The Design Sub-Team is responsible for the CAD/CAM designs used to build the robot. In order to make good designs it is necessary to understand the manufacturing and mechanical sub-team’s jobs very well. It is quite challenging to make a design that is easy to manufacture, easy to assemble, and easy to maintain.

We use Autodesk Fusion 360 as our design software. Each season we create a new Project that is used for all of the design files. It is important to keep the project directory organized with folders that contain the components for each logical sub-component of the robot (i.e. frame base, drivetrain, arm, intake, turret, etc.). There is also a Vendor folder that contains some of the 3D models from the various vendors we use for Commercial Off-The-Shelf (COTS) items organized into subfolders.

Most of the FRC parts the are used on the robot have 3D model files of the item available (STEP files). The Vendor folder in the Project directory contains the models that have been downloaded. If you need to add an item that isn’t there then put it into the correct subfolder and use a file name that makes sense. For example, 1/2" Hex Rod from WCPs website might be named HEX_ROD_0500_WCP_217-2753 which tells everyone what it is, where it was downloaded from, and the part number(look at the other items there for other examples). Do not modify the vendor files directly. If you need to modify a part (e.g. shorten hex rod) then insert the component into your design and break the link between it and the vendor file. It can then be modified without changing the original vendor file.

Fasteners can also be inserted directly into a design using the Insert → Insert McMaster-Carr Component command. Search for the item you need on the McMaster-Carr website that pops up and then select "3D STEP" as the file type and click Download. McMaster-Carr has many types of fasteners including nuts, bolts, washers, e-clips, hex keys, etc.

Moving and aligning imported components is done by rotating the component to the proper orientation then using a Point-To-Point move to get the component to the correct X,Y,Z location. It is usually easiest to select circles (or arc centers) as the source and target "points".

Unless you are making a single part made of a single body you should create components for each part of your design AND BE SURE TO ACTIVATE that component when you are working with it. Most of the advanced functionality of Fusion 360 only works with components such as joints and rigid body constraints. Activating a component before doing any operations on it will filter the timeline to only those that pertain to that component which makes working with the timeline much easier as designs get complicated.

See Components & Bodies for New Designers

Each part of the robot should be designed (CAD and CAM) in its own design file. The complete robot is then assembled from the individual component design files. It may make sense for some design files to contain multiple components but generally having a single component per design file makes compartmentalizing the CAD and particularly the CAM elements easier.

Belts, Chains, and Gears are commonly used on FRC robots. When a design uses these elements it is possible to choose the distance between rotation centers such that exact lengths of belts or chains work correctly. Gears will not work without precise center-to-center distances. A great deal of very good information can be found in the WCP FRC Build System documenation.

Design team members must understand the various fasteners available. Designs need to take into consideration clearances for fasteners and fastener heads. Designs also need to specify the correct hole sizes for holes that will be threaded or for bolt clearance.

Details of fasteners are given in Mechanical Sub-Team — Fasteners

Bearings come in inch and metric sizes with metric bearings having many more sizes available. Bearings have a standardized numbering system to determine their size. For example, a 10mm ID x 22mm OD bearing has a number of 6900 which can be looked up in bearing tables (Miniature Bearings, Standard Bearings).

There are several commonly used mechanisms in FRC. The Team 5985 Mechanism Encyclopedia has a ton of information about the different types with links to more information. There is also a set of slides by Team 2471 that outlines manipulators (particularly elevators).

Making complex designs using a CNC machine (i.e. the ShopBot and the HAAS) requires creating instructions for how the cutting tools must move. Those instructions are "post processed" into a NC program file that the CNC machines read. Fusion 360 can be used to create the machining tool paths and convert them to NC programs.

A great resource for learning CAM modeling is the Titans of CNC Building Blocks Series. This series gives both CAD and CAM instructions for creating parts and generating the NC program. Students in Engineering II sometimes make the Titan-4M part. If you have good CAD skills then it is useful to only look at the drawing PDF and generate the CAD model from the PDF before watching the CAD video. Then watch the video on how they created CAD model. They sometimes use different techniques which gives you an alternative method of doing the same thing.

See also: Manufacturing Sub-Team — HAAS Mill