Speaking like a machinistRulers, calipers, micrometers

Clark Senior High

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Speaking in thousandthsWe talk in thousandths of inches.

 0.100 is read as 100 thousandths

 

0.10 and 0.1 are also read as 100 thousandths

 

0.125 is read as 125 thousandths

 

2.350 is read as 2 inches 350 thousandths

Micrometers & calipers are graduated in thousandths

One inch is divided into one thousand units: 1/1000 =. 001

 

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Converting fractions to decimal

• Divide top number by the bottom number.

– Example: • Converting the fraction

3/4 to a decimal

3 divided by 4 = 0.75

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Fractional Conversions

1/4=. 250

1/8= .125

1/16=. 0625

1/32=. 03125

1/64=. 01562

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Convert following fractions

3/32=______________

7/8=______________

3/16=_____________

5/32=_____________

15/64=____________

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Reading a steel-rule

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Watch the increments of the ruler / tape measure.

Rule Graduations

• Fractional– 1/64”, 1/32”, 1/16”– 1/50, 1/20

• 0.020 & 0.050

• Metric

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Practice reading a steel-rule

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Practice reading a steel-rule

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Practice reading a steel-rule

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Practice reading a steel-rule

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1/50 & 1mm

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1/8 & 1/16”

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1/32 & 1mm

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Metric to English Conversion

Convert Metric to English using the constant of .03937.

Example: 15mm to English. 15mm x .03937=. 5906.

Convert the following:

12mm_______________

3.5mm_______________

7.62mm______________

1mm_________________

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English to Metric Conversion

Convert English to Metric using the constant of 25.4. Example: .150 to metric.

.150 x 25.4 = 3.81mm Convert the following:

.4725_______________mm

.1378_______________mm

.300 _______________mm

.3937_______________mm

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Note:

When talking or writing metric don’t forget to say millimeters or write “mm” after the number to show that it’s a metric number. With out it people look at is being English.

Always refer to the print for unit of measurement.

Dial Caliper

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Components of a caliper

Common Caliper sizes

• 4” becoming more common

• 6” is the most common

• 8”

• 12” – 2nd most common

• Larger•22

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Reading Dial CaliperIs similar to reading a micrometer as it broken down in a serious of steps.

In this picture above the caliper has been set at 1.157”. The following describes how this measurement was read. The jaw index has passed the 1 inch mark. 1.000The jaw index has passed the 1 on the revolution scale. .100The needle has passed the 50 on the dial numbers .050There are a total of 7 black line after the 50 mark .007The total measurement = 1.157”

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Another example of reading a caliper

Caliper Use

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Caliper PracticeSet the following on the caliper:

.051”

.125”1.237”2.499”3.627”4.985”5.573”6.000”

• (Class exercise, pass caliper around room for everyone to try. Also practice saying the reading)

Outside Micrometer

• Generally just called – Micrometer or– Mic.

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Reading a Micrometer

The main scale on a micrometer is on the sleeve and divides an inch into ten main segments numbered 0 through 9. Each of these ten segments represent .100 (one tenth of an inch). Each segment of .100 is divided into four parts, each one representing .025.

The rotating scale on the thimble represents .025 of movement for each 1 full revolution. The line down the middle of the sleeve is used to line up the thimble reading. To read a measurement you simply see how many .100 increments are visible then add the number of .025 increments visible then add the reading on the thimble.

Note: Always check a mic for zero before using and check the anvils for damage

• MICROMETER READINGS • The first step is to read how many

hundred thousandths are visible to the left of the thimble (BLUE) and write it down.

• The second step is to look for visible .025 inch lines on the sleeve (GREEN) and write that below the blue number.

• The third step is to look on the thimble (RED) for thousandths and write that at the bottom.

• Now add them.500.075 (three times .025 X 3= .075).007.582If the micrometer is larger than a zero to one inch micrometer you must add the appropriate number of inches to this reading.

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Find the following on the micrometer:

(Class exercise, pass mic around room for everyone to try. Also practice saying the reading)

Also discuss how to check mic for zero before using, how to hold mic, how to lock mic and things not to do with mic (spin fast, clamp to hard, ect)

Practice setting the micrometer

.051

.125

.237

.499

.627

.985

.5735

.7672

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Other Micrometers• Depth mic

– 0-6 inch• 4 inch base

• Bore mics• Thread mic• Blade mic• Etc.

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Other Measuring tools

• Gauge Block

• Pin gauge– Go / No GO

• Thread plug gage– Go / No Go

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Thread plug gage

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•Three turns before you feel drag

Jeopardy 1a Review

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