Flexshaft work refers to the broad category of jewellery-bench operations performed with a flexible-shaft machine — a suspended electric motor that transmits rotational power to a slim handpiece through a coiled, armoured flexible cable. The handpiece accepts interchangeable collet chucks, typically accepting shank diameters of 3/32 inch (approximately 2.35 mm) or 1/8 inch (approximately 3.17 mm), and can drive an enormous range of rotary attachments: carbide and diamond burs, abrasive wheels, bristle brushes, felt bobs, rubber polishing points, twist drills, and wire wheels. Variable foot-pedal speed control — commonly spanning 500 to 15,000 revolutions per minute or higher on professional units — allows the bench jeweller to move seamlessly between coarse stock removal and fine finishing without changing machines. The flexshaft is, by most accounts, the single most versatile power tool at the jewellery bench, and competence with it underpins stone setting, fabrication, repair, and surface finishing across virtually every jewellery-making tradition practised today.

Anatomy of the Machine

A standard flexshaft system comprises three principal components. The motor, typically rated between 1/6 and 1/5 horsepower for bench use, hangs from a dedicated hanger or a purpose-built stand, keeping the weight off the working hand and allowing the cable to hang in a natural arc. The flexible shaft itself — the component that gives the tool its name — is a tightly wound inner cable rotating inside a protective outer casing; it transmits torque while accommodating the curves and angles that a rigid drive shaft could not. The handpiece is the working end, held like a pencil or a light pen, and it is here that the collet chuck grips the shank of whichever rotary tool is in use. Quick-release handpieces allow tool changes in seconds, a practical necessity when a single setting job may require a round bur, a setting bur, a hart bur, and a polishing point in rapid succession.

Foot-pedal rheostats give the operator continuous, hands-free speed control. This is not merely a convenience: the ability to slow the rotation for delicate engraving or accelerate it for aggressive metal removal — without releasing the workpiece or the handpiece — is central to the tool's precision. Some professional models incorporate torque-sensing circuitry that maintains consistent speed under load, preventing the stalling that can occur when a bur bites into hard metal at low revolutions.

Principal Applications at the Bench

The range of tasks performed with a flexshaft machine is wide enough that most bench jewellers use it for a significant proportion of their working day. The major categories are as follows.

• Drilling. Twist drills mounted in the collet chuck allow clean, controlled drilling through metal, shell, bone, and softer stones. The pencil grip and foot-pedal speed control give far greater tactile feedback than a drill press for small-scale work, though a drill press remains preferable where perpendicularity is critical.
• Bur work and carving. Carbide steel burs — round, cylinder, cone, flame, inverted cone, hart, and bearing burs among others — are used to open seats for stones, carve bezel interiors, create decorative textures, and remove metal from recesses inaccessible to files. Diamond-coated burs extend the same capability to hard stones, ceramics, and glass. The hart bur (a double-cone or lens-shaped profile) is particularly associated with prong setting, where it cuts the precise notch into which a prong tip is seated.
• Stone setting. Flexshaft bur work is preparatory to setting but the machine is also used during setting itself — trimming prongs, opening bezel walls, and, in bright-cut and pavé work, cutting the bright facets around each stone with a graver held in a rotary graver handpiece or with specialised setting burs.
• Grinding and abrasive work. Mounted abrasive wheels, cylinders, and points — in aluminium oxide, silicon carbide, or diamond — refine surfaces, remove firescale, and shape metal in areas where files cannot reach. Rubber abrasive points impregnated with abrasive grit are particularly useful for pre-polishing in recessed areas.
• Polishing and finishing. Felt bobs charged with polishing compounds (tripoli, rouge, or diamond paste), bristle brushes, and muslin wheels bring surfaces to a high lustre inside rings, around stone settings, and in other confined areas where a polishing lathe or barrel polisher cannot reach. This is among the most frequent uses of the flexshaft in a production or repair context.
• Texturing. Wire wheels, steel brushes, and specialised texturing burs create matte, satin, hammered, or granular surface effects. Florentine finishes and other decorative textures can be applied with appropriate bur profiles.

Burs: A Closer Look

The bur is so central to flexshaft work that the two terms are often used almost interchangeably in bench conversation. Burs are manufactured in high-speed steel, tungsten carbide, and diamond-coated variants. Carbide burs hold an edge significantly longer than high-speed steel and are now the standard for professional use in most markets. Diamond burs — steel shanks with a bonded diamond-grit coating — are essential for working on hard stones, glass, and ceramics, and are available in the same range of profiles as metal-cutting burs.

Bur sizes are designated by number (following the standard bur-numbering conventions used by suppliers such as Gesswein and Rio Grande) or by diameter in millimetres, and the range available spans from under 0.5 mm to several millimetres across. Selecting the correct bur profile and size for a given stone's girdle diameter and pavilion angle is a foundational skill in prong and bezel setting; an incorrectly sized seat will result in a stone that rocks, sits too high, or cannot be secured without distorting the metal.

Speed, Technique, and Safety

Running speed is one of the most consequential variables in flexshaft work. Too high a speed generates frictional heat that can anneal metal unintentionally, burn polishing compounds, glaze abrasive wheels, or — critically — crack or damage heat-sensitive gemstones seated nearby. Too low a speed causes burs to chatter and grab rather than cut cleanly. As a general principle, harder materials and finer finishing operations favour lower speeds with lighter pressure, while softer metals and aggressive stock removal tolerate higher speeds. Lubrication — bur lubricant, beeswax, or a dedicated cutting fluid — prolongs bur life and reduces heat in metal-cutting operations.

Safety considerations are straightforward but important. The rotating handpiece demands that long hair, loose sleeves, and dangling jewellery be secured before use. Eye protection is standard, as burs and abrasive wheels can shed fragments at speed. Dust extraction or respiratory protection is advisable when grinding or polishing, particularly with compounds containing silica or when working on materials that produce hazardous dust.

Equipment in the Trade

The dominant professional flexshaft machines in the anglophone jewellery trade are manufactured by Foredom (Blackstone Industries, USA), whose Series TX and SR motors are considered industry standards and are specified in most trade-school curricula. Competitors include Grobet, Gesswein, and various European and Asian manufacturers. Foredom's interchangeable handpiece system — allowing quick substitution of standard, quick-change, and specialised handpieces on the same motor — has contributed significantly to the machine's adoption as a universal bench tool.

In recent years, compact micromotor handpieces — self-contained units with the motor built directly into the handpiece body — have gained ground, particularly for very fine detail work, engraving, and wax carving, where their lighter weight and reduced vibration offer advantages. However, the traditional hanging-motor flexshaft retains dominance for general bench use owing to its torque, its wide speed range, and the maturity of its accessory ecosystem.

In Education and Training

Flexshaft operation is introduced early in formal jewellery-making programmes — at institutions such as the Gemological Institute of America's jewellery arts courses, the Birmingham School of Jewellery, and comparable trade schools worldwide — because proficiency with the tool is prerequisite to most subsequent bench skills. Students typically begin with basic drilling and bur exercises in copper or brass before progressing to setting operations in precious metal. The tool's learning curve is moderate: basic operations are accessible within hours, but the nuanced pressure, speed, and angle control required for clean setting cuts or fine polishing in recessed areas develops over months of practice.

Further Reading

• Gems & Gemology — GIA's peer-reviewed journal (gia.edu)
• Foredom Electric Co. — product and technique resources (foredom.net)