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Mechanical Engineer



San Francisco, CA, USA
Posted on Saturday, December 25, 2021

Our Mission

Petra's mission is to save money, property, and lives by moving utilities underground. The company is developing technology to efficiently and safely bore through any geology. Petra's innovative technology is faster and more efficient than conventional tunneling methods, making small-diameter infrastructure economically viable.

The Role

The Mechanical Engineer will be a part of the product development group, consisting of Robotics, Mechanical Engineering, and Manufacturing. The primary function of this role is to conceptualize, design and oversee the creation and implementation of critical subsystems to system-level requirements (packaging, cost, timeline and reliability).

About you

You are a self-starter and can tackle challenges in a fast paced, high aptitude, technical working environment. You are enthusiastic about showing your work and collaborating with fellow team members. You are able to adapt and develop quick solutions when one is not readily available. You feel a deep sense of ownership for the proper functioning of all of your designs, and an appreciation for the importance of quick concepting, detailed design reviews. You design with cost/time/manufacturing constraints built in to your designs.


  • Design components and subassemblies for our tunneling systems.
  • Oversee and/or perform fabrication/manufacturing, assembly, integration, tested and working to specification.
  • Quickly generate conceptual drawings/CAD to present design directions to solve complex mechanical system problems.
  • Turn conceptual drawings into fully-featured CAD designs, including the creation of detailed engineering drawings that communicate any GD&T and critical-to-function requirements clearly and easily understood.
  • Build and validate all relevant designs both on a subsystem level and in-situ, with an understanding of where/when each type of test is important.
  • Iteration and improvement of implemented designs, working with relevant test and field application teams; integrating their feedback and observed functionality to quickly work through changes critical to functionality.
  • Product mechanical design, with an emphasis on top-level CAD assemblies, integration of hardware subsystems, and design for reliability.
  • Drive full documentation of mechanical design, including BOM, drawings, and procedures.


The ideal candidate will have most, if not all, of these requirements:

  • Mechanical component design, including design for CNC, sheet metal fab, welding, and rapid prototyping techniques.
  • Extensive experience working within tight timelines and working closely with vendors to create designs that are optimized for quick-turn / cost-effective production.
  • Bachelor’s degree in Mechanical Engineering, Mechatronics, Robotics, or related technical field with typically a minimum of 6 years related experience; Master’s degree with a minimum of 4 years related experience.
  • Experience in the design of complex mechanical products and equipment through the full product development cycle from inception through maturity including creating associated documentation (specs, test plans, drawings, etc.).
  • SolidWorks or similar CAD experience with best practices for part design, advanced assemblies, complex configuration management.
  • Skilled in the application of GD&T, manufacturing processes, material selection, structures, mechanisms, and thermal management of complex systems.
  • Hands on experience crafting simple proof-of-concept models.
  • Thorough understanding and use of principles, theories and concepts in mechanical engineering.
  • Strong organizational skills and the ability to work well with cross-functional teams.
  • Ability to effectively communicate concepts and write technical documents.
  • Desire and energy to work in a fast-paced agile environment.

Bonus Skills & Experience

  • Prior experience in working with autonomous systems such as self-driving vehicles, drones, mobile robots, and robotic arms.
  • At least 5 years of post-educational experience working on complex electro-mechanical systems such as industrial, aerospace, automotive or robotics products.
  • Please attach a portfolio of your work when applying.


  • Competitive salary and equity.
  • 401K plan.
  • Employer-sponsored health, dental and vision insurance.
  • Healthy lunch and snacks provided.
  • Monthly cell phone reimbursement.
  • Paid holidays and flexible PTO.
  • Relocation costs negotiable.

Equal Opportunity Employer

Petra is an Equal Opportunity Employer; employment with Petra is governed on the basis of merit, competence and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status.