Senior Mechanical Design Engineer - Metal Structures

Company Overview

Mainspring Energy is revolutionizing power generation with the world’s most flexible and adaptable local power generation technology, the Mainspring Linear Generator. Commercial, industrial, and utility leaders are choosing Mainspring over traditional options like engines, turbines, and fuel cells to quickly and reliably deliver local power for EV charging, commercial facilities, data centers, and grid‑scale operations. The Mainspring Linear Generator is fuel flexible, ramps up and down to meet demand, and utilizes a flameless reaction with near‑zero NOx emissions.

Backed by top‑tier investors including Khosla Ventures, Bill Gates, American Electric Power, Lightrock, and General Catalyst, Mainspring designs, manufactures, and delivers products to customers across the U.S. today and is rapidly scaling for international expansion. Inspired by a vision of an affordable, reliable, net‑zero carbon grid, Mainspring is expanding within the $816B global electricity equipment market.

More information can be found at

• Pragmatic Optimism – Building a new category of world‑class power generation requires ambition, creativity, and practicality to solve problems efficiently.
• Excellence without Ego – We bring expertise and commitment to creating the best customer experience while applying deep technical rigor to building and delivering world‑class products.
• Proactive Collaboration – Our culture of inclusion and respect extends beyond our team to interactions with partners and customers.

The Senior Mechanical Design Engineer will focus on designing sheet metal components and assemblies for the Mainspring Linear Generator. Responsibilities include developing and improving designs, solving DFM challenges, managing vendors, procuring and testing parts, and ensuring high‑quality execution across all phases of product development. The ideal candidate combines technical expertise with a drive to solve complex problems in a collaborative environment.

• Contribute to brainstorming and technical review sessions to develop solutions that improve performance, cost‑efficiency, and reliability of the Linear Generator.
• Take ownership of the design, analysis, testing, and optimization of structural systems, balancing cost, safety, and reliability trade‑offs.
• Apply sheet metal and joint design knowledge to support development of complex assemblies with efficient manufacturing processes.
• Perform FEA analyses by breaking down complex loading conditions into solvable problems to inform design improvements.
• Conduct tolerance stack‑up analysis to support robust and manufacturable designs.
• Use CAD tools to create detailed drawings and 3D models, maintaining accuracy in design and documentation.
• Support procurement, fabrication, and testing of parts, contributing to hands‑on validation and iterative development.
• Collaborate closely with manufacturing, NPI, test, and reliability teams to ensure designs meet performance, manufacturability, and quality goals.
• Interface with vendors and suppliers to support quality manufacturing and timely delivery.
• Participate in DFMEA processes to identify and mitigate potential failure modes.
• Manage tasks and priorities effectively, supporting delivery of key engineering milestones.

• Degree: BS or MS in Mechanical Engineering or a related field from an accredited institution.
  
  Minimum experience:
  
  Senior – BS + 6 years or MS + 5 years.
• Strong knowledge of sheet metal design, manufacturing processes, fastener selection, joint design, coatings, and assembly practices.
• Experience designing for durability under cyclic and thermal loading with awareness of vibration and acoustic challenges.
• Proven track record contributing to complex projects by defining requirements, evaluating trade‑offs, identifying risks, and supporting key decisions.
• Detail‑oriented, with experience generating and reviewing drawings, bills of materials, tolerance stack‑ups, work instructions, and test documentation.
• Proficiency in Solid Works and PDM (or similar CAD version control systems), with experience using FEA and CFD tools such as…