Why consider rivets and fasteners?

Welding is brilliant for many jobs, but it demands skill, power, fume extraction, and it is permanent. For small UK workshops, rivets and threaded fasteners let you join sheet metal with hand tools, no hot work, and often no welder’s certificate. They also allow disassembly for maintenance or repair. But they are not a universal substitute. Choosing well means understanding how each joint carries load, how it fails, and what it costs in time and money.

The rivet family: solid, blind and tubular

Solid rivets are the traditional strongest option for sheet metal. In aluminium or steel, they are set with a hammer and bucking bar or a rivet gun. For 1.5mm to 3mm sheet, a 3mm or 4mm solid rivet gives excellent shear strength. Blind rivets (often called pop rivets) are the workshop staple. They are set from one side with a hand tool. Aluminium blind rivets suit aluminium sheet, but their mandrel leaves a small hole, reducing strength. Steel blind rivets are stronger but need a heavy-duty tool. Tubular rivets are for softer materials and low-load applications. For anything structural, use solid rivets or high-strength structural blind rivets.

Bolts, screws and threaded fasteners

Threaded fasteners win on disassembly. A nut and bolt through clearance holes is simple and strong. For sheet metal, you often need a threaded insert: rivet nuts are set with a tool, giving a female thread in thin sheet. Self-clinching fasteners press into sheet and resist rotation. Self-tapping screws into sheet metal are quick but strip easily and are not for repeated assembly. Machine screws with nylon insert lock nuts or a medium-strength threadlocking compound are reliable. For vibration, use nylon insert lock nuts, serrated flange nuts, or a threadlocker. Avoid over-tightening into thin sheet; use washers to spread the load.

Strength: what actually holds

Compare shear and tensile. A 4mm aluminium blind rivet might have a shear strength around 1.5 kN; a 4mm steel blind rivet around 3 kN. A 6mm solid aluminium rivet can exceed 4 kN. An M6 grade 8.8 bolt in shear can carry over 10 kN. But joint design matters more than fastener rating. Load should be in shear, not tension. Use multiple fasteners, spaced at least 3 diameters from edge and 2.5 diameters apart. Sheet thickness: rivet diameter should be at least 2.5 times sheet thickness for good bearing. For bolts, use washers to spread load. A welded joint is often stiffer and stronger in tension, but riveted or bolted joints can be designed to be just as strong in shear.

Disassembly and maintenance

Rivets must be drilled out. Bolts can be undone. That matters for prototypes, access panels, and equipment that needs servicing. Blind rivets leave the mandrel inside, so drilling out is straightforward: use a drill slightly smaller than the rivet body, centre punch, drill the head off. Solid rivets need the head ground or chiselled. Threaded fasteners can be reused if not damaged. Use anti-seize on stainless into aluminium to prevent galling. Consider captive fasteners for panels that come off often. In short: if you might need to take it apart, use threads.

Cost, tools and practical choices

Blind rivets are the cheapest per joint: a few pence each, hand tool under £30. Solid rivets need a gun or hammer and bucking bar, but rivets cost pennies. Bolts and nuts cost more, perhaps 20p to £1 each, plus drilling and tapping time. Rivet nuts need a setting tool (£30–£100) and cost 15–30p each. Self-tapping screws are cheap but risky. For a small workshop, keep a stock of 3.2mm, 4mm and 4.8mm blind rivets in aluminium and steel, M4, M5 and M6 stainless bolts, nylon insert lock nuts, and a few sizes of rivet nuts. Use a pillar drill for accurate holes. Deburr. For dissimilar metals, insulate with a nylon washer or use a sealant to slow galvanic corrosion.

Welding gives a continuous, stiff, permanent joint. Rivets and fasteners give you a mechanical joint that can be stronger in shear, easier to inspect, and reversible. For a bracket that never comes off, weld it if you can. For a prototype enclosure, a removable panel, or a repair on site, reach for rivets or bolts. Match the fastener to the load, the material, and the number of times you need to take it apart. That is practical engineering.