What you have is backlash. Since it repeats every time, it's not a skip. Look at things like belt tension and play in the rod ends.
One classic is the belt drive gears slipping back and forth on the stepper shaft because they aren't quite tight enough. If your steppers have flats on the shafts they will slip over a very narrow range. The result will be what you are seeing.
If it was a measurement issue, it would not be directional.
If it was software, everybody on the planet would go nuts about it.
One classic is the belt drive gears slipping back and forth on the stepper shaft because they aren't quite tight enough. If your steppers have flats on the shafts they will slip over a very narrow range. The result will be what you are seeing.
If it was a measurement issue, it would not be directional.
If it was software, everybody on the planet would go nuts about it.