How to Build a Simple DC Motor: Theory, Assembly and Hands-On Guide

Overview

This video demonstrates building a simple DC motor and explains how the commutator and magnetic fields produce rotation. The presenter outlines the core components including the base, stator magnets, rotor with a wound coil, the two commutator plates, and bearings, then shows how applying voltage causes current through the coil to generate a magnetic field. By flipping current at the right times via the commutator and applying Fleming's left-hand rule, the rotor keeps spinning. The tutorial covers winding the rotor coil, fabricating commutator plates, assembling the shaft and bearings, and testing the motor at about 12 V. Design files and printable parts are shared in the description.

Introduction

The video introduces a hands-on project to build a simple direct current DC motor and explains the basic physics behind motor operation. It emphasizes a clear, modular build that can be adapted for different outputs by varying winding turns, magnet strength, and the geometry of the rotor-stator assembly.

Core Principles of DC Motors

The motor operates through the interaction of magnetic fields produced by permanent magnets (the stator) and the current-carrying coil on the rotor. When a voltage is applied to the coil via the two contacts that touch the commutator plates, current flows through the windings, generating a magnetic field that interacts with the static magnets. The result is a torque that causes rotation. The direction and continuity of rotation are governed by how the current is reversed, which is accomplished by the commutator in conjunction with the rotor’s position.

Parts and Design Choices

The presenter details the major parts: the base, the stationary stator with magnets, the rotor with a winding, the shaft supported by bearings, and the commutator plates made from copper pipe. The rotor coil is wound with enamel-coated copper wire to electrically isolate turns and maximize magnetic field when current flows. The magnets are arranged so that like poles repel and opposite poles attract, enabling continuous rotation when current direction is reversed at appropriate times by the commutator.

Winding the Rotor

Winding the rotor coil is a central step. The coil is wound clockwise through the rotor holes, with 400 to 600 turns suggested for strong magnetic fields; the video demonstrates a 600-turn example. Ends are tied through the holes and taped to the rotor frame to secure the windings. After winding, enamel is removed from the coil ends to ensure proper electrical contact with the commutator plates, which are glued to the rotor and tested for continuity to confirm the windings connect between the two plates.

Commutator Plates and Assembly

For the commutator plates the guide uses sections of copper pipe cut lengthwise to create two plates. The rotor windings are connected to these plates, and the plates are aligned to ensure proper contact with a small conductor that bridges the gaps between the two plates. The rotor assembly is then slid onto a shaft, and the supports and bearings are installed to allow smooth rotation. Alignment guidelines help position the commutator plates relative to the coil for correct operation.

Testing and Observations

With a DC power supply (typically around 12 V), the motor is powered and observed to start rotating, with speed increasing as voltage increases. The video notes that the basic design is not a high-torque, high-power motor, but serves as a clear demonstration of DC motor operation. Some sparking on the commutator is observed when the lights are off, which can cause wear over time and should be minimized in practice.

Improvements and Extensions

The presenter invites ideas for improvements and mentions several avenues, such as distributing windings over a larger area between the magnets to improve smoothness, using a commutator to maintain continuous rotation, and reducing sparking through better materials, geometry, or contact methods. Other topics touched on include prior deeper explorations of DC, AC, and stepper motors in related videos, and opportunities to experiment with different magnet types and coil geometries.

Files and Resources

Design files are provided for download so viewers can print parts or adapt the model. The video mentions 3D CAD workflows, material choices for 3D printing, and the practicalities of fabricating rotor components from copper pipe. The description contains links to the files and to a sponsor that offers 3D printing and related manufacturing services.

Takeaways

Key concepts demonstrated include how current in a coil creates a magnetic field, how magnetic interactions generate torque, and how the commutator flips current to prevent the rotor from aligning with a fixed magnetic field. With a few simple parts and careful winding, a functional DC motor can be built and experimented with to explore basic electromechanical principles.