Precision Outside Circumference Tape

Example:

Make certain the tape and object to be measured are both clean.
Each line on the gage member represents .025” of circumference, while each line on the vernier represents .001”.
Wrap the tape around the object to be measured. The vernier scale should be just below the
gage member. Tighten the tape around the object with 5 pounds tension for O.C. tapes (For I.C. tapes, use 0
pounds tension).
Locate the “zero” on the vernier scale and note the highest value achieved on the gage member above it (the
highest value to the left of the zero). In this example, the value is 19.900” plus 2 lines or 19.950”.
Next, observe the vernier scale’s value at the point where it lines up exactly with a marked division line on the gage
member. In this example, the value is 5 (.005”).
Finally, to obtain the circumference of the object, simply add the two values together:
19.950” + .005” = 19.955”.
When using a standard O.C. tape on an I.C. surface, add double the tape thickness to the reading to arrive at the I.C.
of the part. It is suggested that direct I.C. tapes be used for inside circumference readings.
As a suggestion for checking very large circumference – pieces of masking tape can be used to hold the tape in the
proper parallel position.
Tape resolution 0.001″