Onshape CAD Primer
By C. A. Mattson
Use the CAD software while reading and doing the activities described in this tutorial. Each one is designed to familiarize you with CAD and efficiently get you to the point where you can thrive in the deep end, where you'll be when facing the challenging design problems in the rest of the course.
Remember that there are many good ways to model the turbocharger gasket you'll create in this sprint. However, the primary goal of the activities in this chapter is not for you to create a gasket. Instead, the primary goal is to expose you to various good ways to interact with the CAD system. As such, do the activities as they are described, decide what works well for you, and begin cataloging workflow options that accelerate your work.
Above all, do the reading and the learning activities to learn; do not simply get them done. Exercise curiosity; look at menu options, press buttons, and break things. Learn to undo, restart, and read warning messages, as these will help you explore.
Part 0: Set up
In the other parts of this sprint, you will explore the turbocharger, manipulate it, and create two gaskets to create a proper seal between it and other parts it mates to.
To access the turbocharger document for the next activities, do the following:
Step 1: Have an Onshape account.
Step 2: Click on this link to the Turbocharger Document.
Step 3: Copy the view-only Turbocharger Document to your own workspace. (Use the three-bar horizontal menu in the upper left region of the Onshape screen.)
Step 4: Appropriately rename and file the document.
By doing these steps, you now have a personal copy of the turbocharger document.
Part 1: Navigating the CAD System:
Activity 1 (Zoom, Orient, and Pan): https://youtu.be/BRcoiwJV2NE
Activity 2 (Change the Visibility of Objects): https://youtu.be/Oid5zdPt-zY
Activity 3 (Create Cross Section Views): https://youtu.be/6LqDis9nGpU
Activity 4 (Change the Material Specification): https://youtu.be/ZCXNr7zxXYI
Activity 5 (Change the Bolt Pattern): https://youtu.be/dE92hcbt6ls
Activity 6 (Change the Sensor Port): https://youtu.be/9ia-JJVUnoQ
Activity 7 (Change Model Units): https://youtu.be/f71jF8ayeUg
By doing the activities above, you experienced three important things:
How CAD facilitates information sharing. Imagine how difficult it would have been for me to describe the turbocharger geometry to you if we did not have a CAD model.
How CAD facilitates visualization and exploration. Without a doubt, you better understood the turbocharger as you interacted with it by rotating it, zooming in on details, and making cross section views.
How CAD facilitates design changes, such as changing from 8 to 16 bolt holes. Imagine how valuable design iteration can be with an easily changeable CAD model.
You now know enough about workspace navigation to start creating your own 3D geometry.
Part 2: Create Geometry in the CAD System:
Activity 8 (Create Gasket Substrate): https://youtu.be/pKueV3vYKKg
Activity 9 (Edit Gasket Substrate with Version Merging): https://youtu.be/IH9HxtnIYNU
Activity 10 (Resolve Over-defined Sketches): https://youtu.be/6CPtCm3wuD8
Activity 11 (Edit Gasket Substrate Extrude): https://youtu.be/HsawH-nFcaE
Activity 12 (Edit Gasket Placement in Space): https://youtu.be/m7u5045nXck
Activity 13 (Add Center Cutout to Gasket): https://youtu.be/uqpvUb2tk1Q
Activity 14 (Add Bolt Holes to Gasket): https://youtu.be/cMN9cK6ggmg
Activity 15 (Round the Gasket Corners): https://youtu.be/p-7PGbtSVnQ
By completing these activities, you have learned enough about CAD sketching to create a geometrically correct and materially correct gasket for the turbocharger.
Through the activities, you learned the following:
how 3D geometry is constructed from simple 2D shapes, such as rectangles and circles
specifying shape (e.g., rectangle), specifying size (e.g., 268 mm gasket length), and specifying location or placement in space (e.g., rectangle corner coincident with origin)
geometric relations and how to add and delete them
how to create and edit three simple 3D CAD operations (extrude, cut, and fillet)
how to evaluate the parts you created using a simple mass properties evaluation
the importance of creating fully defined sketches and how to make them
Having completed the activities, I am convinced you can create any simple CAD sketch accurately. And since most CAD sketches are simple, you are well on your way to being able to produce CAD models of complex parts.
Part 3: Advanced Approaches to Creating the Turbo Charger Gasket
Activity 16 (Trim): https://youtu.be/0KZxtWWGn6s
Activity 17 (Convert Entities, Offset, Extend): https://youtu.be/tgVD444UBCk
Activity 18 (Sketch Fillets): https://youtu.be/0QMnCA_ngEU
Activity 19 (Feature Mirror): https://youtu.be/wBgvFk3RwzI
Activity 20 (Sketch Mirror): https://youtu.be/1-UncJRGbps
Activity 21 (Feature Pattern): https://youtu.be/TCA-a6ETn14
Activity 22 (Sketch Pattern): https://youtu.be/cumkXOnblAM
Activity 23 (Evaluate the Part Using Measure): https://youtu.be/X2DkLbWNh_8
By investing the time to do the activities described above, you now have significant practice and knowledge about the following:
switching between 2D workspace and 3D workspace
creating new sketches
editing existing sketches
dimensioning features
adding and editing geometric relations
making lines, circles, rectangles, and sketch fillets
turning lines into construction lines
converting sketch entities from one sketch to another sketch
offsetting entities
trimming and extending lines
mirroring in features
mirroring in the sketch environment
patterning features
patterning in the sketch environment
version control, including branching and merging
making and editing extrudes, cuts, and fillets in the 3D workspace
carrying out a simple mass properties analysis and measuring entity size and location using the measure command in the 3D workspace
Although these items may seem insignificant and were carried out on a mundane object (a gasket), your awareness and growing skill in each of these areas enable you to speak the CAD language and prepare for mechanical design.