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Paolo's AR4 build

AR4 robot arm

Built by Paolo Gagge10 chapters
Model
AR4
Status
In progress

The build, step by step

Follow the journey in Community

  1. Chapter 1 · Sep 5, 2026

    PaMiLoCELL #01: Kitting & System Preparation

    During one of my previous hobby projects, assembling and programming the open-source AR4 robotic arm, supported by the Annin Robotics open-source community and AI tools such as ChatGPT and Codex by OpenAI, my perspective gradually moved beyond the robotic arm itself. That experience led me to explore how Robotics, Industrial Automation, Functional Safety and AI Vision can be integrated into a complete robotic system, with potential applications in Production, Quality and HSE. This is the starting point of PaMiLoCELL, the first technical development project within PaMiLoLAB. The first phase is focused on kitting and system preparation: identifying, selecting and organizing the hardware required to build a compact robotic cell around the AR4-MK5. The planned architecture includes: • AR4-MK5 robotic arm • PLC and industrial automation components • Electrical and functional safety system • Overhead camera • RGB-D camera • Controlled LED lighting • AI Vision computing platform • Mechanical enclosure and integration hardware The objective is not simply to assemble individual components, but to progressively integrate them into a complete, documented and functional robotic cell. Next steps will cover mechanical assembly, PLC integration, electrical safety, machine vision and AI-based object handling. PaMiLoLAB

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  2. Chapter 2 · Sep 5, 2026

    #01 Kitting and system preparation

    During one of my previous hobby projects, assembling and programming the open-source AR4 robotic arm, supported by the Annin Robotics open-source community and AI tools such as ChatGPT and Codex by OpenAI, my perspective gradually moved beyond the robotic arm itself. That experience led me to explore how Robotics, Industrial Automation, Functional Safety and AI Vision can be integrated into a complete robotic system, with potential applications in Production, Quality and HSE. This is the starting point of PaMiLoCELL, the first technical development project within PaMiLoLAB. The first phase is focused on kitting and system preparation: identifying, selecting and organizing the hardware required to build a compact robotic cell around the AR4-MK5. The planned architecture includes: • AR4-MK5 robotic arm • PLC and industrial automation components • Electrical and functional safety system • Overhead camera • RGB-D camera • Controlled LED lighting • AI Vision computing platform • Mechanical enclosure and integration hardware The objective is not simply to assemble individual components, but to progressively integrate them into a complete, documented and functional robotic cell. Next steps will cover mechanical assembly, PLC integration, electrical safety, machine vision and AI-based object handling.

  3. Chapter 3 · Sep 5, 2026

    PaMiLoCELL #02: Robotic Cell Preparation & System Architecture

    Following the initial kitting phase, the next step of PaMiLoCELL has been to prepare the physical environment that will progressively host the complete robotic system. The development started from a hand sketch, followed by several iterations and technical discussions supported by ChatGPT, to define a preliminary cell layout integrating: • AR4-MK5 robotic arm • PLC and industrial automation system • Electrical and Safety Panel • Overhead camera • RGB-D camera • Diffuse LED lighting • AI Vision hardware and software The concept then evolved into preliminary mechanical and electrical documentation covering cell layout, component positioning and a first wiring architecture. Current project status Everything is still preliminary and conceptual. The drawings, layouts and wiring architecture are a development trace to guide the next steps. They are not yet fully verified against the final physical configuration and may contain assumptions, inconsistencies or technical errors. That is part of the challenge: study the system, build it step by step, identify what does not work, verify assumptions and correct the design as the real cell develops. The goal is not to present a finished engineering solution, but a structured path where each step can be reviewed, tested and improved. Development sequence: Concept & preliminary layout Initial sketches and system architecture. Cell preparation Mechanical environment and spaces for robot, PLC, Safety Panel and Vision devices. AR4-MK5 installation Robot positioning and verification of real workspace, reachability and clearances. PLC & Safety integration Installation, wiring and verification of automation and safety architecture. AI Vision integration Positioning and calibration of overhead camera, RGB-D camera and controlled lighting. Risk Assessment & Safety Validation Once the AR4-MK5 is installed and the real cell configuration is available, the project will move to: PaMiLoCELL_Risk_Assessment_Safety_Validation_Rev0 This phase will evaluate actual hazards and required safety functions, including robot movements, cell access, emergency stop, interlocks, electrical risks and safety architecture. The project will evolve iteratively: Concept → Build → Verify → Identify Errors → Correct → Integrate → Validate The key point is not to assume the first design is correct, but to use each step to learn, challenge assumptions and progressively improve the system. PaMiLoLAB

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  4. Chapter 4 · Sep 5, 2026

    #02 Robotic cell preparation and system architecture

    Following the initial kitting phase, the next step of PaMiLoCELL has been to prepare the physical environment that will progressively host the complete robotic system. The development started from a hand sketch, followed by several iterations and technical discussions supported by ChatGPT, to define a preliminary cell layout integrating: • AR4-MK5 robotic arm • PLC and industrial automation system • Electrical and Safety Panel • Overhead camera • RGB-D camera • Diffuse LED lighting • AI Vision hardware and software The concept then evolved into preliminary mechanical and electrical documentation covering cell layout, component positioning and a first wiring architecture. Current project status Everything is still preliminary and conceptual. The drawings, layouts and wiring architecture are a development trace to guide the next steps. They are not yet fully verified against the final physical configuration and may contain assumptions, inconsistencies or technical errors. That is part of the challenge: study the system, build it step by step, identify what does not work, verify assumptions and correct the design as the real cell develops. The goal is not to present a finished engineering solution, but a structured path where each step can be reviewed, tested and improved. Development sequence: Concept & preliminary layout Initial sketches and system architecture. Cell preparation Mechanical environment and spaces for robot, PLC, Safety Panel and Vision devices. AR4-MK5 installation Robot positioning and verification of real workspace, reachability and clearances. PLC & Safety integration Installation, wiring and verification of automation and safety architecture. AI Vision integration Positioning and calibration of overhead camera, RGB-D camera and controlled lighting. Risk Assessment & Safety Validation Once the AR4-MK5 is installed and the real cell configuration is available, the project will move to: PaMiLoCELL_Risk_Assessment_Safety_Validation_Rev0 This phase will evaluate actual hazards and required safety functions, including robot movements, cell access, emergency stop, interlocks, electrical risks and safety architecture. The project will evolve iteratively: Concept → Build → Verify → Identify Errors → Correct → Integrate → Validate The key point is not to assume the first design is correct, but to use each step to learn, challenge assumptions and progressively improve the system.

  5. Chapter 5 · Sep 5, 2026

    PaMiLoCELL #03: Tools Are Very Important

    A good assembly also depends on using the right tools for each operation. Some of the equipment being prepared for PaMiLoCELL and AR4-MK5 assembly: • Drill press and rotary/power tools • Soldering and electrical work tools • Precision screwdriver and bit sets • Wire stripper / crimping tool • Digital caliper for dimensional checks • Tweezers and cutting tools • Loctite 222: low-strength threadlocker • Loctite 648: retaining compound for cylindrical parts • Liquid electrical insulation coating • Bearing / bushing / seal installation kit The objective is simple: assemble correctly, measure, verify and avoid damaging components. Right tool → Better assembly → Better reliability PaMiLoLAB

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  6. Chapter 6 · Sep 5, 2026

    #03 Tools for the assembly

    A good assembly also depends on using the right tools for each operation. Some of the equipment being prepared for PaMiLoCELL and AR4-MK5 assembly: • Drill press and rotary/power tools • Soldering and electrical work tools • Precision screwdriver and bit sets • Wire stripper / crimping tool • Digital caliper for dimensional checks • Tweezers and cutting tools • Loctite 222: low-strength threadlocker • Loctite 648: retaining compound for cylindrical parts • Liquid electrical insulation coating • Bearing / bushing / seal installation kit The objective is simple: assemble correctly, measure, verify and avoid damaging components. Right tool → Better assembly → Better reliability

  7. Chapter 7 · Sep 10, 2026

    #04 Stepper motor wiring

    The AR4-MK5 wiring phase is progressing, with particular attention to the J1 stepper motor, digital drivers and control architecture inside the robot’s compact electrical cabinet. The ground floor of the micro-cabinet is dedicated to the digital stepper drivers. Each driver effectively interfaces two different domains: Power side: supplies the controlled phase currents to the stepper motor windings. Correct identification and connection of the motor phases, A+, A−, B+, B−, is essential for proper torque generation and rotation. Command side: receives low-power control signals such as PULSE, DIRECTION and ENABLE from the controller. These signals define when the motor moves, in which direction and whether the driver output stage is enabled. This separation between power wiring and control wiring is an important concept in the robot architecture: the driver acts as the interface between low-power digital commands and the considerably higher motor phase currents. The first floor, immediately above the drivers, is dedicated to the Teensy 4.1 control board. The Teensy is connected to the digital drivers for motion commands, to selected motor feedback/sensor wiring, and will provide the interface toward the external PLC through Modbus RS-485. The resulting control chain can therefore be summarized as: PLC → Modbus RS-485 → Teensy 4.1 → STEP/DIR signals → Digital Drivers → Stepper Motors During assembly, some practical wiring lessons also became clear. Small details can have a significant impact on reliability: When stripping thin conductors, even a small nick in the copper can create a fatigue initiation point, especially where the cable is repeatedly flexed. Moving sections should use stranded / continuous-flex conductors whenever possible, rather than rigid solid-core wires. With screw terminals, the conductor must actually enter between the clamping plates. A wire can appear correctly positioned while remaining outside the clamp. A simple pull test after tightening each terminal is an effective verification step. Ferrules can improve termination quality for very small stranded wires, provided that the correct size is selected. Some encoder conductors available on the J1 motor are not required by the standard AR4 configuration, showing the importance of understanding each signal before cutting or terminating the cable. This phase is not only about completing the wiring. It is also about understanding how power electronics, motion control and communication layers interact inside a compact robotic system. Next step: complete the internal wiring and progressively validate the control chain from Teensy to the motor drivers.

  8. Chapter 8 · Sep 12, 2026

    PaMiLoCELL #05: Motor, Bearing, Gear & Belt Installation

    The AR4-MK5 mechanical assembly is progressing through the main transmission elements: motor, bearings, timing pulleys/gears and belts. I approached this phase from a Quality Engineering perspective, treating each assembly step as a small Quality Gate. Motor: Check fastening, shaft/pulley interface and cable routing. Any misalignment introduced here can later affect belt tracking and bearing loads. Bearings: Tapered roller bearings require different installation methods: - Outer race → aluminium housing: heat the housing uniformly to slightly expand the seat, then press the race squarely into position. Never hammer it. - Inner bearing cone → shaft: warm the bearing/cone assembly to slightly expand the inner ring before fitting it onto the shaft. If force is required, apply it only to the inner ring, never through the rollers. After pressing the outer race, verify seating depth at 0° / 90° / 180° / 270° with a digital caliper. This is a practical QC check of uniform seating and parallelism, while also considering measurement repeatability. Thread locking / retaining compound - LOCTITE 222: low-strength threadlocker for removable threaded fasteners, used on M4 and larger screws as specified by the AR4 manual. - LOCTITE 648: retaining compound for cylindrical fits; use only if an outer race is slightly loose in its housing, not as a general installation aid and not normally between inner ring and shaft. Gear / pulley: Check seating, axial position and pulley alignment. Small offsets can cause belt tracking issues and additional bearing loads. Belt: Tension must prevent backlash and tooth skipping without overloading shafts, bearings or structures. Final QC: Before closing the covers, manually check: smooth rotation, correct belt tracking, no abnormal friction, controlled preload, no excessive play and no interference. The key lesson is that: Motor → Bearing → Gear/Pulley → Belt should also be a sequence of Quality Gates. Detecting an incorrect bearing seat, pulley misalignment or excessive belt tension immediately is far easier than troubleshooting the defect after the robot is fully assembled. #PaMiLoCELL #PaMiLoLAB #AR4MK5 #Robotics #QualityEngineering #RobotAssembly #Bearings #TimingBelt #LessonsLearned

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  9. Chapter 9 · Sep 12, 2026

    #05 Motor, bearing, gear and belt installation

    The AR4-MK5 mechanical assembly is progressing through the main transmission elements: motor, bearings, timing pulleys/gears and belts. I approached this phase from a Quality Engineering perspective, treating each assembly step as a small Quality Gate. Motor: Check fastening, shaft/pulley interface and cable routing. Any misalignment introduced here can later affect belt tracking and bearing loads. Bearings: Tapered roller bearings require different installation methods: - Outer race → aluminium housing: heat the housing uniformly to slightly expand the seat, then press the race squarely into position. Never hammer it. - Inner bearing cone → shaft: warm the bearing/cone assembly to slightly expand the inner ring before fitting it onto the shaft. If force is required, apply it only to the inner ring, never through the rollers. After pressing the outer race, verify seating depth at 0° / 90° / 180° / 270° with a digital caliper. This is a practical QC check of uniform seating and parallelism, while also considering measurement repeatability. Thread locking / retaining compound - LOCTITE 222: low-strength threadlocker for removable threaded fasteners, used on M4 and larger screws as specified by the AR4 manual. - LOCTITE 648: retaining compound for cylindrical fits; use only if an outer race is slightly loose in its housing, not as a general installation aid and not normally between inner ring and shaft. Gear / pulley: Check seating, axial position and pulley alignment. Small offsets can cause belt tracking issues and additional bearing loads. Belt: Tension must prevent backlash and tooth skipping without overloading shafts, bearings or structures. Final QC: Before closing the covers, manually check: smooth rotation, correct belt tracking, no abnormal friction, controlled preload, no excessive play and no interference. The key lesson is that: Motor → Bearing → Gear/Pulley → Belt should also be a sequence of Quality Gates. Detecting an incorrect bearing seat, pulley misalignment or excessive belt tension immediately is far easier than troubleshooting the defect after the robot is fully assembled.

  10. Chapter 10 · Sep 22, 2026

    #06 Shaft, key and fastener assembly

    During the AR4-MK5 assembly and MK4 → MK5 upgrade, one of the most useful lessons came from something apparently simple: fitting a keyed shaft. For those unfamiliar with robot mechanics, J1 and J2 are the first two robot joints. J1 rotates the robot around its base; J2 is the shoulder joint that raises and lowers the arm. During J2 assembly, the 14 mm gearbox shaft with parallel key would not enter its mating hub correctly. The first instinct could be to apply more force. Instead, the problem became a practical troubleshooting exercise: Where is the interference actually coming from? The checks included shaft diameter, key height, keyway alignment, possible burrs and the overall shaft-plus-key dimension measured with a caliper. The key was first pressed fully into its seat using a bench vise with protective tape. When a small residual interference remained, the key was carefully filed in very small increments, repeatedly checking the fit. Only in this kind of exceptional situation, once the geometry and alignment are verified, a soft rubber mallet can help progressively seat the gearbox assembly, never striking the shaft or key directly. Another important lesson came from the AR4 instructions: fully inserted does not mean eliminating every visible gap. When J2 is correctly installed, about 2 mm remains between the gearbox shoulder and the J2 tension ring. The same reasoning applies to bolts and nuts. Fasteners should clamp correctly aligned components, not pull misaligned parts into position. Threads should be started by hand and tightened progressively, using an alternating sequence when several bolts clamp the same flange. The MK4 → MK5 upgrade also reinforced the importance of understanding all locking points, set screws and mounting fasteners before applying extraction or assembly force. Where specified, threadlocker must also be selected correctly: the AR4 instructions recommend low-strength threadlocker for screws 4 mm and larger, but not for 3 mm and smaller screws. A future PaMiLoCELL upgrade will introduce torque wrenches, allowing critical fasteners to be tightened with controlled and repeatable torque rather than relying only on manual feel. The workflow I take from this experience is: inspect → measure → understand → correct → align → seat → tighten Precision assembly is not about applying more force. It is about understanding dimensions, alignment, contact surfaces, interference and clamping forces.

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