Measurement Tools Flashcards
How precise is basic (non-precision) measurement?
Basic (non-precision) measurement is measurement to within 1/64 inch (0.5 mm).
What is comparison measurement?
Comparison measurement involves comparing an object to a known reference.
Such as:
* Rules and squares,
* Tape measures,
* Protractors,
* Drill size gauges,
* Drill point gauges,
* Radius gauges, and
* Surface finish indicators.
To what graduation values can 6-inch steel rules typically measure?
- Fractional inch rules cannot measure any closer than 1/64 inch.
- Decimal inch rules measure to 1/100 inch (0.010 inch).
- Metric rules measure to 0.5 mm.
How accurate is a good steel rule over 6-inches?
0.003 inch over 6 inches.
How do you measure a workpiece using a steel rule?
- Use the side of the rule with the largest graduations (1/8 inch; Figure 5) first.
- Check to see if the work lines up with one of the graduations (1/16 inch).
- If not, check the next largest graduations.
- Keep using successively finer graduations until the workpiece lines up properly.
- Do not guess a size if it falls between graduations.
What are the typical tape measure markings in imperial and metric?
- Foot-inch and continuous inch.
- Metric.
- Continuous inch and metric.
What is the accuracy of the following protractors:
1. Plate protractor.
2. Bevel protractor.
3. Universal bevel protractors.
- Plate protractor - 1-degree
- Bevel protractor - 1-degree
- Universal bevel protractors - Five minutes (5’) of a degree
What is a surface roughness comparator gauge?
One method of checking surface finish is to use a set of standard finish specimens made up into a surface roughness comparator gauge. The gauge consists of small blocks or plates that have been machined to a range of surface textures, from smoothest to roughest.
What is the tool in the image?
A combination square.
What is the tool in the image?
A solid square.
What is the tool in the image?
A plate protractor.
What is the tool in the image?
A bevel protractor.
What is the tool in the image?
A drill point gauge.
What is the tool in the image?
Radius gauges.
What is a transfer measurement tool?
A measuring instrument that does not have the capacity to show a measurement. A comparison measuring device must be used to get the actual value from the transfer tool.
What is the tool in the image?
Outside and inside spring calipers.
What is the tool in the image?
Outside and inside firm joint calipers.
What is the tool in the image?
Outside and inside lock joint transfer calipers.
- Used when it is necessary to clear an obstruction.
What is the tool in the image?
Telescoping gauge.
What is the tool in the image?
Small hole gauges.
How precise is precision measuring?
Precision measurement involves magnifying very small increments of size to make them visible to the naked eye. These increments can be as small as 0.001 inch (0.02 mm).
How do you read a vernier degree scale on a universal bevel protractor?
- Determine the direction in which the main scale increases. This example is clockwise.
- Read the vernier in the same direction.
- Find where the zero-mark line on the vernier scale crosses the main scale. This example is just past the 62-degree mark, clockwise.
- The main scale reading is 62 degrees (plus what is on vernier).
- Find where the vernier scale coincides with a line on the main scale. This example is at 30 minutes (30’).
- Add the vernier-minutes reading to the main scale-degree reading. In this example, the main scale 62° plus 30’, which equals a reading total of 62° 30’.
How do you get proper alignment and a proper measurement using a vernier caliper?
To get proper alignment, position the workpiece as close to the beam as possible.
What are the two reading styles for dial indicators?
Continuous and balanced.
- The balanced reading is numbered in both directions from zero (Figure 65A).
- The continuous reading is numbered from zero in one direction (Figure 65B).
What are dial test indicators also known as?
Last word indicator.
What are back plunger dial test indicators most commonly used for?
Shaft alignment.
What are the two errors encountered when using dial indicators?
- Spindle travel - the greater the distance there is to travel, the more that errors can creep into an indicator reading.
- Cosine error - misalignment of a dial indicator with the axis of measurement can occur.
How is a dial bore gauge used?
Each bore would be measured in three locations, staying off the parting line. Overall sets of measurements should be taken at the front and at the rear of each bore.
What is a crankshaft deflection gauge used for?
It is used for checking bearing alignment or shaft deflection without dismantling the engine or compressor. This inside measuring gauge checks the distortion of the crankshaft webs. This distortion bears a direct relationship to existing misalignment or excessive bearing wear.
What is the tool in the image?
A vernier height gauge.
What are the basic parts of a micrometer?
The basic parts of a micrometer are:
* Anvil.
* Frame.
* Spindle.
* Sleeve.
* Thimble.
* Ratchet.
* Lock nut.
How must a micrometer be aligned to the work?
The micrometer must be at right angles to the surface of the work.
When measuring a round workpiece, make sure the micrometer is positioned over the maximum diameter.
What is the lead on an imperial micrometer?
The imperial micrometer uses a screw thread with a pitch of 0.025 inch.
The spindle moves 0.025 inch every complete thimble revolution.
What is the reading of the micrometer in the image?
0.635-inch.
What is the lead on a metric micrometer?
The pitch of a metric micrometer screw is 0.5 mm. Every time the screw is turned one complete revolution, the spindle moves half a millimeter. If the screw is turned 1/50 of a revolution, the spindle moves 0.01 mm.
What is the reading of the micrometer in the image?
16.87 mm.
What precision does a vernier micrometer read to?
A vernier micrometer uses a vernier scale to allow readings to 0.0001 inch or 0.002 mm.
What is the reading of the vernier micrometer in the image?
0.5282-inch.
What is the trick to properly using an inside micrometer?
The trick to measuring a bore accurately is to align the measuring tool.
For use of the inside micrometer there are two major considerations:
* Across the diameter of the bore and
* At right angles to the axis of the bore.
What is the tool in the image?
An Intrimik.
How is the intrimik used?
An Intrimik, has three contact points rather than two; this makes it self-centering. The measurement is thus taken across the true diameter. A small cone inside the Intrimik forces the three jaws outward at right angles to the axis of the micrometer screw. The Intrimik has a limited range (typically 0.400 inch).
What is the tool in the image?
A depth micrometer.
How do you calibrate an outside micrometer?
- Engage the pin of the adjusting wrench in the small hole at the base of the sleeve.
- Rotate the sleeve with the wrench until the lines coincide. This may require considerable pressure.
- Open the micrometer, close it again and recheck the zero setting. Repeat the procedure if necessary.
What is the tool in the image?
Taper gauges.
What are taper gauges used for?
A taper gauge is a direct reading tool. They are used to:
* Determine the width of a slot or the diameter of a hole and
* Measure angularity in coupling shaft alignment.
How are taper gauges used to check the amount of angular misalignment between shafts?
It is first inserted between the gap at the top of the couplings (12 o’clock position) and a reading is taken. Then, both shafts are rotated together so that the shaft positions that were at the top are now at the bottom (6 o’clock position) and a second reading is taken. The difference between the readings is the amount of vertical angular misalignment.
Determine the reading for the micrometer in the image.
0.529-inches.
Determine the reading for the vernier caliper in the image.
3.788-inches.
Why should you not be rough with vernier calipers when measuring using the points of the jaws on the slide caliper?
The jaws on slide calipers wear quickly and the thin points of the jaws are especially prone to damage
What is nominal size?
Nominal size refers to an imperial or metric standard size, which is used for the purpose of general identification.
What is basic size?
Basic size is the theoretical size to which the tolerances are applied. Basic size can refer to both mating parts.
What is limits of size?
Limits of size are the largest (upper limit) size and smallest (lower limit) size a part can be and still be acceptable.
What is the maximum material condition?
Maximum material condition (MMC) is where both mating parts have the most mass (metal), which would be the smallest hole and the largest shaft.
The opposite condition is the least metal condition (LMC), which is the largest hole and the smallest shaft.
What is tolerance?
Tolerance is the total amount of variation permitted in the size of duplicate parts.
It is the difference between the largest and the smallest permitted size.
What is the MMC and LMC of the parts in the image?
MMC = Smallest hole - Largest shaft
MMC = 1.000” - 0.9975”
MMC = 0.0025”
LMC = Largest hole - Smallest shaft
LMC = 1.0020” - 0.9963”
LMC = 0.0057”
What is unilateral tolerance?
Unilateral tolerance is in one direction only from basic size and there is no variation (zero) in the other direction.
What is bilateral tolerance?
Bilateral tolerance is in both directions (equally or unequally) from basic size.
What is the limit dimension method?
In the limit dimension method only the maximum and minimum dimensions of the part are specified. The dimensions are stacked, with the larger dimension placed on top.
What is allowance?
Allowance is the intentional difference between two mating parts at MMC. The MMC is used to determine the allowance and the type of fit.
What is positive allowance?
In a condition called positive allowance, the hole is to be larger than the shaft. This is a clearance fit.
What is negative allowance?
When the hole is smaller than the shaft the MMC calculation produces a negative value called negative allowance. This is called an interference fit.
What are the three fit types?
- Interference fits, which have a negative allowance, and the total tolerances which do not exceed the allowance.
- Clearance fits, which have a positive allowance.
- Transition fits, which have a negative allowance, but the total tolerances exceed the allowance.
What is the coefficient of linear expansion?
Every material has a set rate of expansion for every degree of temperature change. This constant is called the coefficient of expansion.
What is the formula for calculating change in length of metal due to temperature change?
ΔL = Lo × ΔT × α
Where:
ΔL = Change in length
Lo = Original length
ΔT = Change in temperature
α = Coefficient of linear expansion
For calibration, what is an end measuring rod?
The end measuring rod is the standard that is used to check and calibrate the outside measuring tools such as the micrometer.
What are ring gauges?
Use the ring gauge to check the accuracy of the inside micrometers.
A ring gauge’s purpose is the same as the end measuring rods. However, while the end rods are for outside measurements, the ring gauge is used for inside measurements.
What is a gauge block?
A gauge block is a precision ground steel or ceramic block. These blocks can be used to check calibration on outside measuring tools, as well as dial indicators and height gauges.
