Fasteners

Thirty-three years among glue, paint and sawdust. A set has to be carried, pushed and fixed in the dark, and if something does not hold, that is not an aesthetic question. A set designer explains why wide-headed flat screws — the ones people call Opel screws — earned a place among her favourites.

The head is formed as if a washer sat under it, except that it is one piece. It bears over a large surface and — the detail rarely mentioned — already grips when only half-tightened, which is exactly what slotted holes and adjustable cladding need. Where the environment is wet, stainless earns its place.

A hardened carbon steel tip welded to a stainless steel body: the bi-metal self-drilling screw drills and fastens in a single operation, with no pre-drilling, while keeping its corrosion resistance at the surface. Why a plain stainless self-drilling screw cannot do the job, and where the bi-metal version pays for itself.

Where would you need “some sort of pop rivets”? Blind rivets were born in aircraft manufacturing, and the name comes from the English Tucker company's brand. How the mandrel upsets the tube, why cold-formed rivets no longer crack, and why NONOX A2 and A4 are the professional choice outdoors.

A field guide to nuts: the standard hex (DIN 934), hand-tightened wing and butterfly nuts, closed cap nuts, flanged and combi nuts that replace a washer, tall and coupling nuts, weld nuts, rivet nuts and their setting tool, screw-in inserts for wood, and press-fit nuts for thin sheet.

How the concrete screw replaced the wall plug: pre-drill, and the carbide tip cuts its own thread into the concrete. Why the hole must be a shade larger than the core diameter, why NONOX A4 belongs outdoors while galvanised stays inside, and the hex, countersunk and stud versions.

Why a releasable joint still needs securing, and the clever elements that do it: spring, nosed and toothed washers, the two-tab locking plate, double nuts, the split pin and castle nut, plastic-insert and all-metal self-locking nuts, and the spring-steel lock nut the Eiffel Tower was assembled with.

Our most widespread NONOX stainless and acid-resistant bolt, with the largest size range, but mind that hex-head lengths are understood without the head. Rolled threads, cold-forged heads, ordering examples, typical fields of application, and a warning about galling between austenitic bolts and nuts of the same grade.

Drilling, thread forming and fastening in one step, even into stainless sheet. The bi-metal NONOX self-tapping screw pairs an A2 stainless body with a friction-welded hardened steel point that forms the thread without cutting chips, giving 50% more holding force and needing fewer fixing points.