Dial indicator (plunger type)Dial indicator / Mechanical dial gauge

≡Standards, measuring range and accuracy

Standard

• JIS B 7503:2017 Dial gauges
• JIS B 7563:2021 Digital indicator gauges
• ISO 463:2006 mechanical dial gauges
• ASME B89.1.10M Dial Indicators

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Measuring range

• General Standard models are 1–10 mm. Short models are 0.08 mm and long models 100 mm (Teclock goes up to 150 mm)
• byMaker
  • Mitutoyo 2044A 5 mm (graduation 0.01 mm)

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Resolution / graduation

• General 0.01 mm and 0.001 mm are typical. Teclock has 6 types from 0.0005 to 0.1 mm
• Digital 0.001 mm, etc.

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Accuracy (instrument error / maximum permissible error)

• Approach
  • JIS B 7503:2017 sets the indication error at 1/10 revolution, 1/2 revolution, 1 revolution, and over the full measuring range, plus return error, repeatability, and measuring force, each by a maximum permissible error (a permissible limit for measuring force)
  • Indication error is read at set intervals while pushing in the spindle (e.g., every 1/10 revolution for the first 2 revolutions), and read at the same points in the return direction
  • MPE values are at the standard temperature of 20 °C
  • Both Mitutoyo and Teclock inspect and guarantee accuracy in the vertical orientation (contact pointing down)
• byMaker
  • Mitutoyo 2044A (0.01 mm, 5 mm) 1/10 revolution 5 µm, 1/2 revolution 9 µm, 1 revolution 10 µm, full range 12 µm, return error 3 µm, repeatability 3 µm, measuring force 1.4 N or less

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▦Types

◎Part names and functions

◷How to read the scale

1. Read mm on the short hand and 0.01 mm on the long hand, and add themExample: short hand 2, long hand 37 divisions (graduation 0.01 mm) → 2 + 0.37 = 2.37 mm (calculated from the rule in the source)^[13][7]
2. In comparison measurement, read the push-in and return amounts from the zero position (the position set to 0) as + and −^[7][6]
3. Read the dial from the front (viewing from an angle causes parallax)^[6]

✋Usage steps

1. Operation check: check that the long hand, short hand, and spindle move smoothly and that the rest point is stable. Check that the contact point and the back cover (lug) are not loose^[7][6][11]
2. Mounting: fix it only by the stem or lug, and use a sufficiently rigid holder. With the contact point against the workpiece, lightly press the inner case with a finger from above and below, and judge the mounting by whether the long hand returns to the set positionWhen clamping the stem with a screw: mounting hole ø8G7, M4–M6, at least 8 mm from the lower end of the stem, maximum 150 N·cm with a single M5 clamping screw. Overtightening makes the spindle move poorly (Mitutoyo)^[6][11]
3. Orientation: mount the spindle parallel to the measuring direction (perpendicular to the measured surface). If it is tilted, the reading L2 differs from the actual displacement L1^[7][10][11]
4. Zero setting: consider the expected dimension range (tolerance plus margin) and set 0 near the middle of the measuring range. Even an unexpected dimension can then be read within the range^[7]
5. Set the origin or preset of a digital type with the spindle lifted at least 0.2 mm from its rest end (the range within 0.2 mm of the end is outside the accuracy guarantee)^[10][5][11]
6. Measurement: read the difference from a master (comparison measurement), runout of rotating parts, flatness, etc. Preferably, slide the workpiece along a backing piece (stop) in the direction that lets you view the gauge from the front^[7][8][6]
7. Do not move the spindle suddenly or apply sideways force^[6][11]
8. Where the temperature varies, frequently check the long hand's set position with a master^[6]

!Common measurement mistakes and countermeasures

✓Care, storage, inspection and calibration

Care and storage

• Do not oil the spindle. If it moves poorly, wipe the upper and lower sliding surfaces with a dry cloth or a cloth with a little alcohol, and send it for repair if that does not fix it^[10][7][6]
• Wipe the cover glass with a soft dry cloth or a cloth with a little neutral detergent. Do not use organic solvents such as benzine, thinner, or alcohol^[6][7]
• Operating environment: temperature 0–40 °C, humidity 30–70 %, no condensation. Avoid dust, oil mist, and direct sunlight (Teclock)^[6]
• If the long hand or revolution counter is far off at the rest point, there may be internal damage. Do not disassemble; send it for repair^[11]
• Use the contact point and back cover specified by the manufacturer^[6]

Inspection and calibration

• JIS method: fix it on a support stand and, using a micrometer head or length-measuring machine as the reference, read the indication error at each point in the forward and return directions. For repeatability, move it five times at the same position and take the maximum difference; read measuring force with a spring scale^[5][6]
• Set the interval by in-house standard, considering frequency of use, environment, and manner of use, and inspect regularly^[6]

A dial indicator cannot measure on its own; it is a comparison measuring instrument used with a stand, magnetic base, or fixture (Mitutoyo, Teclock).

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