1. The Outside Micrometer
Parts of The Metric and Imperial micrometer

2. Metric micrometer thimble sleeve anvil spindle ratchet lock frame
Scale

3. Sleeve The Imperial micrometer Sleeve
Has 40 graduations along its length of 1 inch
Each graduation is 1/40 of an inch =0.025inches
Every 4th graduation is larger =1/10 of an inch or =0.1 inch

4. Sleeve The metric micrometer sleeve has a total length of 25 mm
The sleeve is broken down in 5 main sections of 5 mm each
Every 5mm section is further broken down to give 10 equal segments with each =0.5mm
Therefore there are 50 divisions on the sleeve

5. The Thimble This is the part that is turned
The imperial scale has 25 graduations around the the thimble scale that is numbered 0-25
Each graduation =0.001 inches
This gives accuracy to inches

6. The metric thimble This has the part that is rotated
Contains a scale that is around the outside of the thimble
It has 50 divisions numbered 0-50
Each division is 0.01 mm
This gives accuracy to 0.01mm

7. The Ratchet Located at the end of the thimble
Used to control the force or load applied to the micrometer or the work being measured
Prevents the micrometer from being over tightened
When max load reached it will make a clicking sound. Some types use a sliding clutch

8. The spindle
The spindle is a sliding plunger that moves in a linear direction
One revolution of the thimble moves the spindle 0.025” or 1 graduation on the sleeve
The spindle carries the second of the measuring surfaces that contacts the object being measured

9. The Frame and Anvil
The frame is the main support member for all other parts of the micrometer
The anvil is located in the far end of the frame and provides the fixed measuring surface
The frame will have the size and type of micrometer marked on it
They are usually made from cast of iron

10. The lock May be of a lever type or a roll type
Locks the spindle to the sleeve so that readings can be taken easily
Allows you to capture the reading of the scales

11. The Vernier scales
This is a new scale that is located on the sleeve near the frame
Allows you to read inches or mm
The scale is a subdivision of the thimble scale and breaks 0.001” down by 10 = or, on the metric scale 0.01mm divided by 10 =0.001 mm

12. Standard micrometer Vernier scale lock thimble ratchet anvil spindle
sleeve
Decimal
readout
frame
scale