Generative Shape Design Copyright DASSAULT SYSTEMES 2002 1
Exercise 60 min. The Knob In this exercise you will have the opportunity to model an appliance Knob starting from an empty model. You will create the supporting Wireframe and build the base surfaces for a quarter section of the Knob. Next, you will trim, fillet, and perform symmetry operations on these surfaces to obtain the complete Knob. You will then perform a Draft analysis on the surfaces to determine if the Knob can be extracted from a mould. In order to obtain a 4 Degree draft, you will modify a supporting line segment and will see the automatic propagation of this change through to the final Skin. Finally, you will see how to work in a Hybrid environment by creating a Solid by offsetting the Skin. A completed model Knob_Completed.CATPart is available for reference. Copyright DASSAULT SYSTEMES 2002 2
Design Intent: The Knob R=5 mm. Fillet all around Fillet varying from R=20 mm. to R= 10 mm. 4 Degrees Draft (Inside and Outside) 4 mm. Thickness Copyright DASSAULT SYSTEMES 2002 3
Design Process: The Knob 1 Generating the Wireframe 2 Extruding basic surfaces 3 Performing operations : Trim, fillets, and symmetry 4 Offset a solid Copyright DASSAULT SYSTEMES 2002 4
Exercise 10 min. The Knob (Step 1): Generating the Wireframe In this step you will sketch and constrain the wireframe geometry that will support the surface. Copyright DASSAULT SYSTEMES 2002 5
Do It Yourself (1/3) Using the ZX Plane as Support, draw on the fly a quarter circle with R=64 mm, centered on the origin ; as shown. Rem. : Do not use the sketcher. Use the stacking commands functionality Load: Knob_Step1_start.CATPart Copyright DASSAULT SYSTEMES 2002 6
Do It Yourself (2/3) Using the YZ Plane as Support, draw the highlighted arc on the right at the position shown. Rem. : Do not use the sketcher. Use the stacking commands functionality Copyright DASSAULT SYSTEMES 2002 7
Do It Yourself (3/3) Using the YZ Plane, Sketch the line on the right and set all the Constraints as shown. Save your Part. Call it Knob_Step1 Copyright DASSAULT SYSTEMES 2002 8
Exercise 10 min. The Knob (Step 2): Extruding Basic Surfaces In this step you will create the basic surfaces for the Knob. Copyright DASSAULT SYSTEMES 2002 9
Do It Yourself Extrude the two arcs by 70 mm and revolve the line by 90 Degrees. Save your part. Name it Knob_Step2. Load: Knob_Step2.CATPart Copyright DASSAULT SYSTEMES 2002 10
Exercise 20 min. The Knob (Step 3): Performing operations In this step you will perform the following operations on the Knob: Trim Split Extrapolate Variable Fillet Edge Fillet Symmetry Join Copyright DASSAULT SYSTEMES 2002 11
Do It Yourself (1/4) Trim the first Extrusion with the Revolution. Split the second Extrusion with the Trim. Load: Knob_Step3.CATPart Copyright DASSAULT SYSTEMES 2002 12
Do It Yourself (2/4) Extrapolate the Split Up to Element - specify the Trim. Use the Assemble Result option. Extrapolate the Extrapolation Up to Element - specify the Trim. Use the Assemble Result option. Trim this second Extrapolation with the first Trim. Copyright DASSAULT SYSTEMES 2002 13
Do It Yourself (3/4) Rotate the part around. Put in a fillet varying from 20 mm. on the left to 10 mm. on the right. Apply a R = 5 mm constant EdgeFillet on the edges shown below. Copyright DASSAULT SYSTEMES 2002 14
Do It Yourself (4/4) Perform a Symmetry on the resulting EdgeFillet. Now, Join the two symmetrical parts. Perform a Symmetry on the Join and once again, Join the two symmetrical parts. Save your part as Knob_Step3. Copyright DASSAULT SYSTEMES 2002 15
Exercise 10 min. The Knob (Step 5): Offsetting a Solid In this step you will see how surfaces are useful for creating complex solids. In this exercise you will specify an offset on the final surface to obtain a solid with a specific wall thickness. Copyright DASSAULT SYSTEMES 2002 16
Do It Yourself (1/2) Change to the Part Design Workbench. Select the final join and create a 4mm Thicksurface pointing inward. No-Show the open body to see only the solid. Switch the render style to wireframe mode and look normal to the YZ plane. Notice that the offset of the 4 mm Degree drafted wall has resulted in a nonhorizontal footprint for the knob. Load: Knob_Step5.CATPart Copyright DASSAULT SYSTEMES 2002 17
Do It Yourself (2/2) Perform a Split on the solid using the XY plane to take off the excess. Add a material Rubber and switch to the Customize Render Style. Reference model : Knob_End.CATPart Copyright DASSAULT SYSTEMES 2002 18