Large-scale demonstration models for sapphire stylus preparation.
The BBC used a sapphire needle or stylus to both replay records and record sound by cutting onto a disc. Styli would wear and could be strengthened and repaired by attaching sapphire blanks to steel or duralumin shanks. Synthetic sapphire blanks were supplied as cylinders and cut to shape. Using sapphire styli improved the longevity of each stylus needed for the large amount of music and sound output of BBC.
Specific shapes were required to cut an accurate groove for recording sound. These large scale models were produced as demonstration guides for staff training. The models show the three stages of preparation for reproducing the sapphire stylus type RS/8: a sapphire blank (an acrylic cylinder), the sapphire mounted on the steel shank, and the final stylus after the sapphire is ground to shape using a bevelling tool.