FreeCAD Tutorial 1b: Design of an Electronic Box, Continued

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Link to: Tutorial 1a (prev)

Link to: Tutorial 1c (next)

Introduction

This tutorial is the second in a series teaching basic CAD sketching and modeling tools using the open-source package FreeCAD.

In the previous tutorial, we designed a simple hollow box. In this tutorial we will start to add the features that will give it its function: A sample electronics enclosure that could be made on a 3D printer.

In this page we will explore more aspects of sketching, especially those that add features to the surfaces of a simple model, and the addition of geometric relations between features so that changes to the model's dimensions will carry through more smoothly.

The pace of this tutorial will be somewhat faster than the previous one because knowledge of tools already presented will be assumed.

Add Mounting Lugs

The box will need to be mounted to a surface, so the first feature we will add will be a pair of mounting lugs on the bottom of the box.

We will use a slightly inefficient process for designing them in order to examine some of the tools for adding dimensional constraints to features in the design. As you get more experience, hopefully some of the easier ways to design these features will become evident.

Open a New Sketch on the Bottom Surface

With the box displayed as it was at the end of the previous tutorial, rotate the view so the box bottom is visible. To do this, use the () orientation icon in the upper-right corner of the window.

Click on the box bottom to select the plane, and hit the () sketch icon to open a new sketch.

If you are unfamiliar with this operation, please review the previous tutorial.

To prepare the sketch for input, you will need to incorporate some geometric elements from the existing part. Click on the () "External Geometry" selection tool and use it to select the two vertical edges on the left and right sides of the box bottom. The two endpoints should appear in bright red.

References to these lines should appear in the "Elements" list of the sketch, listed as "External."

Select the () and choose the "Centered Rectangle" option.