Day 27 of Learn Fusion 360 in 30 Days for Complete Beginners! – 2023 EDITION – Introduction to Autodesk Fusion’s T-spline Modeling Tools

T-splines Vase Demo File

Autodesk Fusion file: https://a360.co/45JedIh
Select the Fusion ‘share link‘ above > select the ‘Open in Fusion’ button > select ‘Open’ when prompted. This will open the demo file in your Autodesk Fusion application. Everything is set up and ready to use with the tutorial.

Key Terminology for T-spline Modeling in Autodesk Fusion

• T-spline: A type of surface representation that allows for smooth transitions and complex shapes, combining the benefits of NURBS and polygonal modeling.
• Control Points: Points that define the shape of a T-spline surface. Moving these points adjusts the surface.
• Edges: Lines connecting control points. Edges can be manipulated to change the surface.
• Faces: The flat surfaces bounded by edges. Faces can be subdivided or adjusted to refine the model.
• Vertices: Points where edges meet. Vertices can be moved to adjust the shape.
• Crease: A feature that sharpens an edge or vertex, making it less smooth.
• Extrude: Extending a face or edge to add geometry to the model.
• Bridge: Connecting two separate faces or edges with new geometry.
• Insert Edge: Adding new edges to an existing T-spline surface to refine the shape.
• Subdivide: Dividing a face or edge into smaller segments to increase detail.
• Symmetry: Creating mirrored changes on both sides of a model to ensure it remains balanced.
• Manipulators: Tools that allow you to move, rotate, or scale T-spline elements.
• Form Mode: The mode in Fusion 360 where T-spline editing occurs, allowing for freeform design.
• Box Mode: A visualization mode that displays the T-spline model as a low-resolution boxy shape, useful for seeing the underlying structure.
• Smooth Mode: A visualization mode that shows the T-spline model in its smooth, final form.
• Match Edge: A tool to align the edges of a T-spline model with other geometry or sketches.
• Pull: Adjusting control points to move closer or further from a reference surface or curve.
• Weld Vertices: Combining two or more vertices into one to simplify the model and create smoother transitions.

Transcript

Welcome to Day #27 of Learn Fusion 360 in thirty days!

Today you’ll experiment with T-splines. We’ll start with the basics, creating a simple 3D printable vase, and finish with a complex twisted version!

Fusion’s toolbar includes Solid, Surface, and Mesh modeling.

However, you may have noticed this purple icon in the toolbar. Selecting “Create Form” will place us in a Form contextual environment.

Form modeling is commonly known as T-spline modeling. T-splines are a technique used to create complex and organic shapes. They give us the ability to push, pull, stretch, and extrude the various faces and edges that make up the model.

Start by activating the Cylinder primitive.

We’ll select the XY origin plane to sketch on.

Select the origin point for the center of our cylinder and select again to set the circle. We can define the width of our cylinder in the dialog.

Along with design primitives, you can also start T-splines with Extrude, Sweep, Revolve, and Loft. When designing with T-splines, it’s important to start with a shape closest to the final design.

This first vase will be 75mm in width and 250mm in height.

We can then define the number of faces for both the diameter and height. “Faces” refer to the flat or curved surfaces that make up the T-spline model.

Each face is bounded by edges… and vertices.

Edges, faces, and vertices are how we manipulate the form. The key with T-spline modeling is to keep the number of faces relative to the shape of the design. Too many faces will make it too hard to manage, while too few faces may make it hard to achieve the curvature or desired shape.

Let’s set the diameter faces to 8 and the height faces to 6. This gives us a rough starting point for the sections we’ll use to shape the design.

Select OK to create the cylinder.

Notice we can now select individual faces, edges, and vertices.

Let’s select a face three rows up from the bottom.

While holding the Shift key we can double-click on the face next to it, which selects the entire row.

To manipulate the form we’ll typically start with the Edit Form tool in the toolbar, or from the right-click “Marking Menu.”

Notice the different icons that allow us to alter our selection in different directions.

The very center icon represents universal scaling. We can scale our selection by dragging this left or right.

I’ll view this from the Front and drag the scaling icon to increase the scale.

I’m not liking the look of this so far. One of the great things about T-spline modeling is that we can select undo or CMD + Z and quickly experiment with a different selection.

Instead, I’ll double-click on the edge below the third row. Double-clicking selects the edge all the way around. Let’s scale this selection.

Notice this gives us a completely different result.

Perhaps we want to make the stem of the vase narrower. Let’s double-click on the very top edge to select the entire edge.

If we tried scaling this, it would only make the very top narrower. So I’ll undo that and let’s also double-click the second and third edges as well, while holding the Shift key. Holding the shift key lets us add more than one selection.

We’re now scaling everything together which results in a smooth and narrow contour.

Let’s also make the stem taller.

We’ll select only the top edge and pull up with the single directional arrow.

Notice how this physically stretches the faces and makes them larger.

If we undo that, we can also hold down the Option key on Mac, or the Alt key on Windows… which performs an Extrude along with the directional pull.

Notice this extrudes an additional row of faces, providing us with more control if desired. We could release the mouse and repeat the process to continue adding faces, when needed.

Perhaps we later decide we don’t need those extra faces. Without the Edit Form tool active, we can click and drag to perform a window selection over them. Press the Delete key to remove them.

Let’s select the top edge of the vase and increase the scale a little bit. This completes the first vase design!

In just a matter of minutes, we were able to create this curved organic shape using T-splines. Something that would’ve required more sketches and time with solid or surface modeling.

When the design is complete, we’ll need to select “Finish Form” in the toolbar. This will convert the design to a surface body if not fully closed or a solid body when fully closed.

To make this 3D printable, we’ll later look at how to apply a bottom and a desired wall thickness.

Let’s start the more complex twisted vase. Open the provided demo file which includes a sketch with a side profile of the vase.

After entering the Form environment, this time we’ll use the Form Revolve tool.

Selecting our outer spline as the Profile and our centerline as the Axis.

Most of our changes will be in the vertical direction, so let’s set the number of horizontal faces to 4. This is the fewest amount without altering our contour, and we can always add more later.

We’ll set the number of vertical faces to 20.

Lastly, we want to turn on Symmetry.

Symmetry will allow us to edit a single edge or face and the rest of them will update, keeping the object symmetrical.

These green lines let us know that we have symmetry. We can double-click one of the edges to select the entire row, and notice everything turns yellow.

Yellow informs us that items with symmetry are selected.

To create our twisted shape we need to have small faces that we can pull away from the center axis. 

To do this, we’ll right-click and select “insert edge.”

This is going to let us add a new edge line. Let’s set the distance to 0.1, which represents 10% of the distance between the selected edge and the next edge.

After selecting OK, you’ll find the edge is inserted all the way around because of our symmetry. 

Let’s double-click to select the entire edge again. This time we’ll use the Crease tool from the modify menu. This turns our smooth surface into a sharp connection.

Notice the edges now have a sharp connection and our vase is no longer smooth.

We’re going to pull this edge out further, creating the ribbed shape around the model.

Double-click to select an edge and we’ll use the Edit Form tool.

Our single-directional arrow may not be parallel to the selected edge. This can be problematic since we don’t want the faces to overlap and we want to pull away from the center axis.

In the Edit Form dialog, we can change our Coordinate Space from the World Space to the Selection Space. Notice how the arrow is now parallel to the edge.

This will allow us to drag the arrow to create the sharp edge that we’re looking for.

Let’s type out -7mm for the distance.

We’re now ready to give the twisted look to the model.

Before we start twisting the model we’ll need to turn off the symmetry. We’ll use “Clear Symmetry” and select the model. Notice the green lines disappear and the symmetry is now turned off.

Looking at the model from the Front view, we’ll do a window selection over the top three rows.

Using Edit Form, we’ll have to look at this from a perspective so we can drag the correct angle slider to start twisting the vase. Let’s make the first twist 45 degrees, and for each one, we’ll use 10 degrees less.

We can keep “Edit Form” active and select the top two rows. Make sure to do this while looking at the Front view so we don’t select any other faces.

We’ll make this 35 degrees and then repeat the process for the top row, making it 25 degrees.

We now have a relatively complex twisted vase created with a few simple steps using T-splines. This can be a lot of fun to experiment with! Just make sure faces don’t intersect with each other. If faces intersect, the model will not convert when selecting “Finish Form” in the toolbar.

We’ll end up with a surface body once again, so let’s look at how to prepare both of these vase designs for 3D printing.

Firstly, if we zoom in on the top or bottom, you’ll notice it’s no longer flat because we twisted the shape. We’ll want to fix this by slicing the surface body.

Let’s create an Offset construction plane. Make it 1mm from the origin plane, ensuring we cut enough away from the bottom.

Repeat the Offset plane, making this 270mm from the origin plane.

With Split Body, we’ll select our surface body as the “Body to Split,” and then both construction planes as the splitting tools. I recommend selecting these in the Browser so we know we don’t select the origin plane by accident.

After splitting, we’ll have three surface bodies in the Browser. Let’s rename the main vase one that we need to keep.

We can then right-click on the other two, selecting Remove to remove them. Remove is parametric and recorded in our timeline, allowing us to undo the action if needed.

We discussed some of Fusion’s surface modeling tools on day #25.

When working with T-splines you’ll find that many workflows require you to finish with surface modeling.

In our case, we’ll use the Patch command to close off the bottom of the vase.

Select the bottom contour, which results in a new surface body.

We can then use Stitch to combine all of these surface bodies, resulting in a single surface body.

With Thicken, we can define a desired thickness to the surface model, such as 2mm.

As an alternative, we could delete the Thicken command in our timeline. 

Let’s double-click to edit the Patch command and select the top of our vase as well.

We can then edit our Stitch, fully enclosing the volume, which turns this into a solid 3D body. This would allow us to use the Shell command to hollow out the body. 

For different effects, you can also apply Chamfers or Fillets to the creased edges.

If you plan to 3D print this, try the Vase mode in Bambu Studio, or your chosen slicer. Vase mode prints only a single wall without any infill, reducing the print time and filament.

In Bambu studio, this is found in the “Others” tab.

Under the “Special Mode” heading, check the option called “spiral vase.”

I’ll see you on Day #28 where we’ll take an introductory look at Autodesk Fusion’s Render Workspace.