Is it possible to use the closed loop hack on the servo to use in place of the PBY steppers for a 3 axis cnc?
Edit: newbie, apologies in advance. Didn't get any clarity on the web
Yes.
Perhaps more trouble than it is worth, those servos are cheap junk items.
And not for the faint of heart.
Open the servo and grab an analog signal by connecting to the wiper of the feedback potentiometer that the servo itself uses in its own feedback loop.
The signal will vary between two voltages, one near but not necessary Vcc, the other near but not necessarily the supply voltage.
Actuall the top end is supplied by the IC as Vreg, a regulated voltage to ride over supply voltage transients, droops and noise.
The bottom end is above ground due to the resistor between it and ground.
But the voltage you read can be used to get the current physical deflection.
See
HTH
a7
Thanks, had thought so. Though the maslow guys once made that cnc. Do you think better servos like savox would be workable or the line of thinking itself is wasted of time
The concept is sound, and will be as good as the servo is originally.
But I read carefully and see your intent is to replace steppers with servos. This is outside my experience but I would guess is a Bad Idea.
I was not thinking about your deployment scenario, regular servos operate over a narrow range of angles and usually don't have feedback. Adding it would be as I suggested.
Steppers turn and turn, and if used correctly will be where you told them to go. Because they step.
You could substitute a "continuous rotation servo" to get the infinite range of a stepper, but then you'd need something extra to track position; the electronics act as if the servo is at 90 and angles requested greater than that make the motor turn CW at increasing speed the bigger the difference, and angles requested that are less than 90 make the motor turn CCW at increasing speed. They do not provide any way of knowing how many degrees have been turned.
a7
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