GRBL 1.1 delays when changing direction

[hannozero]

Hello guys,
i’m new to lightburn but i’m learning everydays something new
i fitted my neje 30w laser on a queenbee pro cnc router that i just built, i’m using GRBL 1.1H and arduino uno board and with lightburn 1.0.0.1 i have the following problem:

everything is working fine except that when i change direction i always get some delay, so that if i fill a square this will result skewed, if i run different vertical line in one row from left to right and in the following row from right to left the lines start to be offset and this offset is increasing as i go furter with the pattern (first line is aligned the second a little shifted the third a little more and so on…).
i tryed also to change to 90° the orientation of the pattern and as expected i have the same problem on the y axis, same kind of shift as for the x axis!
-same problem everywhere in the bed so i don’t think that is a bad spot on the linear rail-

now: i check for mechanical issues but everything is tight and running correctly. i measured backlash and i have 0.01mm on the x and 0.02mm on the y so nothing too bad.
already tryed to change pwm edge from the grbl command $2, i tried all the possible combinations but nothing changes
i read the post regarding the skewed squares

How do I fix skewed or slanted engraving?

This is an example of a fill followed by a cut around the letter A: [image] The fill is slanted, but the cut appears to be correct. If you have engraving that is slanting to one side, but cuts appear correctly, you likely have your motor pulse step polarity set incorrectly. On Ruida controllers, there’s a setting called ‘PWM Rising Edge Valid’ that you can change for each axis that tells the controller whether the rising edge or falling edge of a step pulse is what the motor driver is lookin…

and i know that should be a pwm edge problem but unfortunatly changing in grbl this setting $2 didn’t solve the issue.

so i tryed to run the same test of both rows from left to right (without changing direction) and is perfectly aligned. Same thing if i try to fill a square disabling the both ways option, the square will be correct!

is there any other settings that i should try to change in grbl ???

i will try to use another arduino board but i really doubt that this will solve the problem.

is it possible that so little backlash is causing a visible misalignment visible by eyes in 10cm??

please help me cause i’m really frustrated with this issue !!!

many thanks in advance