Microstep issue [SOLVED]

SOLVED - end of this message

hi, I have an ox cnc machine assembled and I’m having issues with both x and y axis. Basically when I run a job like a carving job with small details the machine moves like vibrating... while bigger movements it runs very smooth.

My board is xpro cnc, I’ve changed from version 2 to version 3 thinking there was something wrong. But no real improvement.

I’ve encreased the acceleration up to 500 and realized that only the long movements get better (during the acceleration ramp up before making this change I saw some vibration)

I’ve changed the decay mode from mixed to fast as some post suggested it but no improvements at all.

I’ve encreased the microstep from 8 to 32 but again nothing

what i see is that if i play with UGS, below 0.3 mm jog step, motors don't move unless i reach with multiple steps the 0.3 total. In other world, if i set the step in jog mode as 0.1 mm, I need to hit the step movement 3 times to see motor moves at the third hit, as the board doesnt send any command or the motor is not capable of doing the so small step.

making some calculation, with 20 teeth GT3 pulley means each complete motor revolution correspond 60 mm movement, the motor are 200 steps per revolution so each full step is 60/200 = 0.3 mm exactly. so whatever step below 0.3 seems my motor cannot discretize... during jogging I can accept this but during a carving job where small details have to be carved this is a big issue.

It seems my motors are not capable of work properly with microsteps.

Could someone please help me on this cause I’m getting really crazy!!!

Thanks a lot!!!

———————
SOLUTION:
Talking with Ryan from Ooznest we realized that my xpro cnc board could have wrong printing for decay mode: so I’ve soldered fast when it actually was slow mode. Making the appropriate soldering (thanks to Ryan) and encreasing the voltage from potentiometer to each axis even if it seems already well set (thanks to Gary and JustinTime) solved the issue.

Thanks!!!

 

Hi

here below my grbl settings. just for the sake of completness, I've checked:

* belt tensioning
* motor driver currrent
* drivers cooling (I've installed a huge fan on them)
* encrease the acceleration to quickly go to full speed (these helped a lot, before doing it the x and y axis movement where very annoying)

the issue is recognazible in 2 cases:

* during homing: after x and y home switch are triggered the machine goes away and re-check the position, here it moves by steps, not continuosly and smooth
* during milling operation where small feature has to be carved or milled it moves again very "jerky".

thanks

Micro steps now are set to 1/8
------------------------------------------------------------------

Grbl 1.1f ['$' for help]
>>> $$
$0 = 10 (Step pulse time, microseconds)
$1 = 255 (Step idle delay, milliseconds)
$2 = 0 (Step pulse invert, mask)
$3 = 4 (Step direction invert, mask)
$4 = 1 (Invert step enable pin, boolean)
$5 = 0 (Invert limit pins, boolean)
$6 = 0 (Invert probe pin, boolean)
$10 = 1 (Status report options, mask)
$11 = 0.020 (Junction deviation, millimeters)
$12 = 0.002 (Arc tolerance, millimeters)
$13 = 0 (Report in inches, boolean)
$20 = 1 (Soft limits enable, boolean)
$21 = 1 (Hard limits enable, boolean)
$22 = 1 (Homing cycle enable, boolean)
$23 = 1 (Homing direction invert, mask)
$24 = 25.000 (Homing locate feed rate, mm/min)
$25 = 1000.000 (Homing search seek rate, mm/min)
$26 = 250 (Homing switch debounce delay, milliseconds)
$27 = 1.000 (Homing switch pull-off distance, millimeters)
$30 = 1000 (Maximum spindle speed, RPM)
$31 = 0 (Minimum spindle speed, RPM)
$32 = 0 (Laser-mode enable, boolean)
$100 = 26.667 (X-axis travel resolution, step/mm)
$101 = 26.667 (Y-axis travel resolution, step/mm)
$102 = 200.000 (Z-axis travel resolution, step/mm)
$110 = 2500.000 (X-axis maximum rate, mm/min)
$111 = 2500.000 (Y-axis maximum rate, mm/min)
$112 = 2500.000 (Z-axis maximum rate, mm/min)
$120 = 500.000 (X-axis acceleration, mm/sec^2)
$121 = 500.000 (Y-axis acceleration, mm/sec^2)
$122 = 50.000 (Z-axis acceleration, mm/sec^2)
$130 = 320.000 (X-axis maximum travel, millimeters)
$131 = 525.000 (Y-axis maximum travel, millimeters)
$132 = 68.000 (Z-axis maximum travel, millimeters)

 

Hi,

I’ve checked and wheels seem to be ok.

What is really making me crazy is the jog behavior: setting a jog x and y step of 0.1 mm results in no movements for the first two hits, than the motor move when I hit the third time as it is not able to handle microsteps but only full steps

Here it is a short video
Thanks a lot!!

 

Yes, if I run a job the output is dimensionally correct.

That’s the point, it seems no microsteps implemented.

What could be the reason? What else could I check? This is very frustrating...

Thanks again

 

It should be ok but I’ll check it again. Thanks. I was wondering that could be something current related. The strange thing is that the motors don’t lose (apparently) any step when doing cutting job so I’ve considered that the current settings where ok.

Does anybody know if there is a way to check if drivers are supplying the right voltage and current to the motors while in microstep? I mean: if I jog by 0.1 mm step only when I reach the 0.3 sum I see the movement, if I could check any electric parameters when I first hit for 0.1 mm jog I could maybe debug something... my board is xpro cnc versione 3

Thanks

 

Hi,

I’m using standard stepper motor from openbuilds. I’ve got them in the full mechanical package of the ox cnc.

Motors are not getting hot, so I’ll definitely check if higher current can help

I guess that even if the micro stepping is not working properly the max error I could get on a long travel is below 0.3 mm because 0.3 is the minimum full step resolution so it is not easily recognizable

Can any wiring issue let the motor work fine in full step and not working properly in microsteps?

It would be nice to have an easy way to check if motors are correctly ‘energized’ during a microstep position
Thanks