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#1 2014-08-08 13:24:49

Odysseus
n10b
Registered: 2014-07-08
Posts: 23

FreeCAD - Tutorial 1 - Basic Concepts

I guess CAD can be a little bit intimidating when you are using it for the first time and maybe you don't know where to start.
However, in the emerging world of 3D printing, this is an essential skill any hobbyist should have. My objective is not to provide you with a detail explanation of every feature of FreeCAD.

One more time, I am not an expert of this software. My objective is to document my learning process as well as to give you enough details to get you started in what seems to be the most logical way to start learning FreeCAD since its workflow seems to be very similar to CATIA.

Part versus Assembly

First, some essential vocabulary:

  • sketch: this is a 2D design

  • part: this is a 3D design of a real world object

  • assembly: many parts together

  • draft: a 2D view of a part or assembly

The difference between a part and an assembly is not always clear and depends on your design.

Let's take an example:

A tire and its wheel can be designed as two different parts or as a simple one. It really depends on the level of details and flexibility you need in your design. However, if you go with 2 parts, you will be interested to have both wheel and tire defined as a single entity: this is an assembly. An assembly is defined as a bunch of parts with relative positioning. Positioning can be handled by the CAD itself or by a higher level software called PDM (Product Data Manager) or PLM (Product Lifecycle Manager). Once your got you tire+wheel assembly, you can reuse it as many time as you want to create, for instance, 4 wheels in a mobile robot. The concept is really similar to code reuse; once you have a generic piece of code, you can create a library. Having a separate wheel and tire under a single assembly rather than having them together inside a single part can have advantages since you may want to try different brands of tires coming from some kind of FreeCAD tire library. When you split your design, you can also consider see many designers in a single company work on the same design.

Workbench

The second concept I should talk about is workbench. A workbench is the equivalent to a bunch of features depending on what you want to achieve. For a commercial CAD software, a workbench comes with a licence and a cost. Some generic workbench like part design for instance will be less expensive than FEM workbench for instance. The good thing with FreeCAD is that you can have all those workbenches for free!

I have installed the best so far version of FreeCAD, which is 0.14 at the time I am writing this tutorial on Ubuntu. I may say that starting FreeCAD is a bit weird. It opens a grey window with a few menus. You have to manually select Workbench menu under View menu. There is no default workbench selected.

I would suggest that you go on submenu "Preferences..." under the General tab of "Edit" menu and on the "Start up" section select a default workbench to auto load. Take "Part Design" workbench.

Close FreeCAD and start it again!

Next tutorial: First Part Design

Last edited by Odysseus (2014-08-08 18:11:34)

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