Problems with stepper motors from Aliexpress

A lot of people have reported problems with the stepper motors from Aliexpress.

But before we start let me say this. Most of the problems are mechanical problems.
Make sure you're frame is perpendicular and all axes can move freely without any issues.
Also test if you only have problems in stealth mode or also in normal mode.

Tweaking the motor current setting can do damage to the Einsy board as well as create issues with prints like high TMC temp failures!

Be aware that the Einsy board is only capable of 980mA per stepper motor, while the TMC driver could peak up to 2A.

 If you choose to tweak the settings, you do this on your own risk!

If you still having issues with the motors you can adjust the motor current. Some user reported that they had success by increasing the motor currents in the firmware. So I will show you now how to do it.

Before we start changing values in the firmware, we should figure out what the right values would be.
The easiest way to do this is to use the g-code command M907 which is supported in Prusa Firmware since Version 3.5.0.

Let me explain first how the command works, you can also find more details here.

You can set the motor current for all axis to 500mA with

M907 S500

or for each axis individual, which I strongly recommend.

M906 [E<mA>] [X<mA>] [Y<mA>] [Z<mA>]

The format in M907 command is is E,X,Y,Z !

But what would be good values to start with? Well lets have a look into the Prusa Firmware:

In the Configuration_prusa.h file the motor currents are defined in trinamic registers, not in mA!
The format in the Prusa firmware is X,Y,Z,E !

#define TMC2130_CURRENTS_H {16, 20, 35, 30}  // default holding currents for all axes
#define TMC2130_CURRENTS_R {16, 20, 35, 30}  // default running currents for all axes
#define TMC2130_UNLOAD_CURRENT_R 12  // lowe current for M600 to protect filament sensor 

So we need a table to compare the trinamic registers with mA settings.

mA	trinamic register	note
0	0	doesn't mean current off, lowest current is 1/32 current with vsense low range
30	1
40	2
60	3
90	4
100	5
120	6
130	7
150	8
180	9
190	10
210	11
230	12
240	13
250	13
260	14
280	15
300	16
320	17
340	18
350	19
370	20
390	21
410	22
430	23
450	24
460	25
480	26
500	27
520	28
535	29
N/D	30	extruder default
540	33
560	34
580	35
590	36	farm mode extruder default
610	37
630	38
640	39
660	40
670	41
690	42
710	43
720	44
730	45
760	46
770	47
790	48
810	49
820	50
840	51
850	52
870	53
890	54
900	55
920	56
940	57
950	58
970	59
980	60
1000	61
1020	62
1029	63

So the default for the extruder is 535mA. For the z-Axis it is 580mA, for the x-Axis 300mA and for the y-Axis 370mA.

A G-code command for setting the motor current with default values it would look like this:

M907 E535 X300 Y370 Z580

So now you have a baseline to work you way up, until you don't have any issues anymore.

If you just have a problem with one or two axis you can simply remove the other axis.

For example if you have only issues with the Y and the Z axis your command would look like this:

M907 Y390 Z610

Now add this line to the top of your g-code file that you want to use for testing. Print and check if you still have any issues. You can slowly increase the values until your problem is solved. 

Once you have verified the values for your printer, use the table again to calculate the register settings. 

So in our example the g-code:

M907 Y390 Z610

would translate into:

#define TMC2130_CURRENTS_R {16, 21, 37, 30}  // default running currents for all axes

Now we change the Configuration_prusa.h file and compile our firmware and upload it to the printer. Look at my previous posts how to do that. We just change the running currents, the holding currents should not be a problem.

Then test again if everything is ok. If you still have issues try to figure our the proper values with the M907 command first, before you make changes to the firmware settings.

With the higher motor current you might run into some issues. Maybe you get the TCM diver temp failure for long prints or your stepper motors get really hot. This is why it is important to increase the current setting just to what you really need!