What do you mean by Backlash error? How it can be avoided
The space for the play of screw increases with the use or due to wear and tear, such that when the screw is moved by rotating it in some direction, it slips in the nut and does not cover any linear distance for some rotation of the screw head. The error due to this is known as backlash error.
It is avoided by turning the screw always in the same direction.