M A E 2 3 8 1
R E L E A S E 5
2 / 3 / 2 0 0 9
Dimensional measurements and uncertainty analysis
The aim of this laboratory is to familiarize students with several geometrical measuring instruments
and determine their accuracies, limitations, and capabilities.
Note: This lab does not require a diagram of data flow for Lap prep.
What you will learn
Principles of linear measurement
Elements of report writing
Introduction to instrument characteristics
Equipment you need
Micrometer depth gauge
Manufactured “pin” for inspection
In this lab, we will use instruments using the inch scale
Note down manufacturer’s name, serial and model numbers (if present) of all the
instruments and the sample pin, so as to able to identify them precisely, including the specimen pin (select
and use that particular one throughout this lab), the steel ruler, the Vernier caliper, the micrometer
caliper and the micrometer depth gauge (refer to
). If no identification number is present, write down
what is available.
Estimate the resolution (least count) accuracy of each of the provided measuring devices and
values in your laboratory notebook. Verify the following.
Steel Ruler (0.01 inch)
Vernier Calipers (0.001 inch) (VC)
Micrometer Calipers (0.001 inch) (MC)
Micrometer Depth Gauge (0.001 inch) (MDG)
For VC, MC, MDG, you will see that each inch is divided into 10 decimals, each decimal is divided into 4 quarters
and each quarter is divided into 25 subdivisions, on the Vernier Scale on the VC or the circular scale in MC and
1 in./10/4/25 = 1/1000 inch.
*Adapted from D. D. Seath, MAE 2181 Laboratory Manual, The University of Texas at Arlington, 1998
Note down the maximum reading of each instrument. Verify the following: steel ruler (6 in.), Vernier calipers
(~5.2 in.), micrometer calipers (1.05 in.) and the micrometer depth gauge (1 in.).
Note down the zero error, if any of, all four instruments. What is zero error? If your car is sitting in the parking
lot and the speedometer reads 5 mph, then the speedometer has a zero error of 5 mph. In this case, you have to
subtract 5 every time you read the gauge. Similarly, for every analog instrument, one has to check for zero