Fillets

Let's imagine you have two NURBS surfaces representing a body and a handle of a coffee cup and you would like to blend the handle to the body seamlessly. The fillet tool can be used for this.

Let's try this.

1. Use the rotation tool to create a body of a coffee cup. Use the Sweep tool to construct the handle. Position the handle to its correct position, as shown by the image below:

Two meshes for blending

Note: make sure both ends of the handle point towards the body of the cup.
 

2. Select the body and the handle (in this order) and click the Fillet tool. You can now see the fillet surfaces created between the body and the handle. As usual, the control bar shows you fillet specific options, such as the radius. Specify the desired radius and click 'Accept'.

The handle blended with the body

You can now move the handle (or the cup) and the shape of the created blending surfaces is updated. The handle will remain seamlessly blended with the cup.

Tutorial project: 'tutorprojects\modeling\nurbs\fillet\cup_handle_fillet'
 

The fillet tool can determine the shape for the blending surface by 'extrapolating' the second selected object (the handle). The following example demonstrates this.

1. Create a 4x4 rectangular mesh. Then use the rotate tool to create a cone. Place the open end of the cone near the planar mesh as shown below:

A cone and a planar mesh

2. Select the mesh and the cone and activate the Fillet tool. Click 'Accept'.

The created surface is tangential with both the cone and the planar mesh.

Tutorial project: 'tutorprojects\modeling\nurbs\cone_mesh_fillet'

Note: If the cone is too big in relation to the planar mesh, the fillet tool may not be able to connect it to the planar mesh.
 

A tube with a lid

The fillet tool can also be used for creating a lid for the ends of a closed profile tube surface.

1. Create a closed profile curve and use the sweep tool to create a tube. Then create a planar surface, which will be used as a lid for the tube.

A planar surface and a tube
 

2. Select the planar mesh and the tube and activate the Fillet tool. Set the Trim option to 'Trim curves' And this time specify a negative Radius. This makes the created surface bend inside rather than outside. Accept the tool.

3. Select the trim curve created inside the planar mesh object. The control bar now shows you the trim curve specific tools. The 'Invert' option is set for the trimcurve. Uncheck the 'Invert' tool to invert the trim curve .

A sweep surface blended to a planar mesh with a negative radius
 
Tutorial project: 'tutorprojects\modeling\nurbs\fillet\tube with lid'