How to use a depth micrometer

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Step 1 – Insert spindle

Ensure that the micrometer is first zeroed by inserting the 0-25mm (or 0-1″) rod and refering to the section on zeroing your micrometer.

Roughly estimate the distance to measure using a rule or tape measure. Use this estimate to select the appropriate extension tube, and insert into the bottom of the micrometer.

Step 2 – Position

Place the measuring rod into the hole or onto the step being measured, as close to the edge (but not touching) as possible.

Step 3 – Turn thimble clockwise

Holding the base of the micrometer, turn the thimble slowly and in a clockwise direction until the tip of the rod is close to the bottom of the hole or step.

Carefully turn the ratchet as you approach the surface to be measured and continue turning until the spindle stops rotating.

Using the micrometer thimble alone requires a degree of skill and practice to achieve the correct “feel”.

Step 4 – Lock spindle

Lock the micrometer spindle using the locking device and carefully remove the instrument from the workpiece.

Step 5 – Read measured value

Read the measured value, and add this to the length of the extension rod used. (See How to Read a Micrometer).