---
title: 'Senior Mechanical Engineer at Arn Autonomy at Cox Exponential'
canonical: 'https://feeny.ai/job/senior-mechanical-engineer-at-arn-autonomy-cox-exponential-south-san-francisco-eepk3a86ecr0'
type: 'job'
last_seen: '2026-10-19'
---

# Senior Mechanical Engineer at Arn Autonomy at Cox Exponential

- **Company:** Cox Exponential
- **Location:** South San Francisco, CA
- **Employment:** full-time
- **Work type:** onsite
- **Posted:** 2026-10-13
- **Last confirmed live:** 2026-10-19
- **Apply:** https://jobs.gem.com/cox-exponential/am9icG9zdDo3pRu-oSSFDxaVEiweifNv

## Job description

Senior Mechanical Engineer

## About the Company

Arn Autonomy is building autonomous, non-humanoid robotic systems to construct infrastructure in extreme, unstructured environments, starting with next-gen construction job sites. Our vision is to disrupt the $16 trillion global construction industry by pioneering a new Deep Tech philosophy that blends robotics, AI, and systems engineering at the frontier. Our flagship product, GRID, is an autonomous rebar-tying robot deployed with rebar and concrete contractors on live job sites.

## About the Role

We're seeking a Senior Mechanical Engineer to join the team building GRID, our rebar-tying mobile robot, and to mentor colleagues on mechanical and electromechanical design. This is a hands-on, cross-disciplinary role spanning mechanical design, electromechanical integration, prototyping, and system-level testing on real hardware. You'll work on the tying mechanism, gantry, chassis, and powertrain, and partner closely with our software, electrical, and manufacturing teams to turn them into a working, testable robot. As an early hire, you'll help shape how we design, build, and validate hardware for field deployment and higher-volume manufacturing.

## Responsibilities

- Mechanical & Electromechanical Design: Design and specify the mechanisms, gantry, chassis, and actuators for a mobile robot operating in outdoor construction environments. Design for durability, serviceability, and performance across outdoor temperatures, dust, vibration, and weather
- Powertrain Design: Size and select electric motors and gearboxes from vehicle-level requirements such as payload, speed, slope, duty cycle, and torque margins
- Terrain Performance: Analyze and validate how the chassis behaves on uneven ground, including gaps and holes in rebar mats and decks (stability, ground clearance, wheel or track geometry, loads on the frame)
- Electromechanical Integration: Integrate motors, sensors, bearings, cabling, and power transmission into robust, field-ready assemblies, using both off-the-shelf and custom components
- Manufacturing Documentation: Turn 3D models into complete drawing packages for machined parts (GD&T, materials, finishes, inspection requirements), and design parts for 3D printing where appropriate
- Prototyping & Validation: Build and instrument prototypes and test setups. Optimize chassis and structural components for strength and stiffness, and run structural analysis (hand calcs and FEA) on critical load-bearing components to validate designs under real operating conditions
- System-Level Testing & Root Cause Analysis: Plan and run system-level tests on GRID; commission, operate, and troubleshoot mechanical subsystems. Identify likely root causes of system issues and failures, and engage the responsible team to drive resolution
- Cross-Functional Collaboration: Work closely with software, electrical, and manufacturing partners; take ownership of specific design and test tasks and bring your expertise to troubleshoot issues as they arise
- Mentorship & Design Guidance: Mentor and support colleagues on mechanical and electromechanical design, including design reviews and good practice in CAD, drawings, and tolerancing
- Manufacturing Readiness: Lead DFM/DFA efforts for machined, 3D-printed, and welded parts, and build test fixtures and procedures to scale toward field deployment and higher-volume production
- Documentation & IP: Document designs, test procedures, and results for traceability and knowledge sharing; contribute to patent work, including invention disclosures and prior-art review

Required

- 5+ years of professional experience in mechanical engineering, robotics, or electromechanical systems, including shipping real hardware to customers or into the field
- Hands-on experience designing electromechanical assemblies (motors, actuators, gear trains, bearings, sensors, cable routing) for mobile platforms, including sizing electric motors and gearboxes from system requirements such as payload, speed, slope, and duty cycle
- Proficiency with at least two CAD packages (for example CATIA, SolidWorks, Fusion, or similar), with strong GD&T and tolerance-stack fundamentals
- Experience turning 3D models into complete drawing packages for machined parts, plus BOMs, specifications, and engineering change documentation; practical knowledge of CNC machining and 3D printing and when to choose each
- Structural analysis skills: comfortable sizing components by hand calc, knowing when to run FEA, and optimizing structures for strength and stiffness
- Experience taking hardware from prototype through design validation and low-volume production, with strong hands-on prototyping, debugging, and testing skills
- Experience mentoring or guiding less experienced engineers, for example through design reviews or day-to-day technical guidance. Formal management experience is not required This is an in-person role, five days a week, in the San Francisco Bay Area. You must be based in the Bay Area or willing to relocate.

## Preferred

- Experience with mobile or outdoor robotic platforms (AMRs, construction or ag equipment, off-road vehicles), including an understanding of how wheeled or tracked chassis behave over uneven terrain with gaps and holes
- Experience with strength-optimized structures (topology optimization, load path design, high-strength aluminum and steel alloys, composites)
- Experience reading and interpreting patents; named inventor on patents is a plus
- Experience with IP-rated enclosures for outdoor, dusty, or wet environments, and with reliability testing and failure analysis
- Experience owning supplier relationships for machined parts or weldments, and working in a fast-paced, early-stage startup

## Compensation & Benefits

Salary range: $90,000 - $165,000, depending on experience, plus equity. Pay offered may vary depending on multiple individualized factors, including market location, job-related knowledge, skills, and experience. The total compensation package for this position may also include other elements depending on the position offered; details will be provided if you receive an offer of employment. We're a startup moving fast, and being in the room together is how we build.

- Daily lunches
- Flexible PTO
- Kaiser Gold HMO health plan
- Pet Friendly Arn Autonomy is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, gender identity or expression, sexual orientation, national origin, age, disability, veteran status, or any other characteristic protected by applicable law.

## About Cox Exponential

## Company Overview
- **One-liner**: Cox Exponential (CX2) is the early-stage AI venture vehicle for Cox Enterprises, partnering with exceptional entrepreneurs to build breakthrough AI/ML companies.
- **Entity Type**: Private (venture capital / accelerator; part of Cox Enterprises)
- **Headquarters**: Silicon Valley, California, United States (with remote presence and an international outlook)
- **Founded**: 2025
- **Founders**: Founded by technologists with decades of experience leading startups and building AI/ML products; key executives include Managing Partner Radu B. Rusu, General Partners Pantelis Kalogiros, Yukiko Jenkins, and others.

## Core Business
- **Primary industry**: Venture Capital & Private Equity (AI-focused early-stage investing)
- **Target customers**: B2B – exceptional entrepreneurs and early-stage AI companies seeking capital, mentorship, and access to the Cox family of businesses.
- **Mission**: Develop breakthrough technology that helps people flourish and bring firsts to market.

## Products & Services
Cox Exponential does not sell a product; it operates as an investment vehicle. Its main “offering” is its accelerator program and venture partnership:
- **AI Accelerator & Venture Program**: Provides capital, technical mentorship, business planning, code/prototype development, and connection to the Cox Enterprises ecosystem.
- **Portfolio Support**: Invests in and supports portfolio companies such as Spacer Robotics (autonomous rebar-tying robot), TrustMind, TrustFoundry.ai, and others.

## Market Standing
- **Valuation / Funding**: Not publicly disclosed (backed by Cox Enterprises, a large private conglomerate).
- **Key Metric**: Total employees ~20 (as of mid-2026); headcount grew ~144% year-over-year since founding in 2025.
- **Notable Investors / Partners**: Cox Enterprises (parent); key executives from Scale Venture Partners, Fyusion, AGI House, etc.
- **Growth Signals**: Rapid team expansion, active hiring for senior engineering roles (AI infra, robotics, efficient ML), multiple open remote positions.

## Competitive Advantages
- **Cox Enterprises Backing**: Access to the breadth of a Fortune 500 company’s resources, industry connections, and potential pilot customers.
- **Founder-Led by Technologists**: The team comprises experienced AI/ML startup builders, offering hands-on technical guidance to portfolio companies.
- **Global Outlook**: Based in Silicon Valley with an international perspective, attracting talent from the US and Portugal.
- **Early-Stage Focus**: Dedicated to pre-seed and seed AI startups, differentiating from larger, less specialized corporate venture arms.

## Strategic Focus
- **Current priorities**: Scaling the accelerator, expanding portfolio companies, and building in-house AI infrastructure talent to support portfolio needs.
- **Direction for growth**: Deepening ties with Cox business units, investing in frontier AI (LLMs, multimodal models, agentic RL, robotics), and hiring top-tier engineers to work on internal AI platforms and portfolio support.

## Why Work Here
- **Culture**: Early-stage, high-autonomy environment within a stable corporate parent. Employees work on cutting-edge AI challenges across multiple portfolio companies.
- **Remote/Hybrid**: Fully remote workspaces for many roles; some positions require in-office presence in San Francisco (e.g., robotics roles). The company has 8 locations but emphasizes remote flexibility.
- **Notable Perks**: Opportunity to work on diverse AI/ML projects (LLMs, robotics, efficient ML systems), exposure to multiple startups, and a flat hierarchy with direct access to experienced partners.
- **Engineering Culture**: Strong emphasis on technical excellence, with open roles for Founding Engineer (AI Infra), Research Scientist (Efficient ML), Robotics Software Engineer, and Systems Engineer.

## Sources
1. [LinkedIn – Exponential by Cox](https://linkedin.com/company/exponential-by-cox)
2. [Built In – Cox Exponential](https://builtin.com/company/cox-exponential)
3. [Built In – Cox Exponential Jobs](https://builtin.com/company/cox-exponential/jobs)
4. [The Org – Cox Exponential (CX2)](https://theorg.com/org/cox-exponential-cx2)
5. [RemoteFront – Remote Jobs at Cox Exponential](https://www.remotefront.com/companies/Cox%20Exponential)

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