There is a fabled way of checking and setting the headstock alignment of a lathe to the ways which was discussed years ago on various groups that became known as 'Rollies Dads Method'. I can find references to the phrase but not a description of the method - does anyone have a link to the method?
I do remember is was a way of eliminating errors from slightly off centre or bent test bars, and I think it was as simple as averaging reading at both ends but would like to get back to the original source if possible.
AWEM