The document discusses different types of gauges used to check part dimensions, including: 1) Limit gauges which check that dimensions fall within upper and lower limits using "go" and "not go" gauges. 2) Plug, ring, taper, thread, form, radius, and feeler gauges which are used to check specific geometric features like holes, diameters, tapers, threads, profiles, radii, and clearances. 3) Indicating gauges which magnify dimensional deviations from specifications to precisely measure geometry and positioning of surfaces.

3. 4. According to their purposes :
 (a) Workshop Gauge:To Check Dimension
after manufacture
 (b) Inspection Gauge:To check part before
final acceptance
 (d) Purchase Inspection Gauge:To check
part of other factory
 (c) Reference or master gauges:To check
the dimension of Gauge

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Limit Gauge
• Limit gauges are made to the limits of the dimensions of the
part to be tested.There are two limit of dimensions, so we
need two limit gauge.
• ‘Go gauge’ should pass through or over a part while ‘Not Go
gauge 'should not pass through or over the part.

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Design of Limit Gauge
• Allocation ofTolerance
– ManufacturingTolerance
–Wear Allowance
•Taylor’s Principle of gauge Design
• Fixing of Gauge elements with handles
–Taper lock design
–Trilock Design
• Provision of Guards
• Provision of Pilot CorrectCentering
• Materials
• Hardness and Surface finish
• Rigidity
• Alignment of Gauge faces

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Allocation ofTolerance
Manufacturing Tolerance
• It is economically impractical to attempt to make “Go” and “Not Go”
gauges exactly to the two limits of work tolerance.
• Limit gauges are made 10 times more accurate than the tolerances
they are going to control.

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Allocation of MfgTolerance

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Allocation ofTolerance
Wear Allowance
•The surface of “Go” gauge is constantly rub
against the surface of the part in inspection and loose
their initial size.
•The size of plug gauge is reduced but size of snap
gauge is increased.
• 10% wear allowance is provided only for the “GO”
gauge if working tolerance is greater than 0.09 mm.

14. Materials which are used for making gauges are high carbon
and alloy steels, cemented carbides, etc.

15. Plug Gauges : These are used for checking holes of many
different shapes and sizes.
Ring Gauges : External diameter measuring gauges.
Taper Gauges :Taper testing gauges.
Snap Gauges :These are used for checking shafts.
Thread Gauges : These are used for pitch diameter of the
thread.
Form Gauges : These are used to check the contour of a
profile.
Feeler Gauges : For checking the clearance between the
mating surfaces.
Indicating Gauges : To measure the position of the
surfaces.

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Classification of Plain Gauge
According to the form of the tested surface :
(a) Plug gauges for checking holes.
(b) Snap and ring gauges for checking shafts.

25. TAPER GAUGE
 The most satisfactory method of testing a
taper is to use taper gauges.
 They are also used to gauge the diameter of
the taper at some point.
 Taper gauges are made in both the plug and
ring styles and, in general, follow the same
standard construction as plug and ring
gauges.

27. THREAD GAUGE
 Thread gauges are used to check the pitch
diameter of the thread.
 For checking internal threads (nut, bushes,
etc.), plug thread gauges are used, while for
checking external threads (screws, bolts,
etc.), ring thread gauges are used.
 Single-piece thread gauges serve for
measuring small diameters.
 For large diameters the gauges are made
with removable plugs machined with a tang.

30. FORM GAUGE
 Form gauges may be used to check the
contour of a profile of work piece for
conformance to certain shape or form
specifications.
Template Gauge
 It is made from sheet steel. It is also called
profile gauge.A profile gauge may contain
two outlines that represent the limits within
which a profile must lie

32. SCREW PITCH GAUGE
 Screw pitch gauges areused in picking out a
required screw and for checking the pitch of
the screw threads.
 They consist of a number of flat blades which
are cut out to a given pitch and pivoted in a
holder.
 Each blade is stamped with the pitch or
number of thread per inch and the holder
bears an identifying number designing the
thread it is intended for.

34. RADIUS AND FILLET GAUGE
 The function of these gauges is to check the
radius of curvature of convex and concave
surfaces over a range from 1 to 25 mm.
 The gauges are made in sets of thin plates
curved to different radius at the ends.
 Each set consists of 16 convex and 16 concave
blades.

36. FEELER GAUGE
 Feeler gauges are used for checking
clearances between mating surfaces.
 They are made in form of a set of steel,
precision machined blade 0.03 to 1.0 mm
thick and 100 mm long.
 Each blade has an indication of its thickness.
 To find the size of the clearance, one or two
blades are inserted and tried for a fit between
the contacting surfaces until blades of
suitable thickness are found.

38. INDICATING GAUGES
 Indicating gauges employ a means to
magnify how much a dimension deviates,
plus or minus, from a given standard to which
the gauge has been set.
 They are intended for measuring errors in
geometrical form and size, and for testing
surfaces for their true position with respect to
one another.
 Indicating gauges can be of a dial or lever
type.