{"uid":"cap_LB5QucRrqFut07vX_sYp6","slug":"machining-fasteners-calc-bolt-torque-fec1e810","name":"Machining & Fasteners Calc – Bolt Torque","description":"Bolt preload (75 percent of proof) and tightening torque estimate T = K F d for ISO property classes 8.8, 10.9, 12.9.","url":"https://machining-calc.x402tookit.com/bolt-torque?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":["diameter","propertyClass"],"properties":{"pitch":{"type":"number","description":"Pitch in mm; omit for the ISO coarse pitch of M3 to M24"},"diameter":{"type":"number","description":"Nominal diameter in mm, 3 to 48"},"nutFactor":{"type":"number","description":"Nut factor K, 0.08 to 0.4 (default 0.2: dry steel; about 0.15 lightly oiled)"},"propertyClass":{"type":"string","description":"8.8, 10.9 or 12.9"},"preloadFraction":{"type":"number","description":"Fraction of proof load to preload to, 0.3 to 0.9 (default 0.75)"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"asOf":{"type":["null","string"]},"source":{"type":["null","string"]},"pitchMm":{"type":["null","number"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"summary":{"type":["null","string"]},"verdict":{"type":["null","string"]},"degraded":{"type":["boolean","null"]},"torqueNm":{"type":["null","number"]},"nutFactor":{"type":["null","number"]},"preloadKN":{"type":["null","number"]},"diameterMm":{"type":["null","number"]},"disclaimer":{"type":["null","string"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"proofLoadKN":{"type":["null","number"]},"torqueLbfFt":{"type":["null","number"]},"propertyClass":{"type":["null","string"]},"stressAreaMm2":{"type":["null","number"]},"proofStressMPa":{"type":["null","number"]},"preloadFraction":{"type":["null","number"]}}}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.02","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.02/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_p6BmOj6VLruNmzPMDwwMw","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.02","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Calculates ISO bolt preload force and tightening torque using T = K·F·d for property classes 8.8, 10.9, and 12.9","exampleAgentPrompt":"What tightening torque and preload force should I use for an M12 class 10.9 bolt with a lightly oiled interface — give me the result in Nm using a nut factor of 0.15 and 75% of proof load.","exampleUseCases":[{"title":"Torque spec for assembly line","prompt":"I'm assembling a steel bracket with M10 class 8.8 bolts using dry steel surfaces. What tightening torque in Nm and lbf·ft should the team use, assuming standard 75% preload?"},{"title":"High-strength joint design check","prompt":"For an M16 property class 12.9 bolt with a lightly oiled interface (nut factor 0.15), what's the preload force in kN and the required tightening torque?"},{"title":"Custom preload fraction for critical joint","prompt":"I need to preload an M20 class 10.9 bolt to only 60% of proof load to stay within yield limits — what torque in Nm does that require, assuming a standard dry steel nut factor?"}],"resultDescription":"Returns tightening torque in both Nm and lbf·ft, preload force in kN, proof load in kN, thread stress area in mm², proof stress in MPa, pitch in mm, the nut factor and preload fraction used, a plain-language summary, and an engineering disclaimer. May also include degraded-mode flags and validation reasons if inputs are at limits.","failureModes":["Missing required 'diameter' or 'propertyClass' parameters returns a validation error","Diameter outside 3–48 mm range is rejected","propertyClass not one of 8.8, 10.9, 12.9 is rejected","nutFactor outside 0.08–0.4 range is rejected","preloadFraction outside 0.3–0.9 range is rejected","Non-standard pitch provided for a diameter without ISO coarse standard may produce degraded or null result","Network timeout or service unavailability returns HTTP error"],"whenToPreferThis":"Use this endpoint when you need a quick, standards-based bolt torque and preload estimate for ISO metric fasteners (M3–M48) in property classes 8.8, 10.9, or 12.9 without running full FEA or consulting physical torque tables. It is ideal for design checks, assembly procedure authoring, and tooling setup where a T = K·F·d estimate with proof-load-based preload is sufficient. Prefer alternatives when joint friction data is highly variable, when non-ISO (e.g. SAE/UNC) fasteners are used, or when friction-coefficient-based models (e.g. VDI 2230) are required.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-29T13:14:22.977Z","isFirstParty":false,"canonicalSlug":"machining-fasteners-calc-bolt-torque-fec1e810"}