The flex shaft — sometimes called a pendant drill, grinder, or overhead motor — is a motorised machine built to assist with drilling, polishing, cutting, carving and the like. It is, in the course book's judgement, probably the single most revolutionary multi-purpose tool for the contemporary jeweller. The name describes the architecture:
- a hanging motor — mounted above and behind the bench;
- a hand-piece — the part you hold, where the work happens;
- a flexible shaft connecting the two;
- a foot pedal, operated like a sewing machine's, controlling the speed.
These usually arrive as one kit, supplemented by a myriad of drill bits, mandrels, discs, wheels and burrs — the head components that affix to the hand-piece with a chuck key. Together they create a rapid spinning motion that makes short work of most drilling, carving, polishing and burring tasks.
Why it changed the bench
Every hand technique the flex shaft serves — drilling by bow or hand drill, polishing by cloth, burring by hand-crank — predates it. What the machine adds is sustained, controllable rotation: speed from the pedal, force from the motor, precision from the hand-piece. A split mandrel with sandpaper, a felt disc with compound, a burr, a drill bit — each turns minutes of hand labour into seconds of guided contact, which is why the previous article on finishing could treat motorised sanding and buffing as standard practice.
The three bench rules
The course book attaches exactly three cautions to the machine — and they are all about discipline, not danger theatre:
- Always return the flex shaft to its mount when not in use — never leave it hanging loosely on the bench top.
- Insert head components straight and well-secured before starting the motor — a loosely chucked burr at speed is a projectile.
- Keep the chuck key in a designated drawer between uses — the one tool that stops everything when it goes missing.
Mastery of the flex shaft is less about technique than familiarity: which head component for which job, what speed for which material, and the muscle memory of pedal control. It repays every hour spent with it in saved bench time — which is exactly what a revolutionary tool is for.
Grounded in the JDMIS Metalsmithing (MS100) course materials. Work with the full motorised toolkit in Foundation Metalwork Skills and Creative Silver Modelling Techniques. Related reading: Achieving a Professional Jewellery Finish and Jewellery Files: Cuts, Shapes and Technique.
Frequently asked questions
What is a flex shaft?
A motorised machine — also called a pendant drill, grinder or overhead motor — built from a hanging motor, a hand-piece, a flexible shaft connecting the two and a foot pedal controlling the speed. It assists with drilling, polishing, cutting and carving.
Why is the flex shaft called revolutionary?
It adds sustained, controllable rotation: speed from the pedal, force from the motor, precision from the hand-piece. A split mandrel with sandpaper, a felt disc with compound, a burr or a drill bit each turn minutes of hand labour into seconds of guided contact.
What are the three rules for using a flex shaft?
Always return it to its mount when not in use; insert head components straight and well-secured before starting the motor — a loosely chucked burr at speed is a projectile; and keep the chuck key in a designated drawer, because it is the one tool that stops everything when it goes missing.
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