How to Create Ribbed Supports in FreeCAD

Ribbed supports, or gussets, provide structural stiffness to brackets without significantly increasing material weight. In FreeCAD, adding a rib involves defining a 2D profile on an intersecting plane and using the dedicated Rib tool within the Part Design workbench. This guide walks through the exact steps required to sketch, project, and generate a clean ribbed support structure on an existing L-bracket model.

Step 1: Open the Part Design Workbench and Select the Active Body

  1. Open your bracket model in FreeCAD.
  2. Ensure you are in the Part Design workbench.
  3. In the Model tree, ensure the Body containing the bracket is active (highlighted in bold). If not, double-click the Body to activate it.

Step 2: Establish the Sketch Plane

A rib typically sits perpendicular to the inner corners of the bracket, often running down the center.

  1. If the bracket is centered on the origin, select the origin plane that bisects the bracket (e.g., the XZ_Plane or YZ_Plane).
  2. If your bracket is not centered on an origin plane, create a Datum Plane:
    • Select a flat face parallel to the desired rib location.
    • Click Create a new datum plane.
    • Adjust the offset distance until the datum plane aligns with the center of the bracket where the rib will be positioned.
  3. With the plane selected, click Create a new sketch.

Step 3: Draw the Rib Profile

The Part Design Rib tool requires only an open single line or an open polyline that connects the two faces being reinforced.

  1. Click Create an external geometry reference (the icon showing a cube edge highlighted).
  2. Click the two internal edges or surfaces of the bracket where the rib will attach. This creates reference lines that allow your sketch to snap directly to the model.
  3. Select the Create a line tool.
  4. Draw a single diagonal line connecting the two reference features.
  5. Apply dimensions, such as the distance from the internal corner to the line endpoints, or specify an angle and a single length to fully constrain the sketch.
  6. Click Close to exit the Sketcher.

Step 4: Apply the Rib Feature

  1. With the newly created sketch selected in the tree view, click the Rib tool (represented by a profile between two perpendicular walls).
  2. In the Rib parameters panel on the left:
    • Thickness: Enter the desired thickness of the rib.
    • Midplane: Check this box if you want the thickness distributed evenly on both sides of the sketch plane.
    • Direction: If the rib generates outward or fails to form, toggle the Reverse Direction option to ensure it extrudes inward toward the bracket geometry.
  3. Click OK to generate the solid rib. FreeCAD will automatically extend the open line profile until it meets the solid walls of the bracket.

Step 5: Duplicate for Multiple Ribs (Optional)

If your bracket requires multiple evenly spaced ribs:

  1. Select the completed Rib feature in the tree view.
  2. Click the Linear Pattern tool.
  3. Select the direction axis perpendicular to the rib plane.
  4. Set the Length and the Occurrences count to distribute identical ribs across the width of the bracket.
  5. Click OK to apply the pattern.