Semi-tubular rivet
Semi-tubular rivet
Hollow-end rivet for cold-joining jewellery components
A semi-tubular rivet is a small mechanical fastener with a hollow cavity drilled or formed into one end and a solid shank on the other, used in jewellery to cold-join components without solder. The hollow end is flared or peened over the receiving piece to form a head and lock the joint; the solid end provides a pre-formed head or upset shoulder. Semi-tubular rivets are common in hinge construction, bezel attachment to mounts, link-and-bracelet assembly, and any application where the joining metals are dissimilar, the heat of soldering would compromise an existing finish or stone, or the design calls for visible mechanical fastening as a decorative feature.
Construction
Semi-tubular rivets are turned from wire or supplied as ready-made fasteners in gold, silver, platinum, copper, brass, and steel. The hollow end is drilled to a specified depth — typically about half the rivet length — and the cavity wall thickness is calibrated such that the rim flares cleanly under the setting punch without splitting. The solid shank diameter is matched to the drilled receiving holes in the joining components, with a working tolerance of roughly 0.05 mm to allow the rivet to seat without play. Shank lengths are chosen so that material stands proud of the components on both sides by enough to form heads under setting pressure.
Setting technique
The bench worker drills clearance holes through the components to be joined, inserts the rivet, supports the solid head against a steel block or rivet anvil, and flares the hollow end with a setting punch and chasing hammer. The flaring is done in stages — first a centre punch to start the spread, then progressively wider tip diameters to peen the rim into a flat, slightly domed head. Light, controlled blows are essential; heavy strikes split the cavity wall and ruin the rivet. The finished joint should show clean, even peen marks and no daylight between rivet head and component.
Setting a semi-tubular rivet requires materially less force than setting a solid rivet of equivalent diameter, since the hollow form deforms readily under the punch. This is the principal advantage over solid rivets in delicate assemblies, where the higher force required to upset a solid rivet risks distorting thin gold sheet or cracking adjacent stones.
Applications
Standard applications in fine-jewellery production include hinge pin retention on lockets and bracelets, watch-case crystal-bezel attachment in vintage and contemporary work, mokume-gane and mixed-alloy assemblies where solder would discolour the layered metals, and the cold-joining of repairs on antique pieces where heating would compromise enamel, stones, or earlier solder joints. Semi-tubular rivets are also used decoratively in industrial-aesthetic and Arts and Crafts work, where the visible peened head is a designed feature rather than a hidden fastener.
In the trade
Bench workers select between solid rivets, semi-tubular rivets, and threaded fasteners according to the access available, the metals being joined, and the consequences of failure. Semi-tubular rivets are the right choice where soldering is excluded by adjacent stones or finishes, where the joining metals would discolour at solder temperature, or where a serviceable removable joint is required. For repair work on antique jewellery, the choice of rivet form should match the original construction wherever the original is recoverable; substituting modern threaded fasteners for original rivets compromises both authenticity and value.