Source: https://guthlabs.ai/docs/instruments/bolt-torque-to-preload-calculator/implementation/

instrument implementation / implementation-contract

# Bolt Torque-to-Preload Calculator implementation

A source-bound implementation contract for Bolt Torque-to-Preload Calculator; deployment and executable qualification remain separate.

Status: **VERIFIED_WITH_ERRATA**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-with-binding-errata

**Evidence ID**: t5-031

**Effect**: Computation or source lookup only

## Input and validation requirements

The inverse calculation is undefined when K·d=0 and should reject the input. The result is also highly sensitive to the dry-versus-lubricated K-factor branch and to diameter units; a unit misinterpretation changes 10 N·m to 10000 N·m.

## Required corrections

````
[
  {
    "vector": 2,
    "field": "torque(_converted)",
    "wrong": "4572 N·mm / 4.572 N·m",
    "correct": "45720 N·mm / 45.72 N·m",
    "cause": "0.18×12.7×20000 dropped a zero; her v3 imperial case exact"
  }
]
````

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "bolt_diameter": 0.01,
    "diameter_unit": "m",
    "target_preload": 25000,
    "preload_unit": "N",
    "nut_factor": 0.2
  },
  "expected_outputs": {
    "torque": 50,
    "torque_unit": "N·m"
  },
  "working": "T = K·d·F = 0.20 × 0.010 m × 25,000 N = 0.002 × 25,000 = 50 N·m."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/bolt-torque-to-preload-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/bolt-torque-to-preload-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/bolt-torque-to-preload-calculator/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche5/tranche5-results.json`

- `tranche errata record`