Materials Engineering Department
BS in Materials Engineering
Kathy Chen; Lee McFarland
The objective of this project was to design and create a process for manufacturing replacement glass prisms for the Piedras Blancas lighthouse and several other lighthouses nationwide. The prisms were designed to be in multiple metal arrays spread across the floor of the beacon room (the topmost room of the lighthouses). The prisms functioned to transmit extra, radiant light from the beacon light through the floor of the beacon room and disperse it into the maintenance room below. Using computer aided drafting (CAD) software, an original prism was measured and modeled; the corresponding mold was also modeled. G-codes for controlling the movement of a computer numerically controlled (CNC) mill were created to machine the two halves of the mold. A donated block of graphite was machined according to the developed G-codes. As a proof of concept method for casting these prisms, I used a lampworking setup – consisting of a propane-oxygen torch, the associated hoses, regulators, and tanks, an annealing kiln, and the necessary lampworking tools – to melt one end of a borosilicate glass rod into a large gather of molten glass. I forced this gather into the mold, thereby filling the mold, and allowed the glass to solidify. Then I opened the mold, removed the prism, melted off the extra rod, and flattened the top face of the prism. This method, although suitable for the proof of concept, will not be efficient for casting the needed quantity of prisms due to the additional, time consuming steps required. For producing large quantities of these prisms, suggested future work may involve pouring molten glass into the mold via the use of a crucible.