What would i need to change in the software side/firmware side of ramps 1.4 to use a 25T pulley on each stepper instead of the asked for 16T.
I want to get this working with what i have on hand
It’s been 3 years since I did this for my 3D printer, but somewhere in Marlin there should be a steps/mm number. If I recall correctly you only need to know what your current steps/mm are, what distance you commanded, and the distance you moved.
Then solve (<distance commanded>/<distance moved>)*<current steps/mm> = <new steps/mm>. You are basically adjusting the steps/mm by the percentage your commanded move was off by.
I don’t remember exactly where in Marlin the steps/mm variable (or constant? not sure which) though.
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If your steppers have 200 steps per revolution
and if your drivers are microstepping at 32x microsteps
and if your pulley has 16 teeth
and if you’re using GT2 belts with 2mm per tooth
then you should get:
(32 microsteps / step) * (200 steps / rev) * (1 rev / 16 teeth) * (1 tooth / 2mm) which is 200 steps per mm, which is the default.
For 25 teeth per revolution you will move a greater distance, 25/16ths as far, and steps/mm will be a lower value by 16/25ths. If everything else is standard (check your microstepping), you would have 200*16/25 is 128 steps per mm.
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the microsteps need to be changed in configuration.h, around line 642
#define DEFAULT_AXIS_STEPS_PER_UNIT {
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I believe the default is 16x mircostepping with the config at 100 steps/mm.
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so with the 25t pulley ill lose resolution in whatever i am cutting?
I’ve changed it to (128, 128, 512, 128). going to give it a go.
The z axis (third number) is probably not scaled by the same amount since I doubt you have a 25 tooth pulley on it. Just the first two numbers should need changing. (Fourth is for extruder if you ever do that.)