I.ve tried lots of settings in motor tunning, and it worked fine at any speed, and then it did not, again at any speed. When this stalling happens, it does not matter the speed. The z axis for example was set at 100 mm/sec, which is dead slow, and it did the same problems. I.ve tried all speeds up till 3000 mm/sec, even a bit more for x axis, and it had times when it worked smooth, and then the steppers changed their noise, and either behaved like after minute 1.05 in video, when they just stop, or kept running in a jerky manner and made the ballscrew vibrate.
SW4 is off at the moment.

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The supply has like a potentiometer, on the left side of the the DC output terminals, which says +V ADJ. I did not touch that, but reading with a multimeter, I get exacly 60V.
The drivers are DQ860MA, 24-80V, set at the 4.9A Peak, 3.5A RMS option at the moment. The steppers have written on them 5.6A(U). The next driver setting is at 5.7A Peak. They go up to 7.8A Peak.
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As for steps, I.ve tried 800.1600 and 2000 rev/min. It either function ok with any setting or it does not work, no matter the steps.

The cnc worked smooth on and off, and a driver or source problem would be persistent and require fixing right away. It would not allow the cnc to work sometimes. That.s just my thought.

Could you please tell me why you find ..pulsing to slow.. thing to be irrelevant? What is it, or what is the cause of it?