Create curves-on-surface a certain offset distance from a surface curve

1. Chose Surfaces > Rolled Edge > Tubular Offset .
2. Set Surface to None in the option box.
3. Click the first curve to offset from. This can be a curve-on-surface, an isoparm, or an edge.
   

   A blue radius manipulator appears at the beginning of the curve.

4. Do any of the following:
   • Pick another curve to add on to the tube. You can use any curve as long as is has positional continuity with the current curve.
   • Click the blue circle, and either drag to change the radius of the tube, or type a radius value and press (Windows) or (Mac).
   • Click anywhere on the selected curve(s) to add another radius manipulator. This allows you to create a variable-radius tube.
5. Press the Recalc button.
   
6. Repeat steps 4 and 5 as needed.

This tool maintains construction history. When you reshape the centerline curves, the offset curves-on-surface are automatically recreated.

If Surface Type is set to Multiple surfaces, the offset curves-on-surface are segmented to correspond to the multiple tube surface boundaries. (When Bezier Surfaces is off, these also correspond to the input curves-on-surface, or surface edges.) To create the offset curves-on-surface as a single piece (for each surface), you must set Surface Type to Single surface.

Create curves-on-surface offset on more than one surface at once

If two surfaces share an edge, you can build curves-on-surface, grooves, or tubes on both surfaces with the Tubular Offset tool.

The tubular offset is built from the selected edge of the primary surface (first surface you select). The secondary surfaces are trimmed or have curves-on-surface created on them by the tubular offset.

1. Choose Surfaces > Rolled Edge > Tubular Offset.
2. Click on the edge (isoparm or curve-on-surface) of the primary surface. You can use the Chain Select option to select all edges tangent continuous with it.

   The Pick Chooser window appears if the selected edge intersects with other geometry.

3. Select the primary surface through the Pick Chooser.

   The surface turns pink to indicate that it’s selected. The edge of the surface turns yellow showing the path of the tubular offset.

4. Select one or more positionally (G0) continuous surface edges that overlap the edge of the primary surface. Hold the key to select them through the pick chooser.

   The secondary surfaces turn pink.

5. Click the Recalc button in the bottom right corner of the window.

   The tubular offset is built on all selected surfaces.

   The manipulator behaves in exactly the same way as in the previous workflow.