A handpiece is the detachable, hand-held terminal component of a flexible-shaft rotary tool, connected to the motor unit by a flexible drive cable and accepted into the jeweller's grip during use. It serves as the working interface between the machine's rotational power and the interchangeable cutting, grinding, engraving, or polishing attachments — burs, diamond points, bristle brushes, felt wheels, and drill bits — that are secured within its collet or chuck. In jewellery manufacture and gemstone work, the handpiece is arguably the most tactile and consequential element of the flexible-shaft system, since its weight, balance, and grip diameter directly govern the precision achievable in stone setting, surface finishing, and engraving.

Construction and Collet Systems

Most handpieces consist of a machined steel or aluminium barrel housing a rotating spindle, terminated at the working end by a collet or chuck assembly. The collet — a split, tapered sleeve — closes concentrically around the shank of the inserted attachment when tightened, ensuring true, wobble-free rotation. Standard shank diameters in jewellery work are most commonly 2.35 mm (3/32 inch) and 3.175 mm (1/8 inch), with the smaller size predominating for fine detail work.

Several collet configurations are in common use:

• Screw-tighten collets — the traditional form, tightened by rotating a knurled collar; secure and precise, but slower to change attachments.
• Quick-change collets — a spring-loaded mechanism allowing tool changes with a single push or twist, improving workflow efficiency during multi-stage finishing sequences.
• Jacobs-style chucks — a three-jaw chuck accepting a wider range of shank diameters, favoured when drilling with standard twist drills.

Types and Configurations

Handpieces are manufactured in several distinct profiles suited to different tasks. The standard barrel handpiece is pencil-shaped and well-balanced for general carving and setting work. The right-angle handpiece positions the working tip at 90 degrees to the barrel axis, improving access to recessed areas and facilitating certain polishing operations. The straight handpiece with a longer, slimmer profile is preferred for engraving and fine detail carving where maximum fingertip sensitivity is required.

Weight is a practical consideration: lighter aluminium-bodied handpieces reduce fatigue during extended sessions, while heavier steel versions may offer greater stability for aggressive stock removal. Grip diameter is equally significant — a barrel too wide for the operator's hand reduces tactile feedback and accelerates fatigue.

Role in Gemstone and Jewellery Work

In the context of gemstone setting, the handpiece is used to drive burs that seat stones, cut bearing ledges, and raise prongs or beads. Carbide and high-speed steel burs in ball, cylinder, hart, and bearing-cut profiles are the most common attachments for this purpose. Diamond-coated burrs and grinding points are employed for working directly on hard gemstone material — carving intaglios, correcting girdle irregularities, or preparing cabochons. Polishing sequences typically conclude with rubberised abrasive points, felt bobs charged with polishing compounds, and bristle brushes, all driven through the same handpiece.

Proper maintenance — periodic lubrication of the handpiece's internal bearings with a purpose-made spindle oil, and regular inspection of the collet for wear — is essential to preserve concentricity and extend service life. A worn or unlubricated handpiece introduces vibration and runout that compromises the quality of setting work and risks damaging fragile stones.

In the Trade

The dominant flexible-shaft systems in professional jewellery workshops — notably those manufactured by Foredom and by various European suppliers — use standardised connection fittings, so handpieces from different manufacturers are often interchangeable within the same system. Bench jewellers typically maintain several handpieces configured for different tasks, avoiding the time cost of repeatedly re-chucking attachments mid-operation. The handpiece is considered a consumable-adjacent item: with heavy professional use, collets and bearings wear and are replaced rather than the entire unit being discarded.