A locket that closes with a soft, definite click is doing something quietly difficult. Inside that lid are three short lengths of tube, a wire and a groove — nothing more. This is the classic tube hinge, and once you can make one, boxes, bangles and lockets all open up. Here is the sequence.
What chenier is — and why the wall matters
Chenier is the jeweller's word for thin-walled tube, usually drawn seamless in sterling or gold with a wall of around 0.3–0.5 mm. Cut into short lengths it becomes the knuckles of a hinge; a wire through the middle becomes the pin. The same construction, scaled up, carries a box lid or a hinged bangle — only the diameter changes. For a first attempt, work in sterling at 2–2.5 mm outside diameter: large enough to handle, small enough to look right on a locket. Buy tube and pin wire together so the fit is snug from the start — the wire should slide through with light friction, not rattle. Check both with digital callipers from our measuring & marking range before you commit; a pin that is loose in the bore will never make a crisp action, whatever you do later.
Cutting knuckles square
A three-knuckle hinge needs three pieces of chenier of identical length, each end dead square. This is the whole game: square ends make a tight hinge — every out-of-true end becomes a gap, and every gap becomes wobble in the finished lid. Hold the tube in a mitre jig with a chenier cutting vice and saw against the hardened guide face — a fine blade, 6/0 or 8/0, in a jeweller's saw frame is right for thin wall. If your sawing is rusty, our primer on using a jeweller's saw covers blade choice and tension. After sawing, leave each knuckle in the jig and dress the end flat with a fine file until it is truly perpendicular, then clear the burr from the bore with a twist of a fine broach so the pin runs free.
Filing the bearing groove
The two halves of a box or locket meet along a seam, and each half needs a half-round channel — the bearing — filed along that seam so the knuckles sit half-buried between them. A round or half-round needle file cuts the groove; a diamond needle file set gives you the shapes to rough it in and true it up. Work slowly and keep offering up a length of scrap tube: the aim is a groove in each half that together wraps most of the way round the chenier, with the seam falling on the hinge's centre line. If the groove wanders, the lid will sit skewed no matter how well you solder. For keeping filed surfaces flat and consistent, see needle files explained and our notes on filing clean edges.
Soldering the knuckles without freezing the hinge
Knuckle placement alternates. The outer two knuckles are soldered to one half and the centre knuckle to the other — the 2+1 pattern that lets the lid swing. Assemble the whole hinge on a length of steel wire first: solder will not wet steel, and the wire holds all three knuckles in perfect line while you work. Paint anti-flux — typist's correction fluid, rouge mixed to a paste, or a soft pencil line — on the end faces between knuckles and anywhere solder must not travel. Flux only the contact lines, place small pallions, and bring the whole assembly up to temperature gently. Heat the sheet, not the knuckles: chenier is thin and reaches temperature long before the box wall, and a lingering flame will flood solder through the joint and freeze the hinge solid. Fine-tipped tweezers or snipe-nose pliers from our pliers & cutters range make placing a pallion on a 2 mm knuckle far less fraught. If solder control is the weak link, work through soldering sterling silver without pitting and our guide to flux, solder & firebricks before you attempt a hinge.
Fitting the pin and easing the action
Once both halves carry their knuckles, withdraw the steel assembly wire, pickle, rinse and dry. The working pin is a length of matching round wire, traditionally filed with the faintest taper, pushed home with light friction. Test the swing before committing: the lid should move smoothly, with just enough resistance to hold its position. A slightly stiff hinge is the correct result — ease it by working the lid back and forth, or with a light pass of a cutting broach through the bore. A slack hinge cannot be eased; it means the knuckle ends were not square, and the honest fix is to cut three new knuckles rather than live with the rattle. When the action is right, trim the pin a whisker proud at each end and rivet it over with one light tap, or leave it friction-fit on a piece you may want to service later. Keep polishing buffs away from the knuckle line — compound packed into the bearing is the quickest way to spoil a clean action.
Chenier work rewards patient measuring more than any other job at the bench. Browse our measuring & marking tools to get the fit right before the flame comes anywhere near it.