Principal Mechanical Engineer

Overview

Principal Mechanical Engineer – Commonwealth Fusion Systems

Commonwealth Fusion Systems is on a mission to deliver the urgent transition to fusion energy. We’re designing and building commercially viable fusion power plants, working with policymakers and suppliers to build the energy industry of the future. We’re looking for new thinkers, doers, builders, and makers to join our team.

Compensation

Base pay range: $/yr – $/yr

Actual salary depends on experience and location and will be accompanied by equity and benefits.

Responsibilities

• Lead the design and implementation of advanced R&D equipment for thin‑film processing, including ownership of key mechanical modules and subsystems

• Define system‑level requirements and drive innovative design concepts to meet these requirements

• Lead design reviews for overall mechanical system and key mechanical subsystems

• Generate and maintain interfaces with other engineering subsystems

• Report on and be accountable for project progress to stakeholders

• Work effectively within a multidisciplinary team of top scientists and engineers

• Mentor engineering staff for effectiveness and delivery of on‑time, in‑spec outcomes

• Drive projects, consistently deliver, and act with speed to get things done

Qualifications

• Master’s degree in Mechanical Engineering or related field (or equivalent industrial experience)

• 15+ years of experience with at least 7 years as a principal mechanical designer or engineering team lead in R&D system and manufacturing equipment

• Ability to conceive novel solutions for complex engineering systems in challenging environments

• Expertise with 3D modeling; experience with Solid Works and NX preferred

• Experience with COMSOL, ANSYS, or other FEA tools

• Ability to select and qualify vendors for components or subsystems

• Demonstrated leadership in direct or matrix structures

• Strong verbal and written communication skills and dedication to high‑quality documentation

Bonus Points

• Ph.D. in Mechanical Engineering or related field (or equivalent industrial experience)

• Prior success building first‑of‑kind or experimental tools for material science or semiconductor R&D

• Familiarity with mechanical standards such as Semi‑S8, ASME, ACI, ASTM, etc.

• Experience operating equipment in a manufacturing environment

Physical & Travel Requirements

• Occasionally lift up to 50 lbs

• Perform tasks such as stooping, climbing, standing, or sitting for extended periods

• Adhere to safety protocols mitigating hazards including heat, cold, noise, fumes, strong magnets, lead, high voltage, and cryogenics

• Willingness to travel or work nights/weekends/on‑call occasionally

Benefits

• Competitive compensation with equity

• 12.5 company‑wide holidays

• Flexible vacation days and 10 sick days

• Generous parental leave policy

• Health, dental, and vision insurance

• 401(k) with employer matching

• Professional growth opportunities and team‑building activities

Legal

You are required to comply with U.S. export control laws. Any offer of employment will be contingent on compliance with such laws.

EEO Statement

We value diversity deeply and are proud to be an equal opportunity employer by choice. We consider all qualified applicants equally, regardless of race, color, national origin, ancestry, citizenship status, protected veteran status, religion, physical or mental disability, marital status, sex, sexual orientation, gender identity or expression, age, or any other basis protected by law.

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