The benefit of the Duet 2 controller is already known however making it just a little better is easily done by adding closed loop control to the 3D printer. The cheapest alternative to a full blown servo setup is to incorporate a closed loop stepper motor. This will insure that the motors are getting to where the controller commands them to go. Because of the closed loop nature featuring encoder feedback the driver will compensate within some degree if something does quite make position.
Wiring External Stepper Driver
Head over to Duet3D to learn more about wiring an external stepper driver on the Duet 2 Wifi/Ethernet.
ISS23-20 Integrated Servo Motor
- Input Voltage: 24~50VDC(36V Typical)
- Output Current: 4.5A,20KHz,PWM
- Max Pulse Frequency: 200K
Duet 2 ISS23-20 Config
The trickiest part of the setup was getting the configuration correct. Under the M569 T setting insure the values are as follows: T3.5:3.5:6:0 Until set, these values will mislead in a Core XY setup. Displaying as a possible binding issue and not rotating in sync.
As a result repetitive rebuilds to the linear rails, for nothing. Sometimes things that look mechanical in nature are in fact configuration related. What lead me to this was physically marking the CoreXY shafts with a sharpie and commanding each motor to move the same pulses. The results showed over or under stepping from one of the two motors. Also noted were no errors on the drivers indicating an error in positioning. Some of the steps(pulses) must have just been simply not being registered within the driver (timing). The pulses were being received faster than they could be interpreted by the driver.