Interesting, thanks for the link!

BUT

.....Take note, this is for step output spindles, PWM is another matter, this will
still work, but since the number of steps
in speed is dependent on the PWM settings, the end results may be off in a
stepwie fashion if using PWM.....

Manual calibration would be an awesome feature!

Have you tried it???  Notice that it does say it will work(;-)

(;-) TP

I have tried ad it does not work