Measuring Instruments and Techniques
Copyright R. Mahoney 2010
Name: _____________
The purpose of this lab is to familiarize yourself with certain basic length
measuring devices, the two trivial systematic measuring errors associated with
analog measuring devices, and how to state a single measurement correctly on a
device by device basis.
A digital caliper will be made available to the class for comparison purposes.
Please answer the interspersed questions (Q) at the end of this lab handout.
1. There are three length measuring devices in the kit given you: a ruler, an
analog vernier caliper, and an analog micrometer. There are also a variety of
items whose dimensions can be measured by these devices.
Q1: Which device is best suited for measuring the diameter of the spherical ball?
Q2: Which device is best suited for measuring the inner diameter of the
cylindrical tube?
2. We will only concern ourselves in this lab with metric measurements.
What is the metric least count of the ruler? Answer: _____ mm
What is the metric least count of the analog vernier caliper? Answer: _____ mm
What is the metric least count of the analog micrometer? Answer: _____ mm
For a single measurement, what are the corresponding tolerances of each
measuring device?
Ruler: _____ mm
Caliper: _____ mm
Micrometer: _____ mm
Which of the three devices is the most precise? Answer: ____________
3. The block is nominally dimensioned to be 2" x 1" x 0.5" (L x W x D).
Q3: Knowing that each inch is 25.4 mm, what are the block's dimensions in mm?
Using the ruler, measure the block's width. Answer: ____________ mm
Q4: Did you use the edge of the ruler to make this measurement? Do you get
the same result if you line up one side with a major marking on the ruler (like the
10 mm or 1 cm mark)?
4. Use the vernier caliper to measure the inner diameter of the cylindrical tube
and write down your single measurement, including tolerance. Check for zero
error with the caliper's tongs closed.
Answer: ____________ mm
Now make this same measurement five times in a row (skip writing the
tolerances here). You don't have to measure at the same exact inside spots.
Answers: __________ __________ _________ __________ __________
Are the measurements the same, or different? Yes / No (circle one).
If your measurements vary, do they vary because they are really different values,
or because of parallax, or for both reasons? Answer: _____________________
5. Use the micrometer (mic) to measure the diameter of the spherical ball.
Check for zero error with the mic faces (anvils) closed. Be sure to use the clutch
release on the mic to avoid making measurements that are too tight or too loose.
Answer: ____________ mm
Q5: Is it possible (using the mic) to measure something other than the true
diameter of the ball?
Now make this same measurement five times in a row (skip writing the
tolerances here). You don't have to measure at the same exact same opposite
spots.
Answers: __________ __________ _________ __________ __________
Compute the average measurement. Answer: _________
6. Answers to interspersed questions: