Senior Field Mechanical Engineering - Assembly

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 and suppliers to build the energy industry of the future.

We’re in the best position to make it happen. Since 2018, we’ve raised nearly $3 billion in capital, making us the largest and leading private 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.

As the Senior Field Mechanical Engineer on the Assembly Team at CFS, you will manage, oversee, and provide engineering solutions for the most complex and unique SPARC assembly workstations. You will own the entire assembly sequence of your workstation, coordinate with technicians, procure or design tools, and collaborate with adjacent teams to ensure alignment, precision, and efficient progress of the project.

• Own and be the expert in the assembly sequence of your workstation (initially the assembly of the Toroidal Field Coil sub‑assemblies), determining and enacting acceptable solutions and changes that fit the overall SPARC assembly sequence.
• Lead first‑encounter scope definition, including installation of manifolds and magnet sub‑assemblies.
• Identify, analyze, and resolve assembly issues—fit, method, or handling—working with Tokamak System design teams to modify parts or processes while meeting functional requirements.
• Proactively procure or build all tools, fixtures, or manipulation equipment necessary for upcoming ports in your workstation.
• Act as the ultimate owner of a process by testing, implementing, and handing it off to production technicians for repeated use.
• Provide design feedback to SPARC subsystem designs with a focus on manufacturability and assembly, participating in formal and informal design reviews.
• Assist in disposition and resolution of non‑conformance issues on parts or processes, incorporating red‑line changes into updated sequences.
• Support hands‑on operations during Tokamak Assembly, serving various roles throughout the process.
• Collaborate with teammates to receive early feedback, ensuring all requirements are met for high‑load, vacuum, or complex manipulation tasks.

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

• 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, dynamic construction, manufacturing, or assembly/integration builds.
• Design of simple yet sizeable alignment and positioning fixtures.
• Heavy component manipulation and welding of large structures.

• Ability to occasionally lift up to 50 lbs.
• Perform activities such as typing, standing, stooping, climbing, or sitting for extended periods.
• Required onsite 5 days/week during active assembly operations, with possible first‑ or second‑shift assignments.
• Work in a facility containing industrial hazards including heat, cold, noise, fumes, strong magnets, lead, high voltage, high current, pressure systems, and cryogenics.

$110,000 – $185,000 a year

• 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.

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At CFS, we excel in fast‑paced environments, driven by our values of integrity, execution, impact, and…