Discover the importance of parametric design and T-spline model bodies in effectively designing a lampshade. Learn how to use an as built joint, modify user parameters and understand how parameters of objects can influence the overall model design.
Key Insights
- The article explains how to assemble as built joints, select bodies, and create rigid joints within the design of a lampshade. The modification of user parameters is also discussed.
- In the context of T-spline model bodies and parametric design, the article describes how changes in user parameters can impact the positioning of components within the overall design. For example, a lampshade washer may drop inside, and a lampshade may appear to have slid further away from a lampshade arm.
- The article emphasizes the importance of placing a joint origin and then a rigid joint instead of an as built joint to attach components together. This ensures that all parts move together when user parameters are updated, contributing to a more accurate and cohesive design.
This lesson is a preview from our Fusion Certification Course Online (includes software & exam). Enroll in a course for detailed lessons, live instructor support, and project-based training.
Before we finish our lampshade, I would like to talk a little bit more about parametric design and our T-spline model body. We can see that right now, we modeled our body in place, so we can still move it around, meaning it's not joined.
I know that I could go to Assemble > As-Built Joint, select this body and my washer with a rigid joint, and click OK. This seems to be right because as I move my lampshade arm around, all of my components move with it. However, let's see what happens when we update our user parameters.
I will go to Modify > Change Parameters, and change my thickness to 10. Let’s see what kind of changes we've made. We can see that right away, our lampshade washer has dropped inside, and our lampshade appears to have slid further away from our lampshade arm.
What actually happened is that when our lampshade arm and the entire assembly updated, the as-built joint did not maintain the relative position. The As-Built Joint did not specify a fixed position for either of the objects, so when the user parameter updated, the lampshade had no reason to move accordingly. I will Undo, and instead place a joint origin and a rigid joint—not an as-built joint—to attach our lampshade and rubber washer.
First, I will go to Assemble > Joint Origin. You can see that as I hover over my lampshade, I cannot snap to exact locations anywhere on the model. T-spline objects and surfaces do not allow you to place points anywhere—only at specific locations. We can see a line running vertically along the side of the lampshade, representing the start and end of the revolve.
Learn CAD
- Nationally accredited
- Create your own portfolio
- Free student software
- Learn at your convenience
- Authorized Autodesk training center
I can place my joint origin anywhere along this line or around the outside edge—it will snap to specific points. I will hold CTRL, and you’ll see that I can snap to the bottom edge, midpoint, and top edge. I will hold CTRL and select the top edge, and zoom in to view the point more clearly.
After hiding my rubber washer, I can see that the joint origin has come in perpendicular to the top of the circle. I want to reorient this so that it lies flat. I will click Reorient and choose this surface. You will notice that we also have the option to define the X-axis direction.
I want to match the X-axis to the orientation in our model, so I will select this back edge to reorient my joint origin. Now I can drag in, and I know this is -15 millimeters because the original diameter of our cylinder was 30 millimeters. Moving it 15 places the joint origin in the center. I will press ENTER to place my joint origin.
I’ll click the light bulb to turn my rubber washer back on, and now we can place our joint. I’ll go to Joint, first select the joint origin we just created, then orbit the model to look at the bottom of the washer, and select this bottom edge—it will automatically snap to the center of the circle. We now have a rigid joint between those two objects.
I’ll click OK, and now let’s see what happens. I can move my components, and they are now properly constrained. Let’s test this by updating our user parameters. I’ll go to Modify > Change Parameters and update the thickness to 10 one more time.
This time, the joint is moving the model as expected when the parameters are updated. I can change both of these parameters as much as I’d like, and my lampshade and the rest of the model will update accordingly. I will return these values to 30 and 15, and click OK.
Let’s go ahead and save the file. I will right-click > Unisolate to show the rest of the lampshade components. I’ll go to the Home view, select these components, right-click > Create Group, and save the file one more time.
In the next video, we will finish the lampshade modeling.
I’ll see you in the next video.
