At the same time as building his Wood Mills, Bentham, with his deputy Simon Goodrich, was constructing a Metal Mills complex a little to the north-east. Alongside a smithery were a copper-smelting furnace and refinery, and a steam engine which drove a rolling mill and tilt hammers. These facilities were for recycling the copper sheathing of ships' hulls; additional facilities for iron work were soon added and a millwrights' shop was established nearby. The Wood Mills, Block Mills, Metal Mills and Millwrights' department were all placed under Goodrich's supervision as Mechanist to the Royal Navy.