{
  "id": "ra-ladder",
  "source": "https://ctrlplanner.com/convert",
  "license": "CC-BY-4.0",
  "attribution": "ctrlPlanner, https://ctrlplanner.com/convert",
  "title": "Surface finish preferred-number ladder, Ra",
  "standard": [
    "ISO 4288",
    "ASME B46.1"
  ],
  "description": "Paired standard Ra values in microinches and micrometers. These are entries on a preferred-number series, not conversions of one another: each is a standard value in its own right.",
  "unitsNote": "raMicroinch and raMicrometer are paired rungs. ifDivided is what dividing the microinch value by 39.37 produces, which is not a value any finish specification uses.",
  "rows": [
    {
      "raMicroinch": 500,
      "raMicrometer": 12.5,
      "ifDivided": 12.7
    },
    {
      "raMicroinch": 250,
      "raMicrometer": 6.3,
      "ifDivided": 6.35
    },
    {
      "raMicroinch": 125,
      "raMicrometer": 3.2,
      "ifDivided": 3.175
    },
    {
      "raMicroinch": 63,
      "raMicrometer": 1.6,
      "ifDivided": 1.6
    },
    {
      "raMicroinch": 32,
      "raMicrometer": 0.8,
      "ifDivided": 0.813
    },
    {
      "raMicroinch": 16,
      "raMicrometer": 0.4,
      "ifDivided": 0.406
    },
    {
      "raMicroinch": 8,
      "raMicrometer": 0.2,
      "ifDivided": 0.203
    },
    {
      "raMicroinch": 4,
      "raMicrometer": 0.1,
      "ifDivided": 0.102
    },
    {
      "raMicroinch": 2,
      "raMicrometer": 0.05,
      "ifDivided": 0.051
    },
    {
      "raMicroinch": 1,
      "raMicrometer": 0.025,
      "ifDivided": 0.025
    }
  ]
}