Question

What do you mean by zero error? Explain the different types of zero errors.

Answer 1

If on bringing the flat end of the screw in contact with the stud, the zero mark of the circular scale coincides with the zero mark on the base line of the main scale, the instrument is said to be free from zero error. Otherwise, an error is said to be there. This can be both positive and negative zero error. This must be accounted for while making calculations. When the plane surface of the screw and the opposite plane stud on the frame are brought into contact, if the zero of the head scale lies below the pitch scale axis, the zero error is positive. If it lies above, then the zero error is negative.