# Machining & Fasteners Calc – Bolt Torque

> Machining & Fasteners Calc – Bolt Torque is a paid API for AI agents from machining-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).

Calculates ISO bolt preload force and tightening torque using T = K·F·d for property classes 8.8, 10.9, and 12.9

## Facts

- Endpoint: GET https://machining-calc.x402tookit.com/bolt-torque?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/machining-fasteners-calc-bolt-torque-fec1e810
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_LB5QucRrqFut07vX_sYp6

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability machining-fasteners-calc-bolt-torque-fec1e810
```

Example prompt: 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.

## When to prefer this

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.

## Known failure modes

- 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

## How this service works

Bolt preload (75 percent of proof) and tightening torque estimate T = K F d for ISO property classes 8.8, 10.9, 12.9.

## Output

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.

## Request schema (JSON Schema)

```json
{
 "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"
       ]
    
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/machining-fasteners-calc-bolt-torque-fec1e810/health.json
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