Mechanical design · Production integration

Mechanical design at Zerith Robotics.

I redesigned motor mounts for 3-axis machining and revised a wrist force/torque-sensor interface that was difficult to assemble. I also contributed CAD and drawings to a humanoid neck mechanism with a senior engineer.

Mechanical Engineering Intern | Zerith Robotics | Shenzhen, China | Jul 2025 - Nov 2025

My work

Component geometry, assembly interfaces, and engineering drawings during a mechanical engineering internship.

Production context

Zerith’s humanoid production volume was 200 robots/month.

Completed work

A manufactured motor mount and assembly fit check, wrist-interface revisions, and collaborative neck CAD.

Zerith humanoid robot in the engineering laboratory — Zerith H1 company platform in the engineering lab. My work focused on mechanical components.

Production hardware

Summary

200

Zerith robots/month

5-axis to 3-axis

Motor mount machining

6-axis

Wrist force sensor

3-DOF

Collaborative neck design

My work addressed machining access and assembly fit within Zerith’s humanoid hardware program.

Production requirements

Designing for production volume

Zerith’s production volume was 200 robots/month. That made supplier access and repeatable assembly practical constraints for my component work.

Responsibilities

My role

I redesigned motor mounts and revised the mechanical wrist-sensor interface. I also contributed CAD and engineering drawings to the neck mechanism alongside a senior engineer.

Machining redesign

Motor mount redesign

Making the mount accessible to 3-axis machining

The original mount used a 5-axis machining process because of its recessed features and tool-access constraints. I revised those features for a 3-axis process while retaining the motor mounting interfaces.

Reworked the mount profiles so the required faces could be reached with standard 3-axis CNC tool access.
Checked the revised geometry in the motor assembly to preserve the mating interfaces.
Made the part compatible with suppliers using conventional 3-axis equipment.
The revised bracket was manufactured and assembled with the wheel motor.

CAD model of a revised orange motor mount with machined tool access — **Revised mount geometry** Revised mount CAD with tool access for the 3-axis machining route.

Manufactured aluminum motor mount on a workbench — **Manufactured bracket** Physical part produced from the revised geometry.

Wheel motor installed in the manufactured aluminum motor mount — **Assembly fit check** Wheel motor installed in the manufactured bracket.

Tolerance stack

Wrist force-sensor integration

Six-axis wrist sensing

I revised the mechanical mounting interface for a six-axis wrist force/torque sensor. The mating locating features were overconstrained: manufacturing variation could prevent the parts from seating together. My work addressed the mechanical fit.

Reviewed the mating profiles and dimensions that controlled seating.
Redesigned the interface geometry to reduce sensitivity to accumulated variation.
Updated the interface dimensions and tolerance requirements for review.
Documented the integration change for engineering review.

Physical six-axis wrist force sensor with its mounting flange, electronics, cable, and mating hardware visible on the assembly bench — **Six-axis force sensor** Physical sensor used at the humanoid wrist interface.

Annotated CAD view highlighting the overconstrained wrist force-sensor interface — **Fit failure diagnosis** The marked mating region was the focus of the assembly-fit investigation.

Revised wrist force-sensor interface CAD model with the updated locating surface — **Revised interface** The revised locating surface left room for manufacturing variation.

Dimensioned CAD study of the revised wrist force-sensor interface — **Dimension study** Dimensioned CAD sketch used to review the revised locating profile.

Mechanism design

Thin 3-DOF neck

3-DOF motion in a thin package

I worked with a senior engineer on CAD and drawings for a compact three-degree-of-freedom neck. The mechanism was designed to provide pitch, yaw, and roll within the robot’s head and shoulder envelope.

Contributed to linkage CAD revisions within the packaging envelope.
Reviewed clearances and mating interfaces in the assembly model.
Prepared engineering drawings that captured the mechanism interfaces for engineering review.
Contributed drawings used to support a patent filing.

Exploded CAD view of the Zerith humanoid robot 3-DOF neck linkage and actuator assembly — **Neck linkage record** Exploded assembly view showing the compact pitch, yaw, and roll mechanism.

Exploded engineering drawing of the Zerith humanoid robot neck assembly — **Assembly drawing** Engineering record for the head, linkage, and mounting interfaces.

Zerith H1 upper-body close-up showing the head, shoulders, and compact neck region — **Robot package** Reference view of the robot package the mechanism had to fit.

Design records

Tools and design documentation

SolidWorks Siemens NX Dimensional tolerancing 3-axis CNC Tolerance analysis Engineering drawings

The mount drawing specifies hole locations and dimensional tolerances. The wrist sketch shows the locating-profile dimensions; the neck views show the linkage and actuator arrangement.

Dimensioned engineering drawing of the Zerith humanoid robot motor mount — **Motor-mount drawing excerpt** Mount dimensions and tolerances. This excerpt shows selected views of the part drawing.

Wrist profile dimensions Dimensioned CAD sketch of the wrist locating profile.

Exploded kinematic drawing of the Zerith humanoid robot neck mechanism — **Kinematic assembly** Linkage and actuator arrangement for the thin 3-DOF neck.