Type H/4 Bevelling Tool, No 1.

Bevelling tool designed by the BBC Research Department used to grind sapphire blanks for disc cutting styli.

Sound recording used a needle or ‘stylus’ to cut grooves into a blank 78 rpm record. Steel needles would wear quickly and require regular replacement, often after a single use. The BBC attached sapphire tips to increase the recording time as the harder material was more durable.

Synthetic sapphires were supplied as cylinders. These were attached to the steel stylus and cut to shape by this bevelling machine. Specific shapes were required to cut an accurate groove for recording sound.