About Commonwealth Fusion Systems: Commonwealth Fusion Systems is on a mission to deliver the urgent transition to fusion energy.
Combining decades of research, top talent, and new technologies, we're designing and building commercially viable fusion power plants. And we're working with policymakers, suppliers, and many others to build the energy industry of the future.
We're in the best position to make it happen. Since 2018, we've raised $4 billion of capital, making us the largest and leading fusion company in the world.
Now we're looking for more thinkers, doers, builders, and makers to join us. People who'll bring new perspectives, solve tough problems, and thrive as part of a team.
If that's you and this role fits, we want to hear from you.
Join the power movement as Principal Mechanical Engineer - Web HandlingWe are looking for a Principal Mechanical Engineer specializing in Web Handling and Roll-to-Roll (R2R) systems to serve as the definitive company-wide technical authority for continuous material processing equipment. In this "First Chair" leadership role, you will shape the overall technical direction, architecture, and deployment of high-precision web transport systems operating in a variety of thermal environments.
You will lead the execution of highly complex, ambiguous cross-functional initiatives that directly impact our core R&D and manufacturing roadmap. Operating with complete independence, you will combine deep technical expertise in web dynamics and precision mechatronics, with strategic leadership establishing division-wide design standards, mitigating significant technical risks, and mentoring the engineering organization.
What you'll do:- Shape R2R System Architecture: Serve as the chief architect for next-generation roll-to-roll equipment, dynamic tension systems, precision accumulators, and high-speed winders/unwinders
- Research Advanced Winding & Unwinding Technologies: Actively research, evaluate, and benchmark next-generation web handling, winding, and unwinding equipment and technologies to inform tool architecture and roadmap decisions
- Lead Cross-Functional Strategy: Translate complex scientific R&D objectives into actionable engineering architectures, bridging mechanical design, process physics, electrical hardware, and closed-loop controls across multiple project groups
- Master Web Dynamics & Technical Risk: Drive advanced dynamic modeling, web physics analysis, and experimental validation to resolve critical web defects (e.g., thermal buckling, lateral drift, scratching, or tension transients) in flexible metal substrates
- Establish Division Standards: Institutionalize company-wide engineering standards, design guidelines, and testing methodologies for web handling, precision roller design, bearing selection, and mechatronics
- Drive Process & Tool Innovation: Pioneer novel mechanical concepts, dynamic guiding schemes, and non-contact web transport modules operating inside temperature zones
- Independently Manage Risk: Identify, evaluate, and mitigate high-impact technical risks across major equipment initiatives, establishing contingency paths and robust design margins
- Direct Strategic Vendor Partnerships: Audit, qualify, and direct global suppliers and contract manufacturers for specialized R2R sub-assemblies, precision ground rollers, custom surface coatings, and drive components
- Organization-Wide Mentorship: Actively coach and mentor Staff, Senior, and Junior mechanical engineers, elevating technical rigor, design review standards, and professional development across the discipline.
What we're looking for:- Education: Master's or PhD in Mechanical Engineering, Mechatronics, or a related field (or equivalent specialized industrial experience)
- Experience:15+ years of proven track record as a recognized technical leader in the architectural design, scaling, and implementation of complex web handling, roll-to-roll (R2R), or converting equipment
- Deep Domain Expertise: Authoritative knowledge of web handling physics-closed-loop tension control, winder dynamics, lateral guiding, roller traction, nip mechanics, load cell integration, and substrate stress distribution
- Cross-Disciplinary Mastery: Demonstrated capability to integrate mechanical systems seamlessly with advanced motion controls, power electronics, and thermal management systems
- Proven Track Record in High-Stakes Tooling: Successful history of bringing first-of-a-kind continuous processing capital equipment from concept through commissioning and high-yield operational scale
- Influential Leadership: Demonstrated ability to drive technical consensus and lead multi-disciplinary teams without relying on formal line management authority
Bonus points for:- CAD & Simulation Leadership: Advanced mastery of 3D CAD platforms (SolidWorks and/or NX) paired with expertise in multi-body dynamics, non-linear FEA, and finite-difference web simulations
- Brittle & High-Strength Substrate Transport: Specialized experience handling narrow metal tapes, high-strength alloys, or delicate multi-layer composite webs
- Advanced Motion & Control Loops: Deep familiarity with tuning multi-axis servo drives, dancer control algorithms, and adaptive tension loops
Must-have Requirements:- Ability to occasionally lift up to 50 lbs
- Perform activities such as stooping, climbing, standing, or sitting for extended periods of time
- Dedication to safety to mitigate industrial hazards that may include heat, cold, noise, fumes, strong magnets, lead (Pb), high voltage, and cryogenics
- Willingness to travel or work required nights/weekends/on-call occasionally
$187,000 - $270,000 a year
Salary range for this full-time position + equity + benefits. The actual salary will depend on level, location, qualifications, and experience. The range displayed on each job posting reflects new hire salaries for the position across all US locations.
Benefits include:
Competitive compensation with equity
13 Company-wide Holidays
Flexible vacation days
10 sick days
Generous parental leave policy
Health, dental, and vision insurance
401(k) with employer matching
Professional growth opportunities
Team-building activities
At CFS, we excel in fast-paced environments, driven by our values of integrity, execution, impact, and self-critique. As we grow, we're eager to bring on mission-driven folks who offer diverse perspectives and fresh ways to tackle challenges.
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.
This role requires compliance with U.S. laws concerning the export of controlled or protected technologies or information (collectively, "Export Control Laws"). Any offer of employment will be contingent on the need for compliance with such Export Control Laws. 
