Senior Mechanical Engineer - Assembly Equipment

Commonwealth Fusion Systems LLC; Massachusetts; On-site; USD 110,000 - 185,000; Full time

Job summary

Commonwealth Fusion Systems LLC seeks a Senior Mechanical Engineer to design, develop, and manage tooling for SPARC assembly. You will own tooling concepts, engineering strategy, and use, collaborating with system teams to ensure safe, cost‑effective integration of tokamak components on site.

Lead tooling fabrication oversight, write assembly work instructions, and coordinate with engineers, designers, and the Tokamak Assembly team to meet aggressive milestones in a high‑stakes research

Qualifications

• BS in Civil, Mechanical, or Aerospace Engineering.
• 7+ years of mechanical engineering with project ownership.
• 4+ years overseeing construction, manufacturing or assembly.
• 4+ years of CAD experience.

Responsibilities

• Own the design and development of tooling, lifting, manipulation, and support frames for SPARC components.
• Guide assembly steps and optimize tool use in collaboration with system teams.
• Analyze tool structures and kinematics to ensure safe movement and operation.
• Prepare work instruction packets and supervise tool fabrication and on‑site activation.
• Coordinate with tooling engineers, designers and assembly teams to meet requirements.

Skills

Mechanical engineering

Project ownership

Construction/assembly oversight

CAD software

Siemens NX

Education

BS in Civil, Mechanical, or Aerospace Engineering

Tools

CAD software

Job description

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 a Senior Mechanical Engineer

As a Senior Mechanical Engineer on the Assembly Team at CFS, you design, develop, and manage fabrication of the wide variety of unique tooling needed for the successful assembly and integration of the SPARC tokamak device. This will entail the development of the overall concept, engineering, and use strategy of each tool assembly, and of the assembly step that the tool will facilitate. You will work closely and collaborate with the system teams to find the most efficient, creative, cost-effective, and safest way to manipulate, guide, and integrate each part of the larger tokamak system, design and build the tools needed, then finally write work‑instruction packets that guide the use of the tool at the time of assembly. You will use your expertise on our most complex, largest, and most critical tools and manipulations, ensuring completion of the most challenging parts of SPARC assembly. You will guide and create how the giant parts of this multi‑million pound "swiss‑watch" come together, and the mega‑tools to do it! This work is conducted within a multi‑disciplinary team of physicists and engineers as part of collaborative sponsored research projects at the MIT Plasma Science and Fusion Center and within CFS.

What you’ll do:

• Ownership, design, and complete engineering development of the tooling, lifting, manipulation, and support frames for successful movement, handling, guidance, and integration of SPARC system components.
• Formulate the general strategy for each assembly step utilizing these tools, as well active coordination and guidance of the system teams during parallel design activities for optimum assembly logic, steps, best practices, methods, strategies, and other details.
• Analysis of the tool structures and kinematics to ensure that the tool can adequately and safely conduct the movement or support as designed.
• Within the plan development, ensuring tool and personnel access is available as required for system assembly steps as outlined by the system owners.
• Assist development for the alignment plan for precision placement for magnet and vessels by providing tools for successful handling and manipulation of parts to meet alignment requirements.
• Responsible for the plans for part movement at each step and ensuring no interferences with other systems during movement.
• Oversight over fabrication of the tools at outside vendor shops, with guidance and troubleshooting to ensure the tool is built to the specifications required.
• Specification and procurement of all purchased hardware required for the tools.
• Responsible for the assembly work instruction packets for each tool, to be used during the assembly phase of SPARC, as well as the assembly, proofing, and activation of the tools in your ownership on-site.
• Work with other tooling engineers, designers, and assembly package coordinators, as well as direct personnel performing the Tokamak Assembly during on‑site work in the use of your tool and related assembly step.
• Work with teammates in a collaborative fashion to receive feedback early and often to ensure all requirements are met. Many SPARC projects involve high loads, vacuum requirements, and complex manipulation requiring the involvement and review of adjacent sub system experts.

What we’re looking for:

• Civil, Mechanical, or Aerospace Engineering B.S.
• 7+ years of Mechanical Engineering Experience demonstrating project ownership
• 4+ years experience overseeing an in‑progress construction, manufacturing, or assembly/integration process
• 4+ years of experience with CAD software

Bonus points for:

• 3+ years of experience with Siemens NX
• Lifting operations experience
• Knowledge of welding
• Knowledge of piping and tubing construction and joining
• Experience with highly complex or delicate assemblies
• Experience with assembly or integration in tightly packaged spaces
• Experience with fast‑paced and dynamic construction, manufacturing, or assembly/integration builds
• Design of simple yet sizeable alignment and positioning fixtures
• Heavy component manipulation and welding of large structures

Must-have Requirements:

• Ability to occasionally lift up to 50 lbs
• Perform activities such as typing, standing, stooping, climbing or sitting for extended periods of time
• Required onsite 5 days/week when assembly operations with relevant tools are underway, with possible first or second shift assignment
• Work in a facility that contains industrial hazards including heat, cold, noise, fumes, strong magnets, lead (Pb), high voltage, high current, pressure systems, and cryogenics

$110,000 - $185,000 a year

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.