OmArm One: 7-DOF (6+1 Gripper) Robot Arm on Real Ball Bearings – CAD, Firmware, BOM, Build Guide & Game Controller (Parts 1 + 1.5)

Description

What’s included

Part 1 — the arm

• 23 STL files – every printed part, numbered and print-ready
• Bambu Studio project (.3mf) – two print plates with orientation, seams and supports already set (~15 h). 02_base_link_upper is not on the plates yet: print it from its STL file
• STEP assembly + Fusion 360 source (.f3d) – full parametric CAD for your own modifications
• A1 assembly drawing + BOM Excel – ballooned drawing; the BOM item numbers match the balloons 1:1
• Electronics – wiring diagram, Fritzing source and electronics BOM (ESP32 + PCA9685 + 6× DS3240 + SG90)
• ESP32 firmware – web-app control with quintic motion profiles, a safety layer that never moves blind after a reset, sequence editor, PWA served by the arm itself (no app, no cloud, no router)
• Unit tests – motion, command flow and servo-map tests you can run on your PC without hardware
• 90-page PDF build guide – requirements, torque analysis, bearing architecture, 16 assembly steps with images, wiring, first power-up, payload test, troubleshooting and FAQ

Part 1.5 — drive it with a game controller

• Second ESP32 firmware – Bluetooth instead of WiFi: two thumbs move six joints and the gripper, with no PC, no phone and no network in the loop. Same wiring, same electronics, no new parts.
• Velocity control that feels like a machine – dead zone, expo curve, an 80 ms filter and a fixed braking rate, so a joint physically cannot overshoot. Four speed levels plus an analog gas pedal on the trigger.
• Pose sequence stored in flash – record up to 16 poses with one tap, play them in a loop, and they survive a power cut.
• Latching emergency stop – one button freezes the arm and only the resume button releases it. After a power cut the firmware refuses to move at all until a human confirms the position.
• Gamepad mapper tool – desktop app that shows every stick and button live, learns bindings by pressing them, and writes gamepad_config.h into the sketch folder for you.
• Five more PC-side tests – the real firmware headers compiled with g++ and run against the motion core at the firmware’s own 100 Hz and 250 Hz rates.
• 35-page PDF gamepad guide – which controllers work and which cannot, pairing a DualShock 3 step by step, the full control map, the speed model, the safety layer, a bench checklist, troubleshooting and FAQ.

Works with the PlayStation 3 DualShock 3, DualShock 4, DualSense, Xbox One S / Series, Nintendo Switch Pro and most third-party pads. A classic ESP32 (WROOM or WROVER, the one in the Part 1 electronics) is required.

Specifications

• 6 joints + parallel-jaw gripper · 485 mm reach
• 200 g nominal / 250 g maximum payload at a 300 mm radius (payload model at 6 V; the lifts are in the build video)
• Every loaded joint runs on steel ball bearings: 51110 thrust bearing + 6806ZZ in the base, 695ZZ at the pitch joints, 6806ZZ at the forearm roll
• 6× DSSERVO DS3240-180 (36 kg·cm @ 5 V) + 1× SG90 · ESP32 + PCA9685 @ 250 Hz

Watch and read first

• Part 2 is out: the digital twin video and the written guide, showing the arm as a URDF model in RViz and Gazebo
• Game controller video (Part 1.5): YouTube – OmArm One Part 1.5
• Game controller guide (Part 1.5): the blog post
• Build video: YouTube – OmArm One Part 1
• Source code and analysis script (MIT): GitHub – OmArTronics/OmArm-One
• Full written guide: the blog post (free, with every calculation derived)

This package covers Parts 1 and 1.5 of a 5-part series — Part 2 gives the arm a digital twin in ROS 2, Part 3 adds MoveIt 2 motion planning, Part 4 computer vision, Part 5 marker-free grasping.

License

Firmware, tests and tools: MIT. Wiring diagrams: CC BY-SA 3.0 (Fritzing part graphics). CAD, STL, 3MF, drawings, BOM and guides: personal, non-commercial use only; you may print, build and modify them for your own projects, but redistribution, resale or sharing of the files (original or modified) is not permitted.