3D Printed DC Motor

My desire to learn more about actuators started a while ago when I was younger and ever since, you could say that I have developed a bit of an obsession for motors of all shapes and sizes. The simplest electric motor design is a brushed DC motor.

My goal for this project was to learn how to design and build a brushed DC Motor utilizing 3D printing and off the shelf components.

My starting point for this project involved me taking a step back to my college physics courses and remembering what I was taught about electricity and magnetism.

I remember that a current carrying wire creates a magnetic field. And that this magnetic field could be used to induce motion if there was another magnetic field present.

By placing a magnetic magnetic field across the current carrying wire we can use the Lorentz force below to see how the current carrying wire will respond.

F = LI x B

Where L is the length of wire passing through the magnetic field, I is the current (J in the reference image), and B is the magnetic field.

Using the right hand rule (due to the cross product), we can see what direction the wire will want to move.

There is much more involved beyond the scope of this project related to motors, but you have to start somewhere.

The critical aspect of this project that I wanted to tackle was the design related to geometry, material selection, etc. Below I describe my multiple attempts at this effort. Some important requirements I set for myself included: the stator and rotor needed to be designed around 3D printed filament, the motor needed to start freely, any other components needed to be off the shelf items.

Motor Attempt 1

My first motor I was really attempting to achieve the functionality and to have the motor spin. I was not concerned as much with the number of turns or torque/angular velocity output.

The motor did indeed spin but some issues were the lack of torque, the motor did not start automatically, and the brushes did not make the best contact with the commutator ring.

Motor Attempt 2

The second attempt at making my DC motor, I set the goal of improving the self start ability of the motor and improving upon the brushes. I also decided on making the motor larger to incorporate some of these changes and introduce ball bearings to the motor.

The second motor did self start and the brushes were replaced with thicker copper solid core wire which acted more like a spring contact against the commutator ring. Motor torque did improve slightly. The motor did see increased run/test time and as a result I was able to see larger temperature rises across the coils on the rotor.

Motor Attempt 3

For my third attempt, I wanted to attempt to make the motor more compact as well as solve the thermal increase in the rotor coils. Increasing the torque of the motor was also an area of interest during this redesign.

3D Model in FreeCAD

Commutator Ring Made from 1" Copper Tube

Rotor 3D Printed and Wound by Hand

I switched out the 28 gauge wire for 18 gauge magnet wire as the larger diameter wire would reduce the resistance, therefore reducing the amount of energy loss via heat. The motor height was also reduced form 100mm to 60mm. The addition of steel screws in the center of the coil arms were added to increase the permeability of the material which increases the magnetic field generated

The resulting motor below is the final product.

If I were to attempt a fourth DC motor design, I would change the 18 gauge wire for 20 gauge wire for ease of fabrication and greater number of turns. I would also do additional research into other permeable material for the rotor such as electric steel which is the standard for motor construction.

Page updated

Google Sites

Report abuse