Top-Down Modeling in Solidworks

David Schoon dave@bostondevice.com

What is Top-Down Modeling? A method of driving multiple part designs using a single “parent” part

Parent Part sketches, surfaces, solids

Child Parts Driven features from Parent Part

Why Use Top-Down Design? •  Maintains key relationships between parts

–  Clearance and interface design details –  Proper positioning in assemblies

•  Rapid modifications –  One change to master part can propagate to multiple

derived parts

•  Multi-User assemblies –  Can be used to define interfaces in between

subassemblies –  Avoids circular references within assemblies

Parent Sketching | Front Profile •  Start new part •  Sketch on front plane •  Use “symmetric” and “equal”

constraints •  Add dimensions •  Close sketch and save part

Parent Sketching | Main Cross-Section •  Create new sketch on “top” plane •  Sketch middle profile (below) •  Constrain middle profile to Front

Profile •  Sketch top and bottom profiles •  Add dimensions •  Close sketch and save part

Parent Sketching | Front Details •  Create new sketch on Front

Plane •  Draw LCD, button, speaker

and camera outlines •  Close sketch and save part

Embed Parent into Child Parts •  Insert > Part

–  Find the “parent” part that you saved and allow part to drop to default location.

•  Save Front Part –  You will now have all

of the base geometry of the parent part to build from in your Front Part.

•  Repeat for Base Part & Middle Part

Build Front Part Features •  Create reference plane coincident with

upper line in cross-section sketch •  Create new sketch on reference

plane, and “convert entities” of main front perimeter profile

–  Make “converted entities” construction geometry

•  Offset converted entities (select chain), and delete dimension afterward

•  Constrain offset profile to appropriate vertex on cross-section view

•  Complete similar process for cut on underside

•  Use split-line curves to define LCD, button, speaker and camera profiles

Ribbon & Base Features •  Complete similar processes

for metal ribbon and base features

•  Cross-sections of parts should be identical to cross-section sketch in master

•  Use sketch constraints whenever possible (and minimize dimensions)

Assemble Parts •  Create new assembly •  Drag parts to default coordinate

system –  Parts should automatically be

placed properly •  Check cross-section to

ensure clearances are consistent with parent part

•  Other things to try: –  What happens when you

change the dimensions in the parent model?

–  How would you break out the button part?