Mechanical Engineering Laboratory
New Jersey Institute of Technology
Report Submitted by
Nicholas Stremel
Date Performed
3/30/2023 +
4/6/2023
Course & Section
ME215-010
Experiment No.
Date Submitted
Instructor
4/13/2023
Veljko Samardzic
Measurement and Tolerance
Experiment Title
Performed by Group
010A2
With TA
Group Members
Nicholas Stremel
(leader)
(Indicate Leader)
Michael Kosakowski
Carlos Veira
Xavier Romero
Rumana Hasan
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Table of Contents
Abstract
Introduction
Objectives
Background and importance
Procedure
Results and Calculations
Discussion
Conclusion
Questions and Answers
Original Data Sheet
References
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Abstract
In this laboratory, we were introduced to Measurement and Tolerance. Our goal was to become
familiar with the process of measuring workpieces in an engineering context. Through a
presentation, we learned of the system of fits and tolerances. Following this, we were introduced
to the vernier caliper, micrometer, and thread pitch gauge. To gain a practical understanding, we
were tasked with using these instruments to measure the dimensions of five workpieces: a
shaft-hole, a bolt, a step-block, a CNC demo part, and a tapered shaft. To measure the taper angle
of the tapered shaft, we used both the optical comparator and a protractor. We used a thread
gauge to measure the thread of the bolt. In week two, we learned the basics of geometric
dimensioning and tolerancing and the symbols used in the system. We were then tasked with
verifying that dimensions of an aluminum CNC part and a shaft were correct. Using gauge
blocks and a dial indicator, we were tasked with finding the angle of a particular feature on the
CNC part. Using the same instruments, we were able to find the runout of the shaft. We found
that the calipers were the easiest and most efficient way to dimension the workpiece and that the
optical comparator worked best for measuring the taper angle.
Introduction
Measurement is the act of defining the lengths, angles, and locations of various features on a
workpiece. When measuring, there are three types of sizes: nominal (general identification),
basic (theoretical), and actual (measured). Deviation refers to the amount a measurement is
different from the expected size (basic). It is expressed in terms of maxes/mins.
Tolerance is the total amount a measurement is allowed to deviate whereas allowance is the
tightest fit between two mating parts. Limits represent two extremal possible sizes of dimension
(high and low). Fits represent the magnitude of tightness between two parts. There are three
types of fits: clearance (positive allowance), interference (negative allowance), and transition.
Objectives
The objective of this lab is to
1. Define various measurement and tolerance terms
2. Become familiar with various measuring instruments
3. Use measuring instruments to properly measure the dimensions of several workpieces
4. Learn the basics of geometric dimensioning and tolerancing.
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Background and importance
Measuring and tolerances help ensure products meet the necessary specifications. Tolerances
ensure that parts work, fit, and function correctly. Too loose or tight of a tolerance can result in
mechanical failure. Product quality and safety requires a strict attention to measurements and
deviations. Measuring can even reduce manufacturing costs as tight tolerances can increase costs
due to the high preciseness necessary to machine those parts.
Procedure
In Week 1, we were introduced to various measuring terms and definitions including deviation,
tolerance, sizes, limits, fits, and allowance. We were also introduced to the vernier caliper,
micrometer, optical comparator, and thread pitch gauge. Using these instruments, we were tasked
with measuring the dimensions of five workpieces and recording the measurements on sketches
of the part profiles. Four of the workpieces (the shaft-hole, bolt, step-block, and tapered shaft)
were sketched using rulers and a sketch of the five workpiece (CNC demo part) was provided.
To find the taper angle of the tapered shaft, we used both a protractor and the optical comparator.
To find the thread of the bolt, we used a thread gauge.
In Week 2, we learned the basics of geometric dimensioning and tolerancing and the various
symbols used in the system. We were given two more workpieces: an aluminum CNC demo part
and a shaft. We were tasked with measuring the dimensions of these workpieces and verifying
that they match the dimensions provided. Any deviations were recorded on the sketches. To
measure the runout of the shaft, we used gauge blocks and a dial indicator. To measure the angle
of a particular feature on the CNC part, we used the same instruments.
Results and Calculations
Overall, we were able to dimension all five workpieces accurately and efficiently. We found that
the vernier calipers were the most useful instrument and used it for a good portion of our
measurements. When measuring the taper angle, we found the protractor gave us the best results
and did not deviate much from the measurements found in the optical comparator. During the
second portion of the lab, we were able to verify the dimensions of the sketches provided and
understand the symbols used in geometric dimensioning and tolerancing. Overall, we found
small deviations within the measurements using vernier calipers but they were within the
provided tolerances. We found that the optical comparator gave us the best results when finding
the angle on the CNC part. The gauge blocks and dial indicator were quite difficult to use in this
context and gave us an inaccurate measurement. They were useful in finding the runout of the
shaft, however.
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Discussion
Overall, the lab was very successful in achieving the objectives. Through a presentation, we
learned the various terms and definitions that were essential for the lab. We learned how to
correctly use the various measuring instruments and became proficient in their use. We were able
to accurately and efficiently measure the dimensions of all the workpieces. We also became
familiar with symbols used in geometric dimensioning and tolerancing.
Our recorded dimensions were not far from the expectation. Using the calipers, we were able to
quickly find all of the dimensions, even in particularly difficult to measure corners. We also
expected that the optical comparator would be best for finding angles and our experience
confirms that.
There are many ways one could make a mistake during this laboratory. Some older calipers can
be a bit loose and the slider can be moved by accident if one is not careful. Also, the gauge block
and dial indicator can easily become difficult to work with if the table is not steady during
measurement.
Conclusion
As a class and as a group, We learned the basics of measuring terms and definitions. We learned
how to correctly use measuring tools and correctly measured the dimensions of seven different
workpieces. We were also able to accurately measure angles, threads, and shaft runout. Through
these exercises, we achieved all of our lab objectives and became familiar with the measuring
and tolerancing process.
Questions and Answers
Question 1: Define the meaning of allowance
Answer: Closest fit between two connecting parts.
Question 2: A shaft and a hole have a nominal diameter of 1 in. The shaft has a tolerance of
0.003 in, the hole has a tolerance of 0.004 in and the allowance is set at 0.001 in. Show the
deviations for the shaft and the hole from nominal size, calculate the maximum and minimum
clearance for two mating parts.
Answer: minimum clearance = 0.001 in., maximum clearance= 0.008 in.
Question 3: Explain the difference between clearance and interference.
Answer: Clearance fit is the air space between the shaft and the hole. Interference fit is a
negative allowance between the shaft and the hole. In other words, the shaft does not fit.
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Question 4: What two ways can be used to check the accuracy of the micrometer
Answer: Using a standard gauge and comparing it with another calibrated micrometer . It can
also be checked using slip gauges and a gauge block.
Question 5: What is meant by the term tolerance
Answer: an undesired but acceptable deviation from the intended size
Question 6: Give the total readings of instruments shown in the figure.
Answer: A) TOTAL VALUE = 1.5 + (16 x 0.02) = 1.5 + 0.32 = 1.82 mm
B) TOTAL VALUE = 6.5 + (19 x 0.01) = 6.69 mm
C) TOTAL VALUE = 3.5 + (16 x 0.01) = 3.66 mm
D) TOTAL VALUE = 4.5 + (11 x 0.01) = 4.61 mm
Question 7: Calculate allowance and tolerance for three mating parts in the shaft-bearing-frame
assembly shown in the figure.
Answer:
Tolerance
for shaft : 1+.005-(1+0.003)=1.005-1.003=0.002
for outer radius - 3+0.0-(3-0.003) = 0.003
for inner radius 1+0.002-1=0.002
for frame : 3+0.004-3=0.004
allowance for bearing and shaft = -0.001
allowance for bearing and frame = 0.007
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Original Data Sheet
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References
Black, J. T., & Kohser, R. A. (2019). DeGarmo's Materials and Processes in Manufacturing.
Wiley.
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