On going chinese 6040 problems

[JAZZCNC]

Ok well I think you main problem is coming from the BOB and the fact it will have slow opto isolators. This is why your getting better results using higher step pulse.
Try running in Sherline mode and see how it goes because all thou your set at 10 -15 your not getting that as Mach in normal mode doesn't go that high.? Sherline mode gives you wider step pulse so gives the opto's more time to work. You'll find it in port's n pins on first page near Kernal speed. You'll have to restart Mach3 and retune motors.

To be honest you have several issues here all of which can only be cured with a bullet or a mallet.!! . . . . Crap celectronics give crap results.

With the high inductance motors you have and only 24Vdc running rubbish drives thru a piss poor BOB then in all fairness your near the end of what should be expected. Sell the lot and buy decent drives. Don't go for the G540 as there are better options for less money and the Gecko is restricted to 3A motors to use it's full capabiltys.
Your main issue with slow speed is lack of volts but don't go giving the drives more because you'll fry them. Max they will stand is 36V and they won;t like that for long before letting out magic smoke plus 36v isn't much better than 24V with these motors and you'll need 50V drive running 44-46V to get any decent speed from them.

Now with the stalling and micro stepping then after the short pulse width problem then resonance is the next issue you'll be encountering. Resonance affects motors in differant ways and is often worse when sat on the bench.
Also the micro stepping plays it's part here as well. Setting the Micro steps too near to full Step 1-1 often makes resonance worse so stalls more. Setting higher makes the motors run smoother so less stalling but this comes at the cost of many more pulses required which in your case makes things worse because your Rubbish BOB can't keep up as it is.!!. . . So it's a double edge sword I'm afraid.!! . . . Fubar'd in both cases.!!. . . Time to get Timmy out.!!

This is why decent electronics and the quality of the pulses being sent to the drives/motors is so very important.