This hands-on course explores design, fabrication, and assembly of toy products for the DIY community. Working in teams, students will design, fabricate, and assemble toy cars consisting of functional mechanical assemblies of multiple parts (wheels, chassis, gears, differential gears, shell, etc.) with specific functional requirements (e.g. wheels must rotate, parts must snap-fit, etc.). Toys must be designed for laser cutting fabrication and easy manual assembly with no adhesives or fasteners. Students will explore flexure joints and Design For Assembly (DFA) techniques to easily install parts. Depending on available time and resources, students may integrate motors to actuate their toys. Each student in a team will develop (design, CAD model, and fabricate) a part or sub-assembly, negotiating with the other teammates about how their parts/sub-assemblies will interlock. Students must negotiate what they can design, design what they can model, model what they can fabricate, and fabricate what that they can assemble. Exchange of data will take place using spreadsheets and import/export functions.

Students will learn fundamentals of parametric and computational CAD modeling using Rhino and Grasshopper, and occasionally C#. Furthermore they will learn how to design gears to transfer torque, as well as basic principles of Design for Assembly (DFA) such as flexure snap-fit joints, economics, and production planning. Students will also study the qualities of assembling their prototypes using graph theory. All projects, their progress, and instructions for replicating them will be documented on this blog.

Project Assignment

You will formulate teams of two. Each team must design, fabricate and assemble a toy car that will be able to store energy and transmit it to its wheels for locomotion.

Each toy car must consist of two subassemblies: motor and main chassis. Each teammate will develop a subassembly. Subassemblies must interconnect with gears and snap-fit or flexure joints.

One student will design the gearbox/motor. This will receive energy, store it, and transmit it. It will have to be a self-standing, stand-alone mechanical assembly that will be inserted to the chassis of the car. Motors can consist of a flywheel or a pullback mechanism with a torsion spring /coil.

The second student will design the chassis of the car. This will consist of the chassis (body), the wheels with their axes, and potentially a shell/cover. The wheels/axes must have integrated gears to receive the transmission from the gearbox that the other student in your team will make.

Your decisions about how many connections your subassemblies will have with each other as well as each one internally is crucial for the success of the project.

You are allowed –but not required– to use one off-the-shelf mechanical component, provided that it is easy to find. Examples may be a pulley-wheel (to use as a flywheel), ball-bearings, metal rods, etc. You will be judged on your ability to give aesthetic values on functional requirements. Your toy must be easy to build.

Pay attention to the power transfer function. How much energy can your car store and how far can your it travel? You must exemplify skills on assemblies and mechanical design.

Attention: The course is NOT about tinkering. Instead we are interested on inventing solutions that are compatible with the available materials and fabrication techniques and aesthetically pleasant. You should consider your projects not as rough prototypes but as finished products. During the final reviews, teams will compete based on how far their toy cars can go.


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