An easy-to-follow guide for reading a micrometer screw gauge. a micrometer reading contains two parts:
- the first part is contributed by the main scale on the sleeve
- the second part is contributed by the rotating vernier scale on the thimble
Table of Contents
What Are the Parts of An Outside Micrometer?
The Three Steps of Measuring With a Micrometer:
- Clean the micrometer: The micrometer’s anvil and spindle should be cleaned with a gentle cloth. To ensure accurate measurement, clean the measuring faces of any dust or debris.
- Begin to measure: Set up the micrometer’s anvil against the item you are attempting to measure. The spindle should be firmly pressed against the object as you tighten the device. The locking lever or wheel can be used to lock your thimble in place if you need to stop it from turning. If you prefer, you can also secure the frame to a micrometer stand, which will free up both of your hands.
- Read the measurement: Follow the four-step measuring procedure that is described in more detail below.
How Do You Read Micrometers?
Follow This Simple Four-step Process to Read Micrometers:
STEP 1: Read the sleeve measurement
STEP 2: Next, read the thimble measurement
STEP 3: Now read the vernier
The vernier will give you your decimal measurement’s ten thousandth place.
Step 4: To total everything up
Add step 2 to step 1 (add your thimble measurement to our sleeve measurement), and then just “tack” step 3 (your vernier measurement) onto the end. As an example, if you’re measuring something that is 0.1234″, you’d find the .100 on the sleeve (step 1), the .023 on the thimble (step 2), and then you’d add. 023 to .100 for a combined .123. Then, simply add.0004 to the end by finding it on the vernier scale.
TECH TIP: It can be simple for beginners to make a mistake by leaving out the zero (.004) when adding the vernier scale’s.0004 to a number like.123, resulting in.127. It’s simpler to comprehend if you ignore the zeroes and simply place the value from the vernier scale onto the fourth place (the ten-thousandth place), at the end of the.123, to obtain the accurate measurement of.1234.
Micrometer Maintainance & Tech Tips
- Cleaning and maintenance: Before using the micrometer, remove all oil, dust, and dirt with care, being careful not to scratch the measuring faces. Before and after taking any measurements, clean the measuring faces with a clean cloth.
- When in doubt, calibrate the device. The horizontal line on the sleeve of a micrometer should coincide with the number 0 on the thimble when it is at its lowest reading. If that isn’t the case, rotate the sleeve to calibrate the micrometer. An adjusting wrench is provided with each micrometer for this particular use. Before each use, make sure the thimble’s “0” and the horizontal line on the sleeve line up.
- Storage of Micrometers: When not in use, keep your micrometer in a place that’s cool and free of heat, dust, humidity, oil, and mist. If your electronic (digital) micrometers will be stored for a long time, take the batteries out.
Measurement Reading Technique for Micrometer
The illustration up top shows a typical micrometer screw gauge and how to interpret it. Steps:
- The number 5 is located directly to the left of the thimble in the image above. This is where you should start your measurement. As you can see, there is an additional line beneath the datum line, which corresponds to an additional 0.5 mm. So the first part of the measurement is 5.0+0.5=5.55.0+0.5=5.5 mm.
- For the second component of the measurement, see the image above where the datum line on the sleeve and the number 28 on the rotating vernier scale coincide. Consequently, the second component of the measurement is 0.28 mm.
You just have to add the first part and second part of the measurement to obtain the micrometer reading: 5.5+0.28=5.785.5+0.28=5.78 mm.
To ensure that you understand the steps above, here’s one more example:
The first part of the measurement: 2.5 mm
The second part of the measurement: 0.38 mm
Final measurement: 2.88 mm
Compensating for Zero Error
In a Nutshell
Use the following formula:
Correct reading=Obtained reading–Zero error correct reading=Obtained reading–Zero error
where zero error zero error can be either negative (the “0” marking on the thimble is above the datum line) or positive ( the “0” marking on the thimble is below the datum line ).
