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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. 2| Design Review. Include : Current Design Issues Relevant Calculations CAD / Design Layout Images Modeling
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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 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 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? Chris D. McCoy| Berkeley Mechanical Design
Case Study #1 Small scale engine dynamometer 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 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: Chris D. McCoy| Berkeley Mechanical Design
3| Design Reflection: 1 Sept. 2008 • Reflection: • 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 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! Chris D. McCoy| Berkeley Mechanical Design