BACKING UP THE SHELL
Backing-up the shells with the metal base, i. e., casting, is done automatically by The Rapid Electrotype Company.
A rotary casting-table with a capacity of ten pans revolves around its axis on a plane that brings each pan immediately below a spout through which the required metal is automatically flowed from the bottom of the metal pot on the tinned shell placed therein. When the required metal backing has been flowed, the table turns to bring the next pan with its shell under the metal-spout. The amount of metal flowed is exactly regulated. As the casting table completes a circuit, the first shell backed up has cooled so that it can be removed to the scrubbing machine.
This method, of course, eliminates the hand-ladling of hot metal from the metal-pot to the casting-table, as is the ordinary practice, and obviates any possibility of the oxidized metal or dross on the surface getting into the casts, besides effecting a marked economy in time and handling. In addition, it casts the plates flat, thereby eliminating about 75 per cent of the finishing, which, of course, means a better printing plate. Three of these machines are used.
The Rapid Electrotype Company developed and built these casting-machines in its own machine shop and owns the patents covering them.