There were, in effect, two stages in machine making, indeed two types of machine, which might be regarded as primary and secondary. The steam engine, as developed by Newcomen and later, Watt, was a primary machine designed to carry out a specific function – initially to pump water out of a mine.
Early steam engine making was the province of the millwright whose skills, developed over centuries in the building of windmills and watermills, were the most appropriate ones available. A Newcomen engine, built into a brick or masonry engine house, using a massive timber beam as the link between steam cylinder and pump rods, was generally speaking within the already-existing capacities of the millwright.
In 1774 when John Wilkinson, the celebrated ironmaster, patented his boring mill, initially used for guns but soon after for steam engine cylinders, he was making a major contribution to the efficiency of the steam engine… This boring mill was at least as important in the development of the steam engine as any of Watt’s specific and recognized improvements. Indeed the double-acting engine, depending as it did on a closed cylinder with a stuffing box around the piston rod, could not have been made without an accurately machined bore, and that could only be achieved on a boring mill.
– Neil Cossons, ‘The BP Book of Industrial Archeology’ 1987. p131