A tapered bar has a spiral groove in its conical surface aS shown in Fig A. 1. The groove, starting at A and ending as B is right-handed and advances uniformlv in the axial direction XX, per unit angular rotation about XX. Draw full size, the elevation of the bar showing the groove in full, all curves being accurately constructed. hidden edges Show 88 mm A 13 mm 13 mm 13 mm DETAIL OF GROOVE TB Fig. A N.B. In order for the groove to retain the same cross- section throughout its length, the inner helices must be constructed on conical surfaces which are parallel to the That is, the apices of the cones do not meet outer cone at the same point. 51 mm 102 mm