Precision and power are crucial considerations for CNC projects. Using 4 wire brushless motors is one way to improve both of these features. These motors are well-liked by both enthusiasts and professionals due to their small size and high power output.
Our CNC Build Club recently started working on a project that included a small spindle driven by a Brushless DC Hobby motor. The main objective was to enable smooth spindle speed control via GCode commands, improving the CNC machine’s overall functionality.
A unique 3 phase controller is needed to efficiently power the brushless motor. These controllers require a special interface because, unlike conventional spindle motors, they function like hobby servos. We chose RepRap firmware, particularly Marlin because of its built-in servo control features, because our CNC machine uses a delta configuration.
The chosen Brushless DC motor came from Turnigy Track Star and had features like sealed construction, air cooling, and an amazing power rating of 550W, which is equivalent to over 2/3 horsepower. Such qualities make it a perfect match for challenging CNC jobs that demand dependability and performance.
The use of a Brushless Electronic Speed Control (BESC), more specifically the Turnigy Plush 30A model, helped to regulate the motor. This BESC has notable features like a battery eliminator circuit for a handy 5V output, removing the need for external power sources for auxiliary components like RF receivers and servos.
The Azteeg X3 controller was chosen for the control unit because it offers the required interface to efficiently manage the brushless motor. Pulse width modulation, a method we used to precisely control the spindle’s speed, is a crucial component of operating hobby servos.
An Arduino setup was used to manually control the motor during the first testing phase. We were able to implement basic speed control functionality by modifying the “Servo…Knob” example within the Arduino IDE to fit our pin configurations. A crucial change involved switching from traditional pulse control techniques to writeMicroseconds for better accuracy.
The motor’s startup sequence was then semi-automated, streamlining the process and improving user convenience. We were able to successfully optimize the motor’s initialization routine for flawless operation by fine-tuning the Arduino code and adding time – based functions.
Integrating the heater control circuit to control power output was critical in addition to servo speed control. In order to meet the BESC’s specifications and guarantee harmonious operation between the motor and control system, the Marlin firmware had to undergo some modifications.
Although it was initially difficult to match the heater circuit with the BESC’s power control mechanism, a fresh approach using an automotive relay turned out to be quite helpful in properly addressing the problem. We were able to create a strong and dependable setup for flawless motor control by modifying and improving the control circuit.
In conclusion, the use of 4 wire brushless motors in CNC applications offers a variety of benefits, from small form factors to high power output. CNC enthusiasts can achieve improved precision and performance in their projects by utilizing these cutting-edge motors in conjunction with smart control systems, opening the door for creative ideas and effective digital fabrication techniques.
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