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FreeCAD: Extruding a cross-sectional shape along the curve (Sweep)

FreeCAD 0.19

In this example, we explain how to create a solid by extruding a cross-sectional shape along the curve. Following shapes can be created by this method.

Bend
Spiral
Branches

  1. Start FreeCAD and create new documentNew document icon.

  2. Select Sketcher workbenchSketcher workbench.

  3. First we create a curve. This curve is used as pathway of extruding.

    1. Create new sketch planeSketcher_NewSketch on XY-plane.

      Create Sketch Plane-XY
      Creates sketch plane

    2. Select polylineSketcher_Line and draw sketch as follow. In polyline mode, you can draw arc with keybord M key. And exit polyline mode with mouse right click.

      Sketch 1

    3. Match the endpoints of the sketch to the sketch plane origin with point-on-point constraintConstraint_PointOnPoint. After that, click Close at Tasks tab in Combo View to exit sketch editing mode.

      Sketch 2

  4. Next we create cross-sectional shape to be extruded.

    1. Select the document in Tree View and create new sketch planeSketcher_NewSketch on YZ-plane.

      Create Sketch Plane-YZ
      Creates sketch plane

    2. Create a circleSketcher_CreateCircle as shown in following figure. You can set positions in rough because these will be adjusts in the restraint operation.

      Sketch 3

    3. Match the center of the circle to the sketch plane origin with point-on-point constraintConstraint_PointOnPoint. After that, click Close at Tasks tab in Combo View to exit sketch editing mode.

      Sketch 4

  5. Following figure shows the two sketches that has been created above steps.

    Sketch 5

  6. Select Part workbenchPart workbench. In the workbench, Select SweepPart_Sweep.

  7. At first, select a cross-sectional shape (Sketch001) and click ⇨ to set the cross-sectional shape as sweep-target.

    Sweep Task

  8. Then click Sweep Path and select a pathway of extruding in 3D View. If you want to select more than one line, select lines with pressing Ctrl key. Click Done to finish selecting.

    Sketch 6

  9. After selecting the pathway, check Create solid at bottom left of the dialog and click OK on Sweep dialog to create a solid by sweeping.

    Result

Any cross-sectional shape can be extruded along the curve with this sweep method. In following figure, a regular pentagon has been extruded along with a spiral that has been created with Creating primitivesPart_CreatePrimitives in Part workbench.

Spiral

You can sweep while changing the cross-sectional shape (It is usualy called "Sweep Blend") by using multiple cross-sectional shapes.

Sweeping-Blend1
Sweeping-Blend2

If a pathway of extruding has branching, the pathway cannot be extruded one sweep operation. So sweep each pathway and connect the two solids by a boolean operationPart_Fuse.

Branches

References