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/DMG/ DIY Motor Generation Axial 01/30/2025 (Thu) 11:08:28 No.36271
>Welcome to /DMG/ DIY Motor Generation! This is the place to discuss DIY motor designs, showcase your creations, and refine your ideas on motor tech. This thread is a requested offshoot of the "Actuators For Waifu Movement" thread to focus specifically on DIY motors. We will focus solely on DC motors. I will start the thread off by talking about the types of motors and terms associated with electric motors to keep a good reference to look back on. It should be noted that most motors are Radial Flux and not Axial Flux. What is flux? Magnetic flux is a measure of the total magnetic field which passes through a surface. Radial and Axial describes the orientation of the magnetic flux. Radial Flux Motor > A radial flux motor is like a cylinder spinning inside another cylinder. The magnetic flux flows perpendicular to the axis of rotation, meaning it moves from the stator to the rotor radially outward or inward. Traditional cylindrical motors (like most brushed and brushless DC motors, induction and steppers) are radial flux motors. Rotor and stator are concentric, with the stator surrounding the rotor. Pros: Well-established, widely used, good for high-speed applications. Cons: Can be bulkier and less power-dense compared to axial flux motors. Axial Flux Motor >An axial flux motor is like two discs spinning parallel to each other. The magnetic flux flows parallel to the axis of rotation, meaning it moves along the shaft’s length rather than outward. These motors have a flat, disc-like design where the stator and rotor are stacked on top of each other rather than inside one another. Pros: More compact, higher torque density, and better cooling due to a larger surface area. Cons: More complex to manufacture, higher initial costs. Kinds of Motors: >Brushed DC Motor: Uses brushes and a commutator for current switching. Simple, inexpensive, but requires maintenance due to brush wear. >Brushless DC Motor (BLDC): Uses electronic commutation instead of brushes. More efficient, longer lifespan, commonly used in drones and electric vehicles. >Coreless DC Motor: Lighter and more efficient than traditional brushed motors, often used in small precision devices like robotics and medical instruments. >Stepper Motor: Moves in discrete steps, allowing precise control. Used in CNC machines, 3D printers, and robotics. >Servo Motor: A DC motor with feedback control for precise positioning. Used in robotics, RC vehicles, and automation. >Single-Phase Induction Motor: Used in household appliances like fans and washing machines. >Three-Phase Induction Motor: Used in industrial applications due to high efficiency and reliability. >Linear Motor: Instead of rotating, it moves in a straight line, used in maglev trains and industrial automation. >Switched Reluctance Motor: A highly efficient and durable motor with no magnets, used in electric vehicles and industrial machines. >Universal Motor: Can run on both AC and DC, commonly found in power tools and vacuum cleaners. >Piezoelectric Motor: Uses piezoelectric effect for motion, found in precision instruments and medical devices. >Synchronous Motor: Rotates at the same speed as the supply frequency, used in precision applications. >Hysteresis Motor: A type of synchronous motor with smooth and precise operation, used in clocks and timers. If we analyze all the motor types and configurations here, we can see a single notable design, the Coreless Axial Flux Motor. By combining the Coreless DC Motor with the Axial configuration, we gain significant weight savings and have access to a compact and high power density motor. Further more a Coreless Axial Flux Motor is by far one of the simplest to DIY. Why Coreless? Traditional motors have an iron core in their rotor or stator to guide magnetic fields and improve efficiency. Coreless motors eliminate the iron core, using a winding structure suspended in air or on a non-magnetic support. This results in: Lower weight, Reduced inertia, Lower cogging torque, and Higher efficiency in dynamic applications. Why Axial Flux? Instead of radial magnetic flux, an axial flux motor has flux flowing parallel to the axis. This enables: Compact, disc-shaped designs that save space. Higher torque density, as more of the motor’s active material is utilized effectively. Better cooling, since the large flat surfaces allow for efficient heat dissipation. Coreless Axial Flux Motor - The Ideal DIY Motor? A coreless axial flux design removes both the iron core and the radial structure, making it lightweight, efficient, and easy to manufacture. DIY Advantages: Simpler to build than traditional motors, no need for laminated iron cores. Less material cost. Magnetic layout is easier to DIY, as axial flux motors can be constructed with permanent magnets on a disc rather than wound stators and laminated cores. Ideal for robotics. Potential Downsides: Without an iron core, magnetic flux leakage can be higher, reducing peak efficiency. Requires strong permanent magnets to compensate for the lack of a core. Complex winding design compared to simple cylindrical motors. Despite these trade-offs, coreless axial flux motors are becoming a major DIY motor trend in areas like lightweight drones and robotics. It’s one of the most promising designs for high-efficiency, high-torque applications with a focus on compact, lightweight construction. Axial Flux Motor Configurations: >Single Rotor, Single Stator (SRS) Structure: One stator (copper windings) sandwiched between a single rotor (magnet disc). >Dual Rotor, Single Stator (DRSS) Structure: One stator positioned between two rotors (magnet discs), one on each side. >Dual Stator, Single Rotor (DSSR) Structure: One rotor (magnet disc) positioned between two stators (copper windings). >Dual Rotor, Dual Stator (DRDS) Structure: Two stators with a single rotor in between, similar to DSSR but with an additional rotor. >Multi-Rotor, Multi-Stator (Stacked Configuration) Structure: Multiple stators and rotors stacked in alternating layers. The DRSS Coreless Axial Flux would be the most practical and best choice for maximum power
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In this post I will talk about Stacked PCB Axial Flux Motors. Stacked PCB (Printed Circuit Board) axial flux motors represent a cutting-edge approach to electric motor design. By replacing traditional copper windings with flat PCB traces, they achieve ultra-thin, lightweight, and highly efficient motors. This technology is gaining popularity in precision robotics, drones, and compact electric vehicles. How Stacked PCB Axial Flux Motors Work: PCB as the Stator: Instead of traditional copper coils wound around an iron core, the stator is made up of multiple layers of PCB, with copper traces forming the motor windings. Flat, planar coils replace bulky wire windings. No iron core, eliminating core losses and cogging torque. Compact and easy to manufacture, as the PCB layers can be precisely fabricated. Permanent Magnet Rotor: The rotor consists of high-strength neodymium magnets arranged in a Halbach array or a standard axial flux configuration. Magnets can be placed on both sides of the stator (Dual Rotor, Single Stator configuration) for higher efficiency. Lightweight materials like plastic, carbon fiber or aluminum can be used to reduce mass. Advantages of Stacked PCB Axial Flux Motors. Ultra-Thin & Lightweight: PCB-based stators are much thinner than traditional copper windings, allowing for extremely compact designs. The lack of an iron core reduces weight dramatically. High Efficiency & Power Density: Lower copper losses due to optimized PCB trace geometry. No iron losses (hysteresis & eddy currents) since there’s no iron core. Higher frequency operation with less heat generation, leading to better performance. Scalability & Automated Manufacturing: PCBs can be precisely manufactured using standard fabrication processes. Multi-layer PCB designs allow for stacking, increasing power output while keeping a thin profile. Easier mass production compared to hand-wound coils. Smooth Operation (No Cogging Torque): Traditional motors with an iron core experience cogging torque, where the rotor "snaps" to preferred positions due to magnetic attraction. PCB axial flux motors have no iron core, so they run silky smooth, which is critical for precision applications like drones, gimbals, and medical robots. Challenges of Stacked PCB Axial Flux Motors. Lower Current-Carrying Capacity: PCB traces have higher resistance than thick copper windings, so current capacity is limited. The solution is to use multiple stacked PCB layers or integrate thicker copper plating for improved performance. Requires Strong Magnets: Since PCB traces are thinner than traditional wire windings, they generate a weaker magnetic field. The solution is to use high-performance neodymium magnets and optimize coil layout. Heat Dissipation: PCB traces have limited thermal conductivity, so heat management can be an issue. The solution is to use thermal vias, heatsinks, or forced air cooling. Stacking PCBs for More Power. To increase performance, multiple PCB layers can be stacked together. >Single-Layer PCB Motor: Very thin and lightweight, but limited power output. Good for micro-robots, precision actuators, and small drones. >Dual-Layer PCB Motor: Two PCB layers increase copper area, improving current capacity. Ideal for higher torque applications like robotic arms. >Multi-Layer PCB Motor (3+ layers stacked): More layers = higher power density without increasing the motor’s footprint. Used in compact high-performance motors for electric bikes, vehicles, and robotics.
Hello, Axial. Welcome! This is a thread that's been long-overdue here on /robowaifu/ . Thanks and looking forward to some great innovations for home-spun actuation motors! Cheers, and have fun! :^) >=== -minor edit
Edited last time by Chobitsu on 01/30/2025 (Thu) 11:54:57.
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Let's go back to the ending of the first post where we found that DRSS Coreless Axial Flux Motors are ideal for DIY Motors. Design Considerations and Formulas for a Dual Rotor, Single Stator (DRSS) Coreless Axial Flux Motor >A Dual-Rotor Single-Stator (DRSS) Coreless Axial Flux Motor offers high efficiency, low weight, and reduced cogging torque due to the absence of an iron core. These characteristics make it ideal for applications requiring smooth operation, high torque-to-weight ratios, and compact designs. Rotor Design Considerations >Dual-Rotor Configuration: Two rotating discs sandwich a stator, which allows for better magnetic flux utilization and a more balanced force distribution. >Magnet Placement: Typically, Halbach arrays or evenly spaced neodymium magnets (NdFeB) improve flux concentration and reduce leakage. >Magnet Shape: Arc-segmented or trapezoidal magnets improve flux distribution. >Magnetic Strength and Type: There are different grades and formulations of magnets. Neodymium values range from N28 up to N55 with a theoretical maximum at N64. >Air Gap: Must be kept minimal to maximize efficiency while maintaining manufacturability and mechanical stability. Stator Design >Coreless Winding: Since there's no iron core, the windings are self-supporting and encapsulated with epoxy or composite materials. >Litz Wire: Used to mitigate eddy current losses, especially at high frequencies. >Back Iron Plate: A thin back iron plate behind the magnets can improve magnetic circuit efficiency while reducing unwanted stray fields. Electromagnetic Considerations >Magnetic Flux Density (B-field): Needs to be optimized for high torque while avoiding saturation in surrounding materials. >Winding Topology: Can be toroidal (wires wrapping around) or pancake-style (flat windings), impacting performance and cooling. >Eddy Current Losses: Reduced due to coreless design, but conductor heating still needs to be managed. Mechanical Considerations >Structural Rigidity: Since there’s no iron core, the stator must be mechanically reinforced to prevent deformation under electromagnetic forces. >Cooling: Coreless designs rely on forced air, liquid cooling, or heat sinks since there's no core to conduct heat away. >Rotor Balancing: Essential to prevent vibrations at high speeds. Efficiency Considerations >Minimized Joule Losses: The dominant losses are resistive (I^2*R losses) in the windings. >Hysteresis & Cogging Torque: Since there's no iron, these are practically eliminated. >Optimal Speed Range: Coreless axial flux motors tend to be optimized for specific RPM ranges, with efficiency dropping at extremely high or low speeds. Key Mathematical Formulas >Magnetic Flux Density (B-field) >Torque Calculation (Lorentz force law or based on the flux linkage) >Power Output >Back EMF >Electrical Frequency >Eddy Current Losses See picture for formulas. I'm not sure how to post mathematical formulas on here. (I had to delete the post because i chopped one of the formulas off) >>36275 Soon, I hope to post some cool stuff like an Axial Flux Motor Calculator and Model Generator in OpenSCAD. They both need some work before posting. But I'll continue to work on them as much as I can. I have the broad strokes already down and working just a bit of refinement is needed. My goal is anyone can enter some design constraints and have a python program search for motor configurations, output graphs and parameters that the OpenSCAD model generator can use to generate real 3d printable models. I included a sneak peek into the analyzer and models. (Yes that OpenSCAD file was generated from the Motor Configuration Analysis!) I'm sure many of you can spot the issues. All in due time!
>>36277 >My goal is anyone can enter some design constraints and have a python program search for motor configurations, output graphs and parameters that the OpenSCAD model generator can use to generate real 3d printable models. That sounds remarkable, Anon. Godspeed! <---> BTW, these are excellent effort-posts so far, Axial. Really pro-tier. Thanks! Cheers, Anon. :^)

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