Sharpen engraving resolution (x axis)

[yoavkivity]

Hey guys,
I am facing a configuration problem - finding the factor between the motors step value ($100) and the lines per mm(as you can see in the photo) - BUT FOR THE X AXIS!
I am trying to make the engrave more precise (I attached another photo of a inaccurate engraving for x axis).
Do you know how to calculate the ratio of the X axis to get the sharpest result?
thank you!
here is a link to the photos - https://www.facebook.com/groups/lasergrbl/posts/1492486487912009/?comment_id=1493184874508837&reply_comment_id=1493267267833931&notif_id=1673449661459408&notif_t=group_comment_mention