Hello, I have tried three different stepper motors and none can move my focus train. I built the DRV8825 HW203 version using my own circuit board with the myFP2F_DRV8825HW203_330 firmware.
First I tried a MY14HY7-1 stepper motor 1.8° 50 mNm, 0.40A; then an Adafruit NEMA-17, 200 steps/revs, 350mA. And finally a NEMA 17, 1.6A, high torque, knowing the amps were too high.
My scope is a William Optics Zenithstar ED80II. All the stepper motors could not move my train and seem to have too little torque for that.
Am I doing something wrong or are these stepper motors not powerful enough?
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That really depends on the configuration and load.
A geared stepper motor significantly increases the ability to move heavy loads.
All your motors are not geared
General rule:
If using a non geared motor, no belts, direct connect, it is likely unable to move a focuing train, esp when pointed to the Zenith.
Even worse:
If you try to increase steps using microstepping, the available torque drops significantly, meaning that if microstepped, it wont even move light imaging trains.
In focuser basics pdf it talks about these issuesm also covered in the main pdf. The calculations are important because they help the decisions aroud motor choice. What you need to aim for is about 10 steps in the CFZ, and use that as a basis for running the motor at Full steps. If you run the motor at full steps, there is no need to set Coil Power On. Which means the motor runs cooler as well
Test1
Set full steps. Place tube parallel to the ground. Make sure 12V is on. Start windows app. true to move in-out using the 100 step button.
If focuser moved : try again with telescope raised to 45 degrees in the sky. Repeat test
If focuser did not move or was very sluggish: Whatever you do, the motor is not powerful enough. Using a geared belt in place of the direct connect then you get a small imcrease in torque but you are still on the losing side. The real answer is to get a geared motor.
Setting Coil Power On or OFF will not make any difference to torque.
Coil Power ON should only be used in microstepped motors.
Regards
Robert
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Hello, I have tried three different stepper motors and none can move my focus train. I built the DRV8825 HW203 version using my own circuit board with the myFP2F_DRV8825HW203_330 firmware.
First I tried a MY14HY7-1 stepper motor 1.8° 50 mNm, 0.40A; then an Adafruit NEMA-17, 200 steps/revs, 350mA. And finally a NEMA 17, 1.6A, high torque, knowing the amps were too high.
My scope is a William Optics Zenithstar ED80II. All the stepper motors could not move my train and seem to have too little torque for that.
Am I doing something wrong or are these stepper motors not powerful enough?
Translated with DeepL.com (free version)
Hi David
Apologies - this thread I missed
That really depends on the configuration and load.
A geared stepper motor significantly increases the ability to move heavy loads.
All your motors are not geared
General rule:
If using a non geared motor, no belts, direct connect, it is likely unable to move a focuing train, esp when pointed to the Zenith.
Even worse:
If you try to increase steps using microstepping, the available torque drops significantly, meaning that if microstepped, it wont even move light imaging trains.
In focuser basics pdf it talks about these issuesm also covered in the main pdf. The calculations are important because they help the decisions aroud motor choice. What you need to aim for is about 10 steps in the CFZ, and use that as a basis for running the motor at Full steps. If you run the motor at full steps, there is no need to set Coil Power On. Which means the motor runs cooler as well
Test1
Set full steps. Place tube parallel to the ground. Make sure 12V is on. Start windows app. true to move in-out using the 100 step button.
If focuser moved : try again with telescope raised to 45 degrees in the sky. Repeat test
If focuser did not move or was very sluggish: Whatever you do, the motor is not powerful enough. Using a geared belt in place of the direct connect then you get a small imcrease in torque but you are still on the losing side. The real answer is to get a geared motor.
Setting Coil Power On or OFF will not make any difference to torque.
Coil Power ON should only be used in microstepped motors.
Regards
Robert