Mechanical Design Engineer, Powertrain

About Tau Power conversion is the bottleneck between the compute, energy, and mobility industries and the future they're trying to build. Most of the industry is still solving it with decades-old approaches. Tau is fixing that. We're a venture-backed hardtech company in Redwood City, building power conversion technology for data centers, EVs, and energy systems. Several products are already moving into production.  We hire people who own problems end-to-end: power electronics, embedded software, controls, test and validation, mechanical design. We solve from first principles, not legacy playbooks. We're past "promising technology." Customers are buying, volume is coming, and the people who join now set the standard everyone builds on after. Who you are You're practical, not precious about your own ideas. You'll defend a design decision with data, and drop it just as fast when better data shows up. You understand that automotive standards aren't a formality. Qualification, reliability, and durability requirements exist because failure in the field is expensive and dangerous, and you treat them as real constraints, not checkboxes to satisfy on the way to the interesting part. You communicate problems before they become surprises. If a program is off track, you say so immediately with enough details that someone can act on it. Silence is the failure mode here, not an honest "this is behind" Our Engineering Approach Solve customer problems, not engineering puzzles. Great technical work becomes exceptional when it creates reliable products, enables meaningful new capability, and solves real customer problems. Think in systems. Understand how your work affects the complete product and the people who build it. Make tradeoffs that improve the whole, not just your direct area of ownership. Exercise judgment. Apply the engineering rigor the risk requires. Make timely decisions with the available evidence, communicate uncertainty, and balance technical excellence with program needs. Raise the standard. Deliver quality work on time, improve how the team works, and leave the products, systems, tools, and people around you better than you found them. About the role This role is about taking mechanical designs to automotive-grade production. The bar is qualification: will this pass, will it hold up over the life of the vehicle, will it manufacture repeatably at volume. The schedule is real, and so are the consequences of missing it. You'll understand the spec, including automotive qualification requirements, deliver against it, and say something the moment it's at risk. If a design won't hold up under vibration testing, or a supplier is slipping, we want to know at week one, not week six. Good design and fast delivery aren't in tension here. We just don't reward cleverness that doesn't serve the spec. You'll have real input into design decisions and pushback rights when a spec seems wrong; this isn't execution-only. But if you'd rather defend your own solution than hit what the program actually needs, this isn't your seat. We're open to a range of seniority, including someone who could eventually run the team. Seniority isn't the bar. Competence is: do you consistently deliver what you said you would, communicate clearly the moment you can't, and stay focused on what the program needs over what's interesting to you personally. Because our success depends on collaboration, we expect new employees to work onsite five days a week to build strong working relationships with the team. Areas of ownership Mechanical Design Lead mechanical integration of electric machines and powertrain hardware: rotors, stators, housings, shafts, bearings, cooling systems, structures, enclosures, interfaces Weigh in on design decisions and specs, not just execute against them Produce clear models, drawings, and specifications that others can build from without guessing Analysis and Validation Own DVP/DVP&R that connects requirements, including automotive qualification requirements, to actual evidence Run or guide structural, thermal, fatigue, and tolerance analysis at the depth the risk actually requires Contribute to DFMEA and design reviews Correlate analysis against physical test results Production scaling Take designs from prototype toward automotive-grade production: repeatable, qualifiable, manufacturable at volume Apply DFM and DFA throughout, not as a final check Produce complete drawings and manufacturing requirements with correct GD&T and tolerancing Work with suppliers and manufacturing to resolve quality, cost, and assembly issues at production scale Cross-functional work Work with Electric Machine Design, Power Electronics, Embedded Software, Controls, Test Systems, Manufacturing, and Program Management Communicate requirements, risks, and status without being asked Make tradeoffs and decisions visible to the people who need to know, and explain prioritization in terms of what the program actually needs Technical foundation You'll likely have working knowledge of some mix of the following: Mechanical design of complex electro-mechanical systems CAD, engineering drawings, design documentation GD&T and tolerance-stack analysis First-principles analysis and FEA Rotor dynamics, fatigue, or thermal analysis DVP/DVP&R and validation Automotive qualification standards (AEC-Q, ISO 16750, or similar) DFMEA or equivalent risk assessment DFM, DFA, and common manufacturing processes at volume Root-cause analysis and structured problem solving Experience Five years developing complex electro-mechanical, powertrain, rotating-machinery, or similarly demanding hardware, ideally including exposure to automotive qualification or production scaling. A bachelor's degree in Mechanical Engineering or a closely related field, or equivalent demonstrated experience.  Electric-machine or powertrain experience is a plus but not requi