---
title: Vernier caliper
lang: en
type: notion
tags:
  - mme
  - notion
prerequis: []
aa: []
draft: false
source_fr: meca/pied-a-coulisse.md
source_sha256: 00a46ccf84ff21f3630c68eb3fe6317b291b6acad588e41e8ec04f427d0b281f
---

The **vernier caliper** is the workshop's basic dimensional measuring instrument: it gives an **absolute dimension** (a length, an outside or inside diameter, a depth) to a tenth of a millimetre, or a hundredth on digital models.

![Diagram of a vernier caliper: a graduated beam with a fixed jaw and a sliding jaw. The lower jaws close on a part to read a length or an outside diameter, the upper jaws read an inside diameter, and a depth rod extends from the right to read a depth. Every one of them is an absolute dimension.](/ressources/img/pied-a-coulisse/mesures.svg)

## In the project

It is the first tool to reach for when checking that a manufactured part matches its dimensions: a shaft bore, a mounting hole spacing, a thickness. On the running example, it serves for the dimensional inspection of parts during [[integration-et-tests-en|integration and testing]], and for the traceability of the assemblies. A good habit is to measure the **critical dimensions** identified in the [[dossier-technique-en|technical design file]] rather than measuring everything, and to zero the instrument before each batch.

*Good measuring practice, including contact pressure, reading the vernier scale and the sources of uncertainty, belongs to the metrology lab sessions. The wiki places the instrument within the project.*

## See also

- [[comparateur-en|Dial indicator]] — for measuring a variation rather than a dimension
- [[integration-et-tests-en|Integration and testing]] — dimensional inspection of manufactured parts
- [[dossier-technique-en|Technical design file]] — where the critical dimensions are defined
- [[precision-de-mesure-en|Accuracy, trueness, precision]] — resolution is not accuracy (cross-cutting to any measurement)
- **Mechanical engineering and metrology course** (colleagues) — reading, uncertainties