Senior Drivetrain Engineer Jobs in California (NOW HIRING)

The Role

LettrLabs is reinventing direct mail. With our own in‑house handwriting robotics, we’re challenging traditional direct mail manufacturing from the ground up. We’re looking for a Senior Mechanical Design Engineer to own the mechanical design and development of complex electromechanical systems from concept through production — and to be instrumental in building our next‑generation production automation platform.

You’ll take projects end‑to‑end: translating requirements into robust, manufacturable designs, validating them through analysis and prototyping, and seeing them through to commissioning. You’ll work closely with cross‑functional partners in electrical, controls, manufacturing, and quality, as well as external vendors and suppliers. This is a hands‑on, high‑ownership position for an engineer who is equally comfortable at a whiteboard, in CAD, and on the shop floor.

Why Join Us

• Design the machines that make our product possible — you’re not supporting a production line, you’re building it.
• High ownership from day one: end‑to‑end accountability for complete mechanical systems, not isolated components.
• Work alongside a team of engineers who bring the same grit and ownership mindset to every problem.
• Real exposure to leadership and cross‑functional partners — your design decisions are visible and matter.
• A culture of grit, perseverance, and performance that values engineers who get energized by hard problems.
• Competitive compensation, growing benefits, and a culture that rewards initiative.

What You Will Own

• Own entire mechanical systems and sub‑systems across the full product lifecycle — requirements generation, concept development, detailed design, analysis, prototyping, validation, and commissioning.
• Design precision motion systems incorporating belts, pulleys, gears, bearings, shafts, and related drivetrain components.
• Develop sheet‑metal components and assemblies with a strong understanding of manufacturing processes and tolerances.
• Apply DFM/DFA principles to drive cost, quality, and reliability across every design decision.
• Perform engineering analysis using hand calculations and FEA to size components, validate designs, and de‑risk failure modes.
• Select appropriate materials and finishes based on structural, thermal, environmental, and cost requirements.
• Build and test prototypes rapidly to validate concepts and iterate quickly toward production‑ready designs.
• Create and maintain detailed engineering drawings, GD&T, BOMs, and design documentation.
• Mentor junior engineers and contribute to design reviews and best practices.

What Success Looks Like

• Mechanical systems delivered on time from requirements through commissioning with minimal rework.
• Designs that pass validation the first time — rigorous analysis and prototyping reduce costly late‑stage surprises.
• Cross‑functional partners describe you as someone who makes integration easier, not harder.
• Junior engineers improve measurably through your mentorship and design review participation.

What You Bring

• 5+ years of experience in mechanical design and product development.
• Deep, hands‑on experience with motion systems and their core components — belts, pulleys, gears, bearings, and shafts.
• Working expertise in sheet‑metal design and the associated manufacturing methods (bending, CNC machining, laser cutting, waterjet, additive manufacturing).
• Strong command of Design for Manufacturing and Design for Assembly (DFM/DFA).
• Strong fundamentals in mechanical engineering — statics, dynamics, mechanics of materials, tolerancing.
• Proven experience with FEA and hand calculations to drive and validate design decisions.
• A track record of owning complete mechanical systems and sub‑systems from requirements through commissioning.
• Experience working directly with vendors and suppliers throughout design and manufacturing.
• Bachelor’s degree in Mechanical Engineering or a related field.

Nice to Haves

• Master’s degree in Mechanical Engineering or a related discipline.
• Experience in robotics, automation, or industrial machinery.
• Proficiency with SolidWorks, NX, or similar CAD platforms and PDM/PLM systems.
• Familiarity with GD&T (ASME Y14.5) and tolerance stack‑up analysis.

$150,000 — $180,000 USD

Actual base salary offered will be determined by experience, skills, and work location. This range is for base salary; our total compensation includes equity and benefits. We welcome you to apply even if your expectations are outside our listed range.

LettrLabs is committed to creating a diverse environment and is proud to be an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, gender, gender identity or expression, sexual orientation, national origin, genetics, disability, age, or veteran status.

LettrLabs is committed to providing reasonable accommodations for qualified individuals with disabilities in our job application procedures and throughout employment. If you need assistance or any accommodation, please let us know.

LettrLabs does not accept unsolicited resumes from recruiters or employment agencies without a fully executed recruitment agreement in place. In the absence of such agreement, LettrLabs reserves the right to pursue and hire any candidates without an obligation to pay fees. Agencies are requested not to contact LettrLabs hiring managers or employees regarding recruiting services.