Label the Parts of a Micrometer – Numbered Worksheet

All 10 parts on the diagram

Show the list

Start here: 6 main parts 6

Frame The C-shaped body holding the anvil and spindle in line.
Anvil The fixed face the object rests against.
Spindle A precise screw that closes on the object from the other side.
Thimble The part you turn to move the spindle.
Sleeve (barrel) The fixed tube that carries the main scale.
Ratchet stop Slips at a set force, so every reading uses the same pressure.

Frame, anvil and spindle 2

Spindle lock Holds the spindle still while you read the measurement.
Heat insulator A plastic plate that keeps hand heat from changing the reading.

Sleeve, thimble and scales 2

Sleeve scale The main scale along the sleeve, read first.
Thimble scale The scale round the thimble's edge, read against the sleeve's line.

How this list was compiled: Read 2026-09-26. (1) Wikipedia, Micrometer (device), https://en.wikipedia.org/wiki/Micrometer_(device) : frame, anvil, spindle (a very accurately machined screw), sleeve (barrel or stock, with the linear scale), lock nut (lock-ring or thimble lock, holds the spindle stationary), thimble, ratchet stop, insulating plastic plates on the frame, scale markings on the thimble and sleeve. (2) Mitutoyo, Quick Guide to Precision Measuring Instruments, https://www.mitutoyo.com/webfoo/wp-content/uploads/E11003-Quick-Guide.pdf and https://www2.mitutoyo.co.jp/eng/pdf/E4329_QuickGuide.pdf : frame, anvil, measuring faces, spindle, spindle clamp or spindle lock, sleeve (outer sleeve), sleeve scale, thimble, thimble scale, index (fiducial) line, ratchet stop, heat insulator, adjusting nut. Licence: own work

The drawing: Drawn for this site by script, 2026-09-26. Own work, nothing traced. Licence: own work

How it works

Label the parts of a micrometer by number: 1 to 6 are the main parts, frame to ratchet stop; 7 to 10 are two fittings on the frame and the two scales. Each number has a line for its name.

Read the full guide

Micrometer word bank

In alphabetical order: anvil, frame, heat insulator, ratchet stop, sleeve (barrel), sleeve scale, spindle, spindle lock, thimble, thimble scale.

Numbers that get swapped

Across the gap, 2 is the short stop on the left jaw (anvil) and 3 the longer rod coming out of the frame (spindle). Two lines end on the tube beside the frame: 9 comes down to its row of marks (sleeve scale) and 5 up to the tube itself (sleeve). Further right, 10 ends on the marked edge where the thick barrel meets the tube (thimble scale), 4 on the barrel's grip (thimble) and 6 on the small knob at the far end (ratchet stop). 1 is the C shape (frame) and 8 the plate in its curve (heat insulator).

When marking, barrel or stock is right on line 5, and lock nut or lock ring on line 7.
The two scales carry no figures on this drawing: the sheet asks for names, not for a reading.

Questions and answers

What is the difference between the anvil and the spindle of a micrometer?

The anvil is fixed to the frame, and the object rests against it. The spindle moves: turning the thimble brings it toward the anvil until both lightly touch the object.

Where is the screw in a micrometer screw gauge?

Inside the sleeve, where it cannot be seen, so it has no number on the worksheet. The spindle is a very precisely cut screw, and turning the thimble moves it.

How many divisions are on the thimble of a micrometer?

On an ordinary metric micrometer, 50, each worth 0.01 millimeter: one full turn moves the spindle 0.5 millimeter. An inch micrometer has 25, each worth 0.001 inch.

Why is the frame of a micrometer so thick?

So that it does not flex, expand or contract, which would distort the measurement. It is heavy too, so the warmth of the hand holding it heats it only slowly.