Using the Vernier Caliper and the Micrometer A Powerpoint Presentation by Mr. Fernando D. Nolasco

Try this. When you use your ruler, how do you measure the diameter of a PENCIL OR A PEN TUBE?

A Better Way

Vernier Caliper

Parts of a Vernier Caliper Internal Jaws External Jaws

Parts of a Vernier Caliper

Two Scales Are Better Than One The vernier caliper has two scales: the main scale and the vernier scale The main scale is similar to the scale found on an Orion plastic ruler, graduated in millimeters (mm). The vernier scale is graduated into 0.050 mm marks.

Main Scale Vernier Scale

0.000, 0.050 0.100, 0.150, 0.200, 0.250, 0.300, etc Vernier Scale

Reading the Vernier Caliper Locate the “0” mark on the vernier scale. Determine the last mark on the main scale which was passed by the “0” mark of the vernier scale. (to the left) Determine which mark on the vernier scale lines up with ANY mark on the main scale. Complete the reading by adding the doubtful figure, usually “0” and the units (i.e. mm)

13

13

13.65

! ! ! ! ? 13.650 mm

23

23

23.70

! ! ! ! ? 23.700 mm

48

48.55

! ! ! ! ? 48.550 mm

75

75.40

! ! ! ! ? 75.400 mm

Micrometer

http://feh.eng.ohio-state.edu/tutorials/micrometer/parts.html

Two Scales Are Better Than One The micrometer has two scales: the main or linear scale and the rotating scale. The main scale or linear scale is graduated into 0.500 mm marks. The rotating scale is composed of 50 divisions, each graduated into 0.010 mm marks.

Linear scale divided into 0.500 mm marks

Whole Marks: 0.000, 1.000, 2.000, 3.000, etc Half Marks: 0.500, 1.500, 2.500, 3.500 etc

Rotating scale with 50 divisions, each equal to 0.010 mm

Like Clockwork The micrometer scales work like the minute and hour hands of a clock. Each complete revolution of the minute hand (12 numbers) advances or sets back the hour hand by 1 number. Each complete rotation on the rotating scale (50 divisions) advances or closes the linear scale by 0.500 mm.

Micrometer closed - 0.000 mm

After first rotation - 0.500 mm

After second rotation - 1.000 mm

After third rotation - 1.500 mm

! ! ! ? Linear Scale: 3.000 Rotating Scale: 0.270 Reading: 3.270 mm To get the final reading, simply add the readings on the linear and rotating scales Linear Scale: 3.000 Rotating Scale: 0.270 ! ! ! ? Reading: 3.270 mm

Linear scale: 6.500 Rotating scale: 0.170 ! ! !? Reading: 6.670 mm

Linear scale: 1.000 Rotating scale: 0.205 ! ! !? Reading: 1.205 mm