direction

Y Axis, the axis running infinitely in the Y direction

Z Axis, the axis running infinitely in the Z direction

Center Point, the point found at zero in the X, zero in the Y, and zero in the Z directions

When creating the base sketch of a part file, you typically start on one of the origin planes. Because the origin plane cannot be edited, deleted, redefined, or upset in any manner, this base sketch is inherently stable, and as a result, the base feature you create from it is stable as well. If the second sketch of your part is created on a 3D face of the base feature, this sketch is dependent on the base sketch and is considered slightly less stable than the base sketch. This is because the base sketch could be edited, deleted, or redefined in a way that would upset the secondary sketch.

Understanding how dependencies are created when a sketch and features are based on one another will help you avoid creating a house of cards that will fall apart if the base is upset. Although you could base all of your sketches and features on origin geometry to minimize dependencies, it is generally not practical to do so. It should be your goal, however, to keep the number of chained dependencies to a minimum. Assemblies work in much the same way, using the faces and edges of parts to constrain them together and as a result building dependencies between them. Just like part files, assembly files have origin planes, axes, and a center point that can be used to minimize chained dependencies, thereby creating a more stable model.

Taking a Closer Look at Sketch Dimensions

A large part of creating a stable sketch comes from understanding the way sketch dimensions work in Inventor. To do so, you might compare Inventor dimensions with standard dimensions in Autodesk® AutoCAD® software. When you create a design in AutoCAD, that design process is not much different from creating the same design on a paper drawing. But in AutoCAD, you can draw precise lines, arcs, circles, and other objects and place them precisely and with accurate dimensions reflecting your design in a way that you cannot do by hand. When a design requires modification, you erase, move, copy, stretch, and otherwise manipulate the existing geometry more quickly than you can by hand as well. But other than those gains in speed and accuracy, the workflow is much the same as working with pencil and paper. In short, AutoCAD automates drafting tasks but does less to speed up and enhance the design process. By comparison, Inventor's sketch dimensions allow you to add design parameters and a bit of intelligence to your sketches.

Driven Dimensions

Standard dimensions in AutoCAD are called driven or reference dimensions. A driven dimension is controlled by the geometry, and it reflects the actual value of the geometry being referenced by the dimension. If you stretch a line, for example, the dimension attached to the line will update to the new value. If you think about it, the only reason for a dimension on a traditional AutoCAD drawing is to convey the value of a feature or part to the person who is going to build it. If you import that 2D file into a computer-aided manufacturing (CAM) software, no dimensions are needed because the line work contains all the information about the part.

Parametric AutoCAD

Starting with AutoCAD 2010, you can create 2D parametric dimensions and constraints much as you can in Inventor.

Driving Dimensions

The workflow in Inventor sketching is substantially different from that in traditional AutoCAD, even beyond dimensions. In Inventor, you create sketches in 2D and then add geometric constraints such as Horizontal, Vertical, Parallel, and so on to further define the sketch entities. Adding the geometric constraints allows line work to adjust in a predictable and desired manner and helps control the overall shape of the sketch. Once geometric constraints are in place, you add parametric driving dimensions to the sketch geometry. By changing the value of these driving dimensions, you change or drive the size of the sketch object. Because of this, the Inventor dimension is far more powerful than the standard AutoCAD dimension because it not only conveys the value of a feature or part but also serves as a design parameter, allowing you to change the dimension to update the design. This is done simply by double-clicking the dimension and typing in a new value. Figure 1.6 shows a dimension being edited in a sketch on the left and the result on the right.

Figure 1.6 Editing Inventor sketch dimensions

Part Modeling Best Practices

A solid sketch is the foundation on which stable parts are built. Many new users do not understand the importance of having fully constrained sketches, and they find it highly frustrating to have a model fail when a simple change is made, all because a sketch was not properly constructed. This frustration can be avoided by following some basic best practices.

Keep Sketches Simple

The most effective way to create a healthy sketch is to keep it simple. The purpose of keeping your base sketch simple is to get it fully defined, leaving no part of it up for interpretation. Underdefined sketch entities (lines without defined lengths, circles without defined diameters, and so on) will most likely not update properly and will cause your sketches to distort and break when you try to update them. And because you often base the rest of your model on the initial sketch, your entire feature tree might incur errors, requiring you to stop and spend time rebuilding it again. Examine the sketch in Figure 1.1 and compare it to the finished shape shown in Figure 1.5. As you can see, the simple sketch containing two rectangles dimensioned at an angle defines the basic shape and is much easier to sketch and fully constrain than the finished shape would be.

If the idea of simple sketches seems at first not to fit the type of design you do, understand that most designs will benefit from the simple-sketch philosophy. More important, if you start out employing simple sketches, you will more quickly master the sketch tools and then be ready to create more complex sketches when a design absolutely requires it.

Create Simple Features from Simple Sketches

Another aspect of creating simple sketches is that it allows you to create simple features. Parametric, feature–based modeling relies on the creation of numerous simpler features within the model to achieve a complex design in the end. By creating a number of features within the model, you are able to independently change or modify a feature without rebuilding the entire model. An example of editing a feature would be changing a hole size. If you create a simple rectangular base feature first and then create a hole feature as a secondary feature to that base feature, you can make changes to both independently. By contrast, if you were to include a circle in your base sketch and use that to create the base feature with a circular profile pocket, your hole would no longer be as easily updated.

Pattern and Mirror at the Feature Level

Although there are mirror and pattern (array) tools in the sketch environment, it is generally best to create a single instance of the item in the sketch and then create a feature from it, and create a mirror or pattern feature from that feature. The logic behind this is based on the idea of keeping sketches simple and the anticipation of future edits. Should the mirror or pattern feature need to be updated, it is much easier to update it as a separate feature.

Create Sketch-Based Features and Then Placed Features

Part features can be separated into two categories: sketch-based and placed. Sketch-based features, as you might guess, are created from sketches. Placed features are features such as fillets and chamfers that are placed by using model edges or faces and have no underlying sketch. Issues arise when placed features are created too early in the development of the part because you may then be required to dimension to the placed feature, which creates a weak dependency. For instance, you might place rounded fillet features along the edges of a part. Then you could use the tangent fillet edges to define the placement of a hole. But then if you realize that machining capabilities require a beveled chamfer edge rather than a rounded filleted one and delete the fillet feature, the hole feature is sure to fail because the tangent fillet edges used to define the hole placement no longer exist. Keep this in mind as you create placed features such as fillets and chamfers, and reserve placed features for the end stages of the part.

Understand Dependent and Independent Features

Parametric model features are typically either dependent or independent of one another. A dependent feature is dependent on the existence or position of a previously created feature. If that previously created feature is deleted, the dependent feature will either be deleted as well or become an independent feature. As mentioned earlier, each part file contains default origin geometry defining the x-axis, y-axis, and z-axis of the part. These origin features are used to create the first sketch in every part by default. An independent feature is normally based on an origin feature or is referenced off the base feature.

For instance, to create the base feature for the pivot link, you would create a sketch on a default origin plane, such as the XY plane. Because the XY origin plane is included in every part file and cannot be changed, your base feature is stable and independent of any other features that may follow. To create a hole in the base feature, you would typically select the face of the base feature to sketch on. Doing so would make the hole feature dependent on the base feature. The hole feature is then inherently less stable than the base feature because it relies on the base feature to define its place in 3D space.

Although the specifics of how sketches, features, and parts are created will be covered in the chapters to come, remember these principles concerning part file best practices, and you will find Inventor (and any other parametric modeler) much more accommodating.

Assembly Modeling Best Practices

Once you've created part files, you will put them together to build an assembly. And when you do, you want to build it to be as stable as possible so that if you move, replace, or remove a part, the rest of the assembly will not fall apart. There are two entities to an assembly file: links to the component files (parts or subassemblies) it is made of and the geometric information about how those components fit together. Basic assemblies are not much more than that, and understanding those two concepts will go a long way toward building stable assemblies.

Understand File Linking and Relationships

The assembly file can be thought of as an empty container file to start. Once you place the first part in the assembly, the assembly file contains a link to the file for that part. When you place a second part and fit it to the first, the assembly then contains links to the two files and the information about how those parts go together in this particular assembly. If you decide to rename the first part file, and do so using Windows Explorer, the assembly file will still look for the file by the old name. When this happens, you will be prompted with a file resolution dialog box asking you to locate the file. You can then browse and manually point the assembly to that file, and the assembly will record the new name in its internal link. If you decide to move the second part file to a folder other than its original, the assembly file might again prompt you to find it manually, depending on the folder structure. It should be your goal to never need to resolve file links manually, and understanding this part of how assemblies work is the first step in reaching that goal. In the coming chapters you will learn how to set up Inventor properly so it can find your files.

Always Maintain at Least One Grounded Component

To understand how grounded parts help you build stable assemblies, you should first understand a little about the assembly Model browser. Figure 1.7 shows the Model browser for an assembly model of a small hobby-type CNC router.

Figure 1.7 The Model browser showing the model tree of an assembly named Router.iam

The Model browser shows an assembly named Router Base at the top and under it three other subassemblies named Y-Axis Assembly, X-Axis Assembly, and Z-Axis Assembly. The Z-Axis Assembly is expanded in the browser so you can see the parts it contains as well. You should note that the Router Base subassembly is shown in the browser with a pushpin button. This denotes that this subassembly is grounded, or pinned in place, and its coordinates cannot accidentally change. Keeping one grounded component in each assembly will allow you to fit other parts to it without it moving or rotating off the x-, y-, and z-coordinates.

Recall the old carnival game where you throw a ball at a pyramid stack of metal bottles. To win the game, you had to knock down all the bottles. However, if the bottle in the center on the bottom were nailed down, it would be impossible to win the game, and as a matter of physics, it would be difficult to knock down the bottles next to it. Having a grounded component in your assemblies, one that is nailed down, will likewise keep your assemblies from falling over as you build onto them. By default, the first component you place into an empty assembly file will automatically be grounded. You can unground it and ground another if need be, but you should always maintain at least one grounded component. You can also have more than one grounded component.

Make Your Models Mimic the Manufacturing Process

The simplest advice that new users can receive on the subject of assemblies is to structure them as you would in real life. For example, if in the design you plan to assemble several parts into a transmission and then drop that transmission into a housing, you should make the transmission a subassembly and insert it into the upper-level housing assembly. Alternatively, a new user might place all the parts into one big assembly, only to later realize that subassemblies are needed for the purpose of getting the bill of materials (BOM) organized. This can be accomplished by using the Demote assembly tool to create the subassemblies and then demote the parts from the top-level assembly to these new subassemblies. By making your models mimic the manufacturing process, you can also find possible flaws in your design, such as fasteners that cannot be accessed or areas where parts may interfere with each other during assembly.

In some instances a model will be developed in the research and development (R&D) department and then handed to the manufacturing engineering (ME) department to be built. Although the people in R&D may enjoy the freedom of dreaming up anything they can think of, an effective R&D designer will always think about what can actually be built within the capabilities of the shop floor. Keep this in mind during the initial development cycle, and it will prevent those downstream from having to re-create much of your work. However, if restructuring the components into more or fewer subassemblies is required after the initial design, Inventor has demote and promote tools to assist with that. These tools will be covered in the chapters to come.

Constrain to Origin Geometry

As mentioned earlier in this chapter, each part file has default origin geometry built in. You should build parts around the origin geometry whenever possible. For instance, a transmission has gears, bearings, seals, and so on that are all concentric with the shaft. If you model all the parts so their x-axes will be aligned in the assembly, then you can use the x-axis of each part to constrain to in the assembly and it will be much more stable. However, if you constrain the parts by selecting model features, you run the risk of constraints failing once a revision to a part changes or removes the originally referenced geometry. To build a completely bulletproof assembly, you could constrain the origin geometry of each part to the origin geometry of the assembly. In this way, no matter how the geometry of the parts changes, it will not cause issues with assembly constraints.

You will learn more about how to create assemblies, set up search paths to avoid manual file resolutions, and work with grounded components in the coming chapters, but you should remember these concepts and work to abide by them.

Understanding the Feel of Inventor

To the new user, the ever-changing Inventor interface may seem a bit disorienting. Taking a few minutes to understand why menus and tools change from one context to another will go a long way in getting comfortable with the feel of Inventor and anticipating the way the user interface works. If you've used other applications with the Microsoft ribbon-style interface, you're probably already familiar with much of this context-specific behavior.

Understanding the Intuitive Interface

The overall user interface of Inventor might be called context intuitive, meaning that menus change depending on the task and the environment. Inventor is organized by tools grouped onto tabs, offering only the tools needed for the appropriate task at hand. If you are sketching a base feature, the tools you see are sketch tools. In Figure 1.8, the Sketch tab is active, and the displayed tools are the ones used to create and dimension sketches.

Figure 1.8 The Sketch tab and sketch tools

Upon the completion of a sketch, click the Finish Sketch button on the far right, and you will exit the sketch. The 3D Model tab then becomes active and the Sketch tab is hidden. This allows you to see the tools that are appropriate for the immediate task, and only those tools, without having to hunt around for them among tools that are you are not able to use at the current moment. If you create a new sketch or edit an existing one, the Sketch tab is immediately brought back. Figure 1.9 shows the active 3D Model tab.

Figure 1.9 The 3D Model tab and model tools

When you work with assemblies, the active tab changes to the Assemble tab (as shown in Figure 1.10), allowing you to place components, create new components, pattern them, copy them, and so on. When in the assembly environment, there are also a number of other tabs shown that you can manually switch to (by clicking on them) at any time to use the tools they contain.

Figure 1.10 The Assemble tab and assembly tools

When you create a 2D drawing of parts or assemblies, you are automatically presented with tools needed to create views and annotation. By default, the Place Views tab is displayed because you need to create a view of a model before annotating it. However, you can manually switch to the Annotate tab by clicking it. Figure 1.11 shows the active Place Views tab and the inactive Annotate tab next to it.

Figure 1.11 The drawing tabs and drawing tools

As you can see, the collection of tabs (called the Ribbon menu) changes intuitively with every task or environment you switch to. With this task-based user interface, there is no need to display every possible tool all at once. In the next section, you will explore more of the user interface.

Using General Tools vs. Specific Commands

In this section you'll see how Inventor tools are set up, using AutoCAD tools as a comparison. If you've never used AutoCAD, you can still gain some insight from this section, although you may have to use your imagination concerning the references to AutoCAD. A key difference between AutoCAD and Inventor is that in AutoCAD, many commands are very specific. For example, there are different dimension commands for lines, angles, and circles. In contrast, Inventor has one General Dimension tool that creates the appropriate dimension based on what you select.

For instance, in AutoCAD you might select the horizontal dimension tool to place a dimension on a horizontal line, select the diameter dimension tool to place a dimension on a hole, select a radius dimension tool to place a dimension on a fillet, and so on. But in Inventor you select the General Dimension tool and select a horizontal line, and you get a horizontal dimension; then, without exiting the General Dimension tool, you select a circle, and you automatically get a diameter dimension. And of course to dimension a fillet, you continue with the General Dimension tool, and you will automatically get a radius dimension.

Drawing in AutoCAD Becomes Sketching in Inventor

The fundamental difference between traditional AutoCAD and Inventor is that in AutoCAD you draw and in Inventor you sketch. This difference sounds subtle, but it is very important. In AutoCAD, you likely construct lines precisely to specific dimensions to form the geometry required. In Inventor, you create lines and geometry that reflect the general form and function of the feature and then use constraints and dimensions to coax it into the desired shape. Expecting Inventor to work just like AutoCAD is probably the single biggest stumbling block that experienced AutoCAD users face when starting to use Inventor.

When in Doubt, Right-Click

Inventor is very right-click–driven, meaning that many of the options are context specific and can be accessed by right-clicking the object in question. For instance, if you want to edit a sketch, you right-click the sketch in the browser and choose Edit Sketch. The same is true of a feature. If you want to change a hole feature from a countersink to a counterbore, you right-click it in the browser and choose Edit Feature. You can also right-click many objects in the graphics window, with no need to locate them in the browser. Figure 1.12 shows a typical right-click context menu with the default marking menu option enabled.

Figure 1.12 A typical right-click menu

Also worth mentioning are the options in the context menus. For instance, if you are editing a part in an assembly and want to finish the edit and return to the assembly level, you could use the Return button on the Sketch tab menu, or you could just right-click (taking care not to click any sketch object) and choose Finish Edit from the context menu. Both options do the same thing.

Traditional Right-Click Menus vs. the Marking Menus

When enabled, marking menus replace the traditional right-click context menu. Since marking menus are customizable, this book references the traditional right-click menu, so specific references to items in the right-click menus may need to be interpreted if you choose to use the marking menus or have customized your marking menus. To enable or disable the marking menus, select Customize on the Tools tab of the ribbon and then select the Marking Menu tab. Then check or uncheck the Use Classic Context Menu check box.

Selections from the marking menu can be made in either menu mode or mark mode.

Menu Mode

When you right-click in the graphics window, menu items surround the cursor. Simply click a menu item to select it.

Mark Mode

When you press and hold the right mouse button and immediately move the cursor in the direction of a known menu item, a mark trail appears. Release the mouse button to select the menu item corresponding to the direction of cursor movement in the marking menu.

Using the Graphical Interface

The Inventor graphical interface might be different from what you are accustomed to in other general software applications and even different from other design software. In Figure 1.13, you see the entire Inventor window, which shows a part file open for editing.

Figure 1.13 The complete Inventor screen in part modeling mode

Inventor Title Bar

Starting at the upper left of the Inventor window, you'll see the Inventor button (look for the large I character), which has a drop-down panel similar to the File menu in previous versions. Next to the Inventor button the title bar includes two toolbars:

The Quick Access bar has frequently used tools.

The Help toolbar provides access to help files and Autodesk websites.

You can customize the Quick Access bar for each file type by selecting and deselecting buttons from a list. The list of available tools can be accessed by clicking the drop-down arrow shown on the far right of Figure 1.14.

Figure 1.14 The Inventor button and Quick Access bar

Table 1.1 defines the default Quick Access bar buttons available in part modeling mode.

Table 1.1 Quick Access bar buttons

Graphics Window Tools

Inventor has two sets of tools for manipulating the graphics window:

The ViewCube is used to change the view orientation.

The Navigation bar has tools such as Zoom and Pan.

Exploring the ViewCube

The ViewCube, shown in Figure 1.15, is a 3D tool that allows you to rotate the view. Here are some viewing options:

Figure 1.15 The ViewCube

If you click a face, edge, or corner of the ViewCube, the view rotates so the selection is perpendicular to the screen.

If you click and drag an edge, the view rotates around the parallel axis.

If you click and drag a corner, you can rotate the model freely.

If you click a face to have an orthogonal view, additional controls will display when your mouse pointer is near the cube.

The four arrowheads pointed at the cube rotate the view to the next face.

The arc arrows rotate the view by 90 degrees in the current plane.

If you click the Home button (it looks like a house), the view rotates to the default isometric view. Clicking the drop-down arrow or right-clicking the Home button reveals several options to change the default isometric view behavior. For instance, you can modify the home view to any view you like, and you can reset the front view in relation to your model so the named views of the cube match what you consider the front, top, right, and so on.

Using a Wheel Mouse and 3D-Input Device

Using a wheel mouse with Inventor is recommended. Scrolling the wheel will perform a Zoom In/Out, while pressing the wheel will perform the Pan function. In Inventor, the wheel zoom is reversed from AutoCAD. You can change this setting by clicking Application Options on the Tools tab, selecting the Display tab, and selecting Reverse Direction in the 3D Navigation group.

Another useful tool for navigating in Inventor is a 3D-input device. A popular brand is the Space series made by 3Dconnexion. These devices are small joysticks or pucks that sit on your desk. The user grasps the puck and, by making very slight movements with the device, moves the model on the screen. Pulling, pushing, and twisting the puck allows you to zoom, pan, and orbit the model on-screen. Although you may find these devices awkward at first, most users say they could never work as efficiently without one after just a few days of use.

A Look at the Navigation Bar

Continuing with the interface tour, you'll see the Navigation bar located on the right side of the graphics window. At the top of the bar is the steering wheel. Below the steering wheel are the other standard navigation tools: Pan, Zoom, Orbit, and Look At. Figure 1.16 shows the Navigation bar.

Figure 1.16 The Navigation bar

You can use the Navigation bar's steering wheel to zoom, pan, walk, and look around the graphics area. Also available is the ability to rewind through previous steering wheel actions. The steering wheel has more functionality than can be explored in this book. You should review the help topics for more information (click the steering wheel and then press F1).

Navigation Tools Tutorial

You can find a video tutorial exploring the navigation tools built right into Inventor. To view this video tutorial, select the Get Started tab and click the Overview button in the Videos And Tutorials panel. Then click the View Navigation button.

The Ribbon Menu

The Ribbon menu is composed of tabs and panels and is similar