5 Common Problems for New Inventor Users 

If you’re sitting at your desk with your head propped in your hands, sighing deeply while staring at your computer screen where Inventor is poised to taunt you yet again, take heart. Maybe you’re like a lot of new Inventor users, and you decided to teach yourself to use it. After all, you’ve read the blogs and online opinions that say it’s “easy to use.” You’ve read some Autodesk Knowledge Network articles and watched a few YouTube videos. How hard could it be? Hey, 80% of using a new software package is just paying attention to the subtle things that can make it useful and frustrating at the same time (and, yes, I made that statistic up using the 80-20 rule). But in the 19 years since Inventor’s first release, some things have definitely risen to the top as common problems:

1.) Understanding Project Files

One of the first things you should do when you embark on a new project is set up a new project file using the Project Wizard. If you don’t set up your own project, Inventor will do it for you and name it “default.” This is fine for investigating or experimenting, but for a real-world project like adults work on, take the time to set it up right. This may elicit a “DUH” from you, but it happens. The project (ipj) file is where your design data will be stored so everything interacts properly. Project Wizard sets project type, number of versions you want to retain when saving, folder where you will edit files on your computer, and content center configuration settings.

• • Project type
  • Number of versions you want to retain when saving
  • Folder where you will edit files on your computer
  • Content Center configuration settings

Your “active” project is the one you are currently working on. The system knows where to search for data on that project. If you’re working on multiple projects and activate another one, the system changes the file access dialog boxes and the location where it searches for data. Pay attention when you open and save files, so you’re working in the correct project. I know, another “DUH” moment, but if you get it wrong, you’ll be pounding your head on your desk and screaming, “WHY?!”

2.) Fully Constraining Sketches

It’s important to fully constrain your sketches. When a rendering of a designed part is not functioning correctly, it’s usually not properly constrained – basically meaning it’s missing dimensions. Fortunately, Inventor will automatically tell you the number of constraints required to set all the necessary dimensions in your design. Using the Auto Dimension dialog box, you can use your left mouse button and drag a selection window around your sketch, then click to select. When your design is “Fully Constrained,” Inventor even tells you so at the bottom of your screen. Sometimes it’s the small victories that make a person’s day.

3.) Unintended relationships between features

In Inventor, feature relationships are the result of a dependency. The independent feature is referred to as the “parent,” and the dependent feature is called the “child.” Be sure you know the dependencies between features before you edit or delete them. You can check relationships between features and change them by right-clicking on a feature to see its relationships. In the Relationships window, you can see the parents and children of that feature and use the Edit feature to change the relationships if they are not what you intended.

4.) Bottom-Up vs. Top-Down Design

Sometimes designs use standard components, and sometimes they require new parts. Designing new components can be fun, or it can be another head slammer.

• • For bottom-up part design, Inventor users start with existing parts and sub-assemblies and put them into an assembly file. Constraints are then added to mate the components and align them. If components don’t exactly fit, the Context command can be used to edit the components and resize them.

• For top-down part design, Inventor users start with design criteria and create the components that are needed. This involves engineering and uses 3D part modeling to develop a design that’s essentially driven by a unique part. The final assembly will be a collection of parts designed specifically for this project.
• Most assembly modeling involves a little of both bottom-up and top-down design, referred to by Autodesk as “middle-out.” (So clever, but it reminds me of middle-age-spread, which is to be avoided.) As the assembly design is developed, existing components are added or new ones are created in place.

5.) Constraints vs. Joints

Inventor Constraints and Joints both create relationships that set a part’s placement and movement. It typically takes fewer joints to achieve the same results as using constraints. Joints and Constraints can be used together for better results.

• Constraints eliminate degrees of freedom (DOF) and are simpler, thus more popular, to use than Joints. Each component has six DOF: three moving along the X, Y, and Z axes (translational) and three rotating around them (rotational). Extra DOFs are common when using constraints. When you apply a constraint (adding relationships), like mating two components in an assembly, one (or more) DOF is removed.
• Joints define the part’s motion. They achieve this with less input and fewer relationships. A single joint can replace multiple mate constraints. Joint settings can be “locked” to eliminate freedom; if also “protected,” Inventor will notify you when changes in the drawing will violate the part’s required motion. Lock and Protect are found in the context menu when you select a connection. Unlike locking, which allows the part to change location when partner components move, “grounding” (available in the Browser Context menu) fixes a component’s position in the workspace. It’s an Inventor best practice to ground at least one component to provide an anchor for all other components.