TOOL-M 24
COMPETENCY
Demonstrate the correctly use of a dial caliper.
ADMINISTRATION
DEMONSTRATE: The Qualifier will have the employee demonstrate the versatility of a dial caliper. The Qualifier will have the employee take three measurements with a dial caliper to obtain an outside diameter, inside diameter and depth measurement.
PROCEDURE
The employee will demonstrate as follows:(Figure 13)
1. How to use a dial caliper?
2. How to read the scale?
Answer:
1. A dial caliper can be used to take three different types of measurements.
a. Inside diameter measurements
b. Outside diameter measurements
c. Depth measurements
2. Procedure for using a dial caliper to obtain an outside diameter measurement.
NOTE: The steps listed below outline a generic procedure:
a. Loosen the slide bar lock.
b. Clean all dirt and grit from the caliper jaw contact surfaces, using a lint free cloth.
c. Rotate the thumb wheel until the outside caliper jaws are fully closed.
d. Loosen the dial lock and turn the dial face until the needle reads zero, and tighten the dial lock.
e. Clean all dirt and grit from the item being measured, using a lint free cloth.
f. Rotate the thumb wheel to open the outside caliper jaws slightly wider than the item being measured.
g. Position the caliper jaws over the item being measured. h. Ensure the caliper jaws are squared in relation to the item being measured. i. Slowly close the caliper jaws with the thumb wheel until the jaws lightly contact the item being measured and tighten the slide bar lock.
j. Read the dial caliper.
1) Add the total number of marks on the bar between the caliper jaws. Each mark represents .100" (e.g., 27 marks = 2.700").
2) Obtain the indicated reading on the dial face. Each mark represents .001" (e.g., the pointer on the dial face indicates 25 = .025").
3) Add the bar reading to the dial face reading to obtain the diameter of the item being measured (e.g., 2.700"). +.025" = 2.725"