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MaC Venture Capital
MaC Venture Capital

Lead Prototype Fabricator



San Francisco, CA, USA
Posted on Wednesday, October 19, 2022

Our Mission

Petra's mission is to save money, property, and lives by moving utilities underground. The company is developing a tunneling robot to efficiently and safely bore utility conduits through hard rock. Petra's innovative technology is 10x faster and 1/10th the cost of most conventional tunneling methods, making small-diameter utility infrastructure economically viable.

The Role

The Lead Prototype Fabricator will be a part of the product development group, consisting of Robotics, Engineering, and Manufacturing. The primary function of this role is to bring conceptual ideas to the physical world, leveraging your extensive range of fabrication abilities.

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 are skilled in troubleshooting test set ups and wiring issues. You embody a culture of safety and grow that culture within the organization. Our ideal candidate is highly skilled, self-driven, detail oriented and has demonstrated success working with a team towards a common goal with proven results. If you’re ready to think outside the box and push yourself and those around you to new levels, apply today.


  • Preparation and fabrication of components and assemblies to engineering specifications
  • Welding – TIG, MIG, in a variety of positions and materials
  • Machining – Manual lathe, manual mill, part set up
  • Sheet Metal – program and operate Waterjet, CNC Press Brake, manual sheet metal equipment
  • Read and interpret engineering drawings, weld symbols and GD&T
  • Use various inspection and measurement tools to validate your work
  • Tracking and documentation of fabrication processes and results when necessary
  • Provide feedback to engineers and management on design and process improvement
  • Root cause analysis and problem solving
  • Work as a team by openly collaborating with engineers and fellow team members
  • Maintain shop equipment as required
  • Maintain a clean and organized workspace: keep tools tidy, components labeled, stocked, and organized
  • Work with design engineers to determine fabrication procedures for prototype projects
  • Build and Maintain work instructions for prototype assembly and retrofit projects


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

  • 5+ years of experience in welding (must include TIG and MIG)
  • 5+ years of experience in manual machining (Lathe and Mill)
  • Extensive knowledge and experience with shop tools/machines (drill press, bandsaws, belt sanders, H-Press, Oxy-Acetylene torch, hand tools etc.)
  • Extensive knowledge of sheet metal design and fabrication
  • In depth knowledge of Engineering documents/CAD/Drawings/Weld Symbols
  • Proficiency with measurement tools and inspection
  • Metallurgical knowledge
  • Thrive in a fast paced, constantly evolving environment with tight deadlines
  • Excellent attention to detail
  • Excellent mechanical aptitude
  • Excellent verbal and written communication skills with ability to develop and present technical information
  • Ability to work efficiently and effectively both independently and as a team with minimal supervision
  • Ability to remain positive and focused in demanding and stressful situations
  • Basic experience with common Google Suite applications like Gmail, Sheets, Docs, etc. (and/or Microsoft Office equivalent)
  • Maintains a growth mindset
  • Flexible with ability to work overtime on short notice based on strategic needs of the company
  • Ability to lift 50 lbs

Bonus Skills and Experience

  • Solidworks Proficient
  • 2+ yrs shop lead experience (willing to take on organization of shop)
  • 2+ yrs of prototype/startup shop experience
  • Experience operating and programming Omax Waterjets
  • Forklift experience
  • Ancillary manufacturing/prototyping experience


  • 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.