Mechanical Engineer

1\. Overview

We are hiring experienced mechanical engineers to work directly with a leading AI lab's research and program management teams, improving how frontier AI models reason about real mechanical engineering work.

Your engineering judgment is the substance of this role. You will review the quality of mechanical engineering tasks and model outputs, write the instruction specs and reference solutions that define what "correct" looks like, and help build the evaluations that show whether the model is genuinely improving. We are looking for practicing engineers who have owned real designs, analyses, or systems in industry, not generalists.

This is a W-2 employment position with Cincinnatus LLC, with the opportunity to be placed at a leading AI lab as part of their extended workforce. The initial engagement is 2 to 3 months, with a strong possibility of extension based on performance and project needs. You will be provisioned with client-issued accounts and equipment, and will work inside the client's own tools alongside their research teams.

Location: Remote, within the United States.

2\. Key Responsibilities

• Data QA and reviews: Vet the quality of mechanical engineering tasks and model outputs, spotting incorrect assumptions, missing constraints, unit and tolerance errors, unsafe design choices, and answers that read well but would not pass a design review.
• Instruction specs and reference solutions: Write clear instruction specs, produce worked reference solutions to mechanical engineering problems, and define new tasks that reflect how engineering work is actually done in practice.
• Benchmarks and domain depth: Design challenging tasks and evaluation sets across areas such as mechanical design, thermal and fluid systems, structural and stress analysis, manufacturing, and controls, and help build domain-specific tools together with the research team.
• Calibration: Work with client researchers and specialists in adjacent fields to keep standards consistent, translating tacit engineering judgment into explicit, teachable criteria.

3\. Core Qualifications

• Education: Bachelor's degree or higher in Mechanical Engineering or a closely related engineering discipline.
• Experience: 5+ years of hands-on professional mechanical engineering experience in industry, for example product design and development, thermal and fluid systems, HVAC, structural or stress analysis, manufacturing engineering, automotive, aerospace, energy, robotics, or medical devices.
• Domain depth: Genuine ownership of real engineering work, for example designing components or systems, running FEA or CFD analyses, releasing drawings and specifications, or taking products through design reviews, testing, and production.
• Tools and standards: Working fluency with common engineering tools (for example SolidWorks, CATIA, NX, Creo, AutoCAD, ANSYS, Abaqus, or MATLAB) and familiarity with relevant codes and standards (for example ASME, ASTM, ISO, and GD&T per ASME Y14.5).
• Seniority: Clear progression toward senior or lead engineering responsibility. A Professional Engineer (PE) license is a plus but not required.
• AI fluency: Hands-on working use of large language models in your professional work, and the judgment to tell a well-reasoned answer from a plausible-sounding wrong one.
• Availability: Able to commit reliably to 40 hours per week for an initial engagement of 2 to 3 months, with a strong possibility of extension.
• Excellent written communication, and the ability to give precise, well-structured written feedback.

About Cincinnatus LLC

Cincinnatus LLC is an enterprise staffing company that partners with leading technology companies to source and employ highly skilled professionals for contingent and contract-based opportunities. Cincinnatus serves as the employer of record for these engagements, providing W-2 employment, payroll, benefits, and compliance, while placing employees directly within client teams to work on high-impact initiatives.

Roles hired through Cincinnatus are not project-based or freelance engagements. They are structured, role-based positions that typically involve part-time or full-time commitments, close collaboration with a client's internal teams, and integration into standard enterprise workflows.

Cincinnatus is a legal entity separate from Mercor. While opportunities may be discovered through Mercor's platform, employment, onboarding, payroll, and benefits for these roles are administered by Cincinnatus LLC.

Equal Employment Opportunity

Cincinnatus is proud to be an Equal Employment Opportunity employer. We do not discriminate based upon race, religion, color, national origin, sex (including pregnancy, childbirth, reproductive health decisions, or related medical conditions), sexual orientation, gender identity, gender expression, age, status as a protected veteran, status as an individual with a disability, genetic information, political views or activity, or any other legally protected characteristic.

Cincinnatus is committed to providing reasonable accommodations for qualified individuals with disabilities and disabled veterans throughout the job application process.

Where you can work

This role is 100% remote, for applicants located in United States.