#fastener

Bolted-joint torque, preload and stress maths as an API, computed locally and deterministically for ISO metric fasteners. The torque endpoint applies the torque-tension relation T = K·D·F — the tightening torque equals the nut factor times the nominal diameter times the bolt preload — and solves either way: the torque needed for a target preload, or the preload achieved by a given torque, with the nut factor K capturing the lubrication condition (≈0.20 plain, 0.16 plated, 0.12 lubricated). The stressarea endpoint computes the tensile stress area from the thread geometry, As = π/4·(d − 0.9382·P)² — the effective cross-section that carries the load — together with the nominal shank area and, given a proof or yield stress, the proof and yield loads of the bolt. The preload endpoint sets the clamp force as a percentage of the proof load (75 % is the usual target for reusable joints), F = (percent/100)·σproof·As, and returns the resulting tensile stress and, with a diameter and nut factor, the tightening torque. Grade proof stresses for 8.8, 10.9 and 12.9 bolts are documented. Everything is computed locally and deterministically, so it is instant and private. Ideal for mechanical-design, assembly and maintenance tools, torque-spec generation, fastener selection and structural-bolting apps, and engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is bolt tightening and preload mechanics; for thread pitch/lead geometry use a thread API and for bolt-circle hole patterns use a bolt-circle API.

api.oanor.com/bolttorque-api

Screw-thread geometry as an API, computed locally and deterministically for the 60° ISO metric and Unified (UTS) thread form. The pitch endpoint converts between the thread pitch in millimetres and threads per inch (TPI = 25.4 ÷ pitch) and works out the lead — the distance the thread advances in one turn — from the pitch and the number of starts. The dimensions endpoint takes a nominal (major) diameter and a pitch and returns the full set of thread diameters and heights: the fundamental triangle height, the external thread height, the pitch diameter (D − 0.6495·P), the external minor diameter (D − 1.2269·P) and the internal minor diameter (D − 1.0825·P), in both millimetres and inches. The tapdrill endpoint gives the drill size for cutting an internal thread: the standard metric rule of nominal diameter minus pitch (about 75–83% thread), the resulting thread engagement, and — for a target engagement percentage — the matching drill size. Diameters accept millimetres or inches, and threads can be specified by pitch or by TPI. Everything is computed locally and deterministically, so it is instant and private. Ideal for machining and CNC tools, mechanical-design and CAD apps, maker and 3D-printing projects, and hardware and fastener catalogues. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is screw-thread geometry; for the torque to tighten a bolt use a torque API.

api.oanor.com/thread-api

Bolt and fastener torque maths as an API, using the standard short-form relation T = K · D · F — torque equals the nut factor times the bolt diameter times the clamp load (preload). The torque endpoint computes the tightening torque, in newton-metres, foot-pounds, inch-pounds and kilogram-force metres, from the bolt diameter, the target clamp load and a nut factor — given directly or chosen from a condition preset (dry, lubricated, zinc-plated, galvanized, waxed and more). The preload endpoint solves the inverse: the clamp load a given torque produces on a bolt of a given diameter and friction. The convert endpoint converts a torque value between newton-metres, foot-pounds, inch-pounds and kilogram-force metres. Everything is computed locally and deterministically, so it is instant and private. The K·D·F short form is an estimate that depends heavily on friction — it is engineering guidance only, so always follow the manufacturer's torque specification. Ideal for mechanical, automotive and aerospace tools, maker and assembly apps, maintenance and field-service software, and engineering calculators. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is fastener torque; for wire gauge and resistance use a wire-gauge API and for Ohm's law use an electronics API.

api.oanor.com/torque-api