WHETHER a taper attachment is used or not.To turn the taper, the tool T WOULD be moved back a distance x (assuming that an attachment is used) while traversing the length l.In order to illustrate the principle, assume that the tool could be placed as high as point the setting of the attachment remaining before, then the tool would again move back a distance x while traversing the length l, but the larger end would be UNDERSIZED (as shown by the dotted line) if the diameter of the small ends were the same in each case.Of COURSE, if the tool were only slightly above or below the center, the RESULTING error would also be small.