Program-Independent > Mechanical

CAD 101: The Basics

Contributors:

Nate Gorton

Introduction

Hello and welcome to your first CAD lesson! In this article you will learn the very basics of CAD with OnShape, no previous experience or knowledge is required to follow this article. This article is here to give you that experience and knowledge. This article also isn't here to teach you how to CAD robots, but the skills you learn here will prove very useful in CADing robots. So without further ado, let us begin.

Introduction

Section 1 | What is CAD?

Section 2 | Signing Up for OnShape

Section 3 | Navigating OnShape

Section 4 | Your First Stopwatch

Sketches

Section 1 | What is CAD?

CAD stands for Computer-Aided Design, which is exactly what we use it for. We use CAD to design our entire robot in 3d space before we start to build. We do this because by designing entire robots in 3d we can see how parts fit together and interact. This makes designing parts and entire robots much quicker and more efficient.

There are many CAD software's to choose from, but we use Onshape (Other options include: Solidworks, FreeCAD, TinkerCAD and Autodesk Inventor). We use OnShape as it is free to students, easy to pickup, and cloud based, meaning collaboration is claques easier than competing alternatives.

Section 2 | Signing Up for OnShape

Section 3 | Navigating OnShape

The OnShape File System

Now that you've signed up for OnShape, your ready to start your first document. Now you may be wondering, what is a document anyway? Like all file systems, OnShape has documents which can be stored in folders. Both documents and folders can be stored, and accessed on OnShape's home pages.

Onshape's home pages include: Owned by me, Recently opened, Created by me, Shared with me, and Public.

Now this is where it gets confusing. Inside documents you can have Part Studios, Assemblies, and Folders. We will talk more about what Part Studios and Assemblies are for in a moment. But they can be nested in document folders for organization.

These are not the only types of work spaces that exists in documents, but these are the ones which you will use most.

Starting a document

To start your document find and click the "Create" button at the top left of the screen. When the drop down appears click document. Next for you will be prompted to name your document. For right now name it what you please, but we will change it later. Then hit "Create".

Part Studios vs Assemblies

When you start your document, you will start with two work spaces. One Part Studio and One Assembly, but what is the difference? Well...

Part Studios are used to draw parts. For example, if we were CADing a vinyl a record, we could use Part Studios to CAD the individual parts of the record, such as

the record disc it's self, the sleeve, and the gate fold.

Assemblies are used to combine parts into systems. Using the record example again. We could make an assembly of the disc, sleeve and gate fold. Then mate them in a way where they can slide into one another.

To use a robot example. We use assemblies to combine to get a 3d model of the entire robot. By combining individual parts that we designed (3d Printed and Routed Parts) and parts we bought, we can use assemblies to see them fit together and how they move. The majority of the robot to the right is made of polycarb and 3d printed parts. All of which were designed in CAD.

Section 4 | Your First Stopwatch

Now you have all the knowledge you need to start your first CAD project. We will be replicating a simple stopwatch in CAD. The nice part about this exercise is it is easy for anyone to pick up and do. Weather your a seasoned CADer or a complete beginner, you can use your skills to CAD a stopwatch and gain new ones along the way. This exercise will start with the most basic tools and as we go on we will use more and more advanced tools and skills to make our stopwatch more and more like the real thing.

For this activity, it is recommend to grab stop watch and a caliper, but you can do this activity with any reasonably sized object and a measuring tool. I will be showing you how do CAD a stopwatch and what tools are recommended, but there is a million ways to CAD a stopwatch, if you find a way you like more feel free to do it that way!

Sketches

Lets start in the Part Studio. In order to draw parts, you must first start a sketch.

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