rope groove was machined on the edge. The process of making the pins The pin blanks were forged slightly oversize with a square left on one end. They were turned to size on the circular part in a special lathe. They were given a burnished finish between hardened dies One source says they were then tinned to preserve them from rust. The process of making the metal coaks These were cast in bell-metal and the mould left grease-retaining grooves in the inner bore. One end of the coak had a flange and a loose ring was supplied for the other end, together these parts gave a seating for the rivets which fixed the coak to the sheave. Assembly process The shells were smoothed by hand with a spokeshave and then the sheave and pin assembled. They were stored in the Block Mills and issued as demanded. Significant features These machines utilised several features for the first time which have since become commonplace in machine design. The boring operation indented gauging points in the wooden blocks which the clamps of the later machines used to locate the blocks precisely. This meant that positioning of the block in later processes ensured accurate location in relation to the tool working on it. Several of the machines had cone clutches. Brunel used detachable tool bits held in tool holders very similar to those use now on general purpose lathes. Expanding collet chucks were used to locate the sheaves by gripping the internal bore, during certain operations. Two-jaw gripping chucks were used on some machines. These were precursors of the three-jaw chucks used on lathes today. The morticing machines could be set to stop automatically once the operation was finished. interchangeability of the sheaves and pins was possible, since they were not married to a particular shell. The work-flow is perhaps best described as batch production, because of the range of block sizes demanded. But it was basically a production-line system, nevertheless. This method of working did not catch on in general manufacturing in Britain for many decades, and when it did it was imported from America. The entire system was designed to be worked by labourers and not apprentice-trained craftsmen. Each man was trained to operate two or more machines and could be moved round the plant as required. The manufacture of the block-making machines Brunel's patent specification shows wooden framed machines, which, while