slip gauges

8/12/2019 Slip gauges

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Gage Blocks

Session 2


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Gage Blocks

Accepted standard of accuracy

Provides industry with means of

maintaining sizes to specific standardsor tolerances

Has led to higher rates of production

Makes interchangeable manufacturepossible


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Gage Block Manufacture

Blocks of hardened and ground alloy

steel

Stabilized through alternate cycles of

extreme heat and cold

Crystalline structure of metal left without

strain

Solid Cemented Carbide Ceramic


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Two measuring surfaces machined,

ground, lapped and polished to an

optically flat surface

Use optical flats to determine flatness

Made to a specific size

Accurate within range of 1 8 millionths of

inch

Accurate within range of 25 200 millionths

mm


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Size of each block marked on surface

Final calibration done where temperaturemaintained at 68F or 20 C.

Considered accurate to size only whenmeasured at this temperature

Available square, rectangular, and round


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Gage Blocks

Ceramic

Verses

Alloy


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Steel Block Advantage

Lower Cost

Good abrasion resistance 1/10 xceramic

Good Thermal expansion coefficient

Resistant to impact

Free from chipping

Wring together tightly


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Ceramic Block Advantage

Corrosion resistant

No detrimental effects as a result ofhandling

Superior abrasion resistance 10 x steel


Resistant to impact

Free from burrs



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Carbide Block Advantage

Corrosion resistant

No detrimental effects as a result ofhandling

Superior abrasion resistance 10 x steel


Free from burrs



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Gage Block Uses

To check dimensional accuracy of fixedgages to determine extent of wear,growth, or shrinkage

To calibrate adjustable gages To set comparators, dial indicators, and

height gages to exact dimensions

To set sine bars and sine plates whenextreme accuracy required in angularsetups


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Gage Block Uses

For precision layout with use of

attachments

To make machine tool setups

To measure and inspect accuracy of

finished parts


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Inch Standard Gage Blocks

Sets range from few blocks to as many as115

Most common is 83-piece set

Can make over 120,000 differentmeasurements


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Inch Gage BlocksTwo 0.050 inch wear blocks supplied

with some setsUsed at each end of build-up

Wear occurring during use will be onthese only

Good practice to always expose same

face of wear block to work surface

Prolongs life and accuracy ofset


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Metric Gage Blocks

Supplied in sets of 47, 88, 113 blocks

Most common is 88-piece set

Each set contains pair of 2 mm wearblocks

Used at end of buildup to prolong accuracy

of other blocks


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Degrees of Accuracy

Class AAA (Master laboratory set)

Also listed as Grade .5

Accurate to .000001 in. or 0.000025

mm.

Used in environmentally controlled labs

as master references for other gage

blocks


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Class AA (laboratory or master set)

Also listed as Grade 1

Accurate to .000002 in. or 0.00005

mm.

Used in temperature controlled labs as

references

Degrees of Accuracy


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Class A (inspection set)


Accurate to .000004 in.

and +0.00015 mm. and -0.00005 mm.

Used for inspection purposes

Degrees of Accuracy


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Class B (working set)


Accurate to .000008 in.

and +0.00025mm. and -0.00015 mm.

Used in shop for setups, layouts and

measurement

Degrees of Accuracy


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Effect of Temperature

Temperature changes important when

handling

Calibrated at 68F or 20C

Human body temperature 98F

One degree F rise will cause a four

inch stack of gage blocks to expand

.000025 in.

Handle as little as possible!


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Temperature-ChangeErrors Handle only when they must be moved

Hold by hand for as little time as possible

Hold between the tips of fingers so thatarea of contact is small

Have the work and gage blocks at thesame temperature

Where extreme accu racyis necessary,use insulating gloves and tweezers


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Gage Block Accessories


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Gage Block Constructions


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Gage Block Build-up

1 Write dimension on paper

2 Deduct size of two wear blocks3 Use block that will eliminate right

hand digit (Deduct 0.1006)

4 Use block that will eliminate right

hand digit (4) and at same time bring digit

to left of it (9) to zero or a five

5 Continue to eliminate digits from right

to left until dimension required attained

3.7946

(2 x .0500 in. = .1000 in.)

-0.1000

3.6946

-0.1006

3.594

(0.144)

-0.144

3.450

(0.450 block) Repeat with 3.000 block

-0.4503.000

-3.000

0.0


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Gage Block Build-up

1 Write dimension on paper

2 Deduct size of two wear blocks3 Use block that will eliminate right

hand digit (Deduct 0.1008)

4 Use block that will eliminate right

hand digit (2) and at same time bring digit

to left of it (4) to zero or a five

5 Continue to eliminate digits from right

to left until dimension required attained

1.6428

(2 x .0500 in. = .1000 in.)

-0.1000

1.5428

-0.1008

1.4420

(0.142)

-0.142

1.300

(0.300 block) Repeat with 1.000 block

-0.3001.000

-1.000

0.0


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Gage Block Buildups

Clean blocks with clean, soft cloth

Wipe each contacting surface on cleanhand palm or on wrist

Place end of one block over end ofanother block

While applying pressure, slide oneblock over other

Note: If blocks do not wring together, itis generally because blocks have notbeen thoroughly cleaned.


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Gage Block Wringing

Adhere to each other so well can

withstand 200-pound pull Atmospheric

pressure

Molecular attraction

Extremely flat surfaces of blocks

Minute film of oil

Combination of all above


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Wringing Gage Blocks


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Care of Gage Blocks

Keep in closed case to protect from dustand dirt

Do not handle unnecessarily

Avoid fingering lapped surfaces Do not drop or scratch their lapped

surfaces


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Care of Gage Blocks

Immediately after use, each blockshould be cleaned, oiled, and replacedin the storage case

Before wrung together, faces must befree from oil and dust

Should never be left wrung together for

any length of time


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Care of Gage Blocks


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