Curious: If you turn a stepper manually can the arduino tell?

I ask because I’m wondering if it’s possible to trace the outline of a piece of wood and have those coordinates sent back to a pc and drawn up or saved as gcode.

Nope

Not the way it’s wired. They generate current, which ends up as voltage, but isnt easy to measure as voltage. I dont know if it would end up as a sinusoid or not. That is interesting… There may not be many machines that are capable of tracing and carving since a lot of them use threaded rods for driving. On the MPCNC, you would have to measure both sides of each axis.

You coupd use encoders attached to each motor instead.

… Googling steppers used as encoders…

https://wemakethings.net/2013/02/18/steppers-as-rotary-encoders/

Holy cow! Someone has done it. So, you’d have to swap the wires each time, write the areuino software, and probably some PC software to accumulate the encoder pulses, then write some software to at leastake an svg out of that. Not too much trouble, really. Sounds like a cool project. They would have the two coils out of phase too, so it would be a quadrature encoder. That would be pretty accurate. It wouldn’t have microstepping, but it would have 200 steps/rotation. I wonder if there’s a minimum speed you’d need. Sounds like we need to couple two motors together to learn more!

Wouldn’t it be cleaner to put an interface board between the stepper and the Arduino that then wouldn’t require rewiring? Though it’d actually be much cleaner to just stick an external encoder on the shaft… Maybe with the steppers that have shafts on both sides?

Google cnc probe. Its cool, but not cheap…