Chris D. McCoy| Berkeley Mechanical Design 1| Design Brainstorm Overview of project Goals of Project Include: Preliminary sketches / pictures to aid discussion Design Criteria: Must Haves Should Haves Nice to Haves 11/12/2018 Chris D. McCoy| Berkeley Mechanical Design

Chris D. McCoy| Berkeley Mechanical Design 2| Design Review Include: Current Design Issues Relevant Calculations CAD / Design Layout Images Modeling What questions do you want to have answered? Etc. Design Review Goals: To make any last minute needed design changes Build confidence that your design is complete and ready for sourcing / fabrication 11/12/2018 Chris D. McCoy| Berkeley Mechanical Design

Chris D. McCoy| Berkeley Mechanical Design 3| Design Reflection Include: Final design (CAD) Final Design (physical images) Test results Etc. What worked / What didn’t work Best feature of design Worst feature of design What did we / you forget? Reflection Goals Figure out how we can improve for future designs What are people most proud of What did you learn from this experience? What would you do differently next time? 11/12/2018 Chris D. McCoy| Berkeley Mechanical Design

Small scale engine dynamometer Case Study #1 Small scale engine dynamometer 11/12/2018 Chris D. McCoy| Berkeley Mechanical Design

1| Design Brainstorm: 31 Jan 2008 Overview of project: Need a robust, precision aligned, dynamometer to measure output mechanical power of a small scale hobby engine Research will include the testing of several liquid fuels with engines at high temperatures, moderate vibration, etc. Goals of Project Buy or build a dyno that can measure power, torque, temperature, etc. in a timely fashion Design Criteria: Must Haves Low cost Precision alignment of engine shaft to electric motor shaft Ability to start engine / measure power Adjustability / flexible Fit on test bench Should Haves DFA - Easy to disassemble DFM Nice to Haves Easy to machine Quick lead time 11/12/2018 Chris D. McCoy| Berkeley Mechanical Design

Chris D. McCoy| Berkeley Mechanical Design 2| Design Review: 26 Feb 08 Include: What material is resistant to fuels? How do I achieve precision alignment? Where should I have this machined? What else should I consider? What am I forgetting? Design Review Goals: 11/12/2018 Chris D. McCoy| Berkeley Mechanical Design

3| Design Reflection: 1 Sept. 2008 Total cost: ~$1500.00 What worked: Output power and torque can be measured well What didn’t work: Design for assembly / disassembly could have been improved. More room for tools (socket sets / allen keys) Use all English screws and hardware. Machinists prefer it and it’s easier/cheaper to find hardware Starting engine w/generator was tricky (in terms of speed controller usage) Best feature of design: Quick adjust / removal for engine mount Worst feature of design: Torque measurement arm– too much vibration, very noisy, consider cradle dyno for the future. What did we / you forget / not consider? Holes for screw access w/tools (easy post modification in machine shop) Methanol degrades Aluminum Oxide (according to internet) Dynos on this scale CAN be purchased from Magtrol Consider lift hooks / handles to remove slip fit / heavy components Forgot cooling ducts Add wire routing guides (for stress relief) Don’t design in 4-40 or M3 tapped holes (breaking taps) Final images Magtrol dynos 11/12/2018 Chris D. McCoy| Berkeley Mechanical Design

Interested? Need Help? Contact If you’d like to participate or need help with a mechanical design – please contact me at: mccoy@eecs.berkeley.edu If this PPT was helpful could be improved, please let me know! 11/12/2018 Chris D. McCoy| Berkeley Mechanical Design