Fig. 780.
The centres of mandrels should either have an extra countersink, as at a in [Fig. 779], or else the cut should be recessed as at b, [Fig. 780]. Mandrels are best made of steel hardened and ground up after hardening.
Fig. 781.
Fig. 782.
Fig. 780.
The centres of mandrels should either have an extra countersink, as at a in [Fig. 779], or else the cut should be recessed as at b, [Fig. 780]. Mandrels are best made of steel hardened and ground up after hardening.
Fig. 781.
Fig. 782.