Top-down Design Using Derived Sketches
Top Down Design Using Derived Sketches: A Parametric 4-drawer Cabinet Example.
Step 1: Create the Control Part
Create sketches with dimensions defining the cabinet, the drawers, and the cut-outs for the drawers in the cabinet case. Link your dimensions to variables in the Equations list & save this as your control part. Also define a Plane offset from the front plane that controls the depth of the cabinet.
Step 2: Create the Assembly
Create an assembly and insert your control part as the first part in the assembly. Create 5 empty parts with names for the cabinet case, and one part for each of the 4 drawers and insert those into the assembly by just checking okay when prompting for position (i.e., all parts are constrained so their Front, Right, and Top planes are constrained to the Top, Front, & Right Planes of the Assembly.) These parts are empty parts with no sketches or any geometry at this point.
Step 3: Insert Derived Sketches
- Edit in place the cabinet case in the assembly. Select the cabinet case sketch in the Control Part and then Ctrl select the front plane in the Cabinet Case part that is being edited. With those two items selected, now Insert a Derived Sketch (In the Insert Pull-down menu), locate the derived sketch and constrain its orientation by constraining the center at the origin, and one of the corners to the original Control Part sketch.
Step 4: Create the Cabinet Base
Use the derived sketch to extrude the profile of the Cabinet base back to a plane defined in the Control Part.
- Shell the cabinet (maybe 0.5 inch thick) without removing any of the faces.
- With the Cabinet Base part still being edited, derive the top drawer cutout sketch on the front plane. Constrain the origin and the orientation of the drawer cut-out sketch in a similar way that the Cabinet base sketch was constrained.
- Use this derived sketch to cut out the space for the top drawer but using Extrude Cut, Up Until Next option.
- Repeat steps 3 and 4 for each of the 3 drawers.1
- Maybe you will want to add an appearance such as a wood texture to the Cabinet Base. Now, exit the editing of the Cabinet base.
Step 5: Create the Drawers
1- Now, repeat the steps in creating the cut-outs, except let's do an offset to give a little clearance between the Cabinet cut-outs and the drawers.
2- So, while still in the assembly, edit the top drawer and select the Front Plane. Expand the Control Part and Control Select the sketch of the Top Drawer.
3- Insert a derived sketch onto the Front Plane of the top drawer and constrain it like we have constrained the location and orientation of the previous derived sketches.
4- Start a new sketch on the Front Plane, and sketch an offset from the derived sketch created in step 3 above.
5- Extrude this sketch Offset from Surface (maybe 1" clearance for .5 clearance from the .5 thick Cabinet base part) from the Back Plane of the Cabinet back Plane that is controlled in the the Control Part.
6- Shell this drawer removing the top and front faces.
7-Create the Face of the top drawer. While still editing the top drawer part, Select the Front Plane of the top drawer and Control Select the Face Control Sketch in the Control Part file.
8- Insert a Derived Sketch of the Face for the top drawer.
9- Extrude this sketch frontwards maybe .5" or .75" and merge with the top drawer.
10- Assign an appearance to the top drawer.
Step 6: Create the other drawers.
- Repeat the steps 2 thru 10 in Step 5 above for the other 3 drawers.
- Add a Top Plate using the same technique of derived sketches to make sure it updates with the size of the overall Cabinet.
- Add champers and other features to the drawers and the Top Plate.
Step 7: Export the Variables in the Equations list
- Under Tools, Equations, Export the Variables in the Control Part file.
- Link the Variables to this exported text file.
- Edit this file using Notepad and change the Cabinet dimensions.
- Alternatively, write a VB Macro to edit the text file for a better user-interface of changing the variables.
- I will upload my Parametric Cabinet with the integrated VB Macro in my Models in GrabCAD.
- I also have a brief YouTube Video that reviews all these steps:
Step 8: Make a final design Independent of Control Part
- Once you have the size of a Cabinet you like, you could now use the Top-Down design approach proposed in the SolidWorks tutorials such as Split Part or Insert Part to create the individual boards or panels for each of the parts for each drawer and the Cabinet base.