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Introduction

Today, we will go through a step-by-step assembly of the Keppe motor.

For more details on how the motor works, please take a look at the patent.

List of materials

1. 3D printed parts;
2. 8mm shaft;
3. 2 bearings (22x8x7mm);
4. Approximately 250 grams of enameled copper wire (the thickness will depend on the desired configuration);
5. Neodymium magnets (the size will depend on the desired configuration);
6. 4 screws of 4mm (minimum length 70mm).

3D parts

The image below shows the necessary 3D printed parts:

Here we have a new component: the commutator disk. This piece is necessary for a motor that uses an optical sensor as a commutator.

This commutator disk has 2 pulses of 60 degrees per rotation, meaning the motor is energized for 1/3 of the time (120 degrees).

In future articles, we will discuss in more detail about commutation strategies.

Rotor assembly

1. Place the rotor component on the shaft, between the bearings, and secure it in place using the rotor supports.

2. At this point, the bearings can be permanently fixed. While not necessary, this helps reduce vibration in the rotor.

3. This image shows the rotor mounted on the shaft. The magnets can be placed now.

Stator assembly

4. Place the shaft in one of the parts of the coil support, and then join it with the stator.

5. Close the stator with the other part of the coil support. Use screws to secure the parts together, and if desired, glue the pieces in place.

6. The stator is ready for the coils.

In this model, it is not possible to make adjustments to the rotor after placing the coils, so please ensure that there are no issues that prevent the rotor from spinning freely.

Coils

7. Wind the coils around the stator. The winding direction of the coils will depend on the rotor configuration.

The number of turns in each coil will vary depending on the desired motor configuration.

In the image below, an AWG 28 wire was used. Each side has approximately 1450 turns (600 turns in the smaller coil and 850 turns in the larger coil).

Coil sizing

The wire gauge will determine the working voltage of the motor.

In the tests I have conducted, I have arrived at the following table:

The electrical power consumed by the motor is difficult to calculate, as it involves many variables. I can highlight the following ones:

• Size and strength of the magnets: The larger and stronger the magnets, the lower the electrical consumption.

• Commutation point: The commutation point is critical to the motor's performance. A simple test is to run the motor without a load and observe at which position the electrical consumption is the lowest. Typically, this point is also where the motor rotates at its highest speed.

• Control circuit: The control circuit can also make a difference when building a motor with lower electrical consumption.

In the points mentioned above, I am assuming that lower electrical consumption is desired for the motor. Depending on the application, this may not be the primary factor to consider.

Questions?

If you have any questions, feel free to contact me.