I know these questions have probably been asked multiple times and I have had a look around but I might be missing key words when I search. if there is already Forum responses I can reference that would be awesome as well.
Question One:
I'm not good at maths or working out equations, for the life of me can not interpret how I set the current limit on DRV8825 Motor Controllers
I am using Nema14 - 17HS4401 Stepper Motors
PSU is 12V 8.5Amp and the UNO is powered by Laptop USB.
I understand Positive to the Pot on the motor controller and the negative to GND on the board, I Just don't know the value I'm chasing. I would appreciate any simplified answer for this.
Question Two:
I am not using the stepper motors to build a CNC but I will use all Four Axis. X and Y will Mirror each other and Y and A are cloned and will be mirrored. I am learning as I go and have very basic fundamentals of programming my question is how do I control each motor and how to I govern how far it rotates ? using Arduino IDE, I have used GRBL and proven that they are functioning. what are the basics for defining the ports and then telling them what to do?
Question Three:
I cant find how to calibrate a Stepper motor with out being mounted to something that moves in mm, as I said I'm not using it on a CNC rig so I cant test it mm on Degrees... does anyone know how to calibrate a stepper motor as it is with out being attached to something?
thank you in advance any input will be appreciated.
I do not understand your question. The calibration of a stepper motor is done at the factory by the design of the armature. The physical design defines the number of steps the motor will make in a full 360 degrees.
As far as torque, there is no calibration. There is current that is controlled by your controller at the voltage you are using. That produces movement torque as well as holding torque between steps.
What else are you questioning?
A link to the data sheet for that controller may be helpful. In case it's the current limiting adjustment then follow the instructions in the application notes of the board.
From what I see if you setup a CNC machine you run it through a calibration phase I.e if on the machine you want the unit to move 1mm to the right and you measure and it actually travelled say 1.6mm then you can use a formula to adjust for the discrepancy.
Some motors have +-10% accuracy so you can account for it.
My issue is I don’t have a way of making something move left or right I only have the ability to move an object around the spindle so I need to use degrees not mm.
I attached it above, is the link broken?
I can get the information needed for the formula i just don’t how to calculate the formula everything I read tells
Me the formula but I don’t know where to enter the values
Just to repeat you don't need to calibrate! For all intents and purposes a 200 step per rev motor will move 1.8 degrees per input pulse (for unity microstep ratio) as closely as you would be able to measure it.
As you can see from my very detailed drawing, some imagination is needed.
Imagine a piece of rectangle material with 2 steppers motors mounted on the long side, mounted on the under side attached, both following the same movement.
attached to the stepper motor is an 'arm' and the other side is a roller for it to roll freely along the surface.
this will either be self explanatory or open a can of worms.
i see. it really needs no calibration. just 50 steps times microstepping(probably 16) value equals 90 degree rotation. but at the end of moving area it must be some fixation to hold the arm when stepper disabled.
