Pre-Plate pitch diameters, major diameters, and minor diameters of thread rings, thread plugs, and plug gauges.
The rules for determining Pre-Plate pitch diameters, major diameters, and minor diameters of thread rings, thread plugs, and plug gauges are as follows: |
To determine Pre-Plating dimensions
for external threaded parts:
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For
external threads subtract the max plating thickness from the high limit Pitch
Diameter, and then subtract the minimum plating from the low limit Pitch
Diameter
|
For the
minor and major diameters reduce the maximum diameters by half the maximum
plating and reduce minimum diameter by half the minimum plating.
|
To determine Pre-Plating dimensions
for internal threaded parts:
|
For
internal threads add the max plating thickness to the low limit of the Pitch
Diameter, and then add the minimum plating thickness to the high limit of
the Pitch Diameter. For minor and major diameters increase the minimum
minor diameters by half the maximum plating and increase the maximum minor
diameter by half the minimum plating.
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To determine Pre-Plating dimensions
for thread ring gauges:
|
For thread
ring gauges subtract the max plating thickness from the Pitch Diameter of the
Go thread ring gauge. Then subtract the minimum plating from the Pitch
Diameter of the No-Go thread ring gauge. For the minor diameter reduce the
Go ring minor diameter by half the maximum plating and reduce the No Go ring
minor diameter by half the minimum plating.
|
To determine pre plating dimensions
for thread plug gages:
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For thread
plug gauges add the max plating thickness to the Pitch Diameter of the Go
thread plug gauge. Add the minimum plating thickness to the Pitch
Diameter of the No-Go thread plug gauge. Increase the major diameter of the Go
thread plug by half the maximum plating and increase the No Go thread plug
major diameter by half the minimum plating.
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Example for Thread Plug Gage:
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Plating of
.0002” - .0003” allowance per side multiple x 4
|
.0003 x 4
= .0012” Max
.0002 x 4 = .0008” Min |
½ - 20 UNF 2B Pre-Plate
|
Basic standard
Go Pitch Diameter = .4675” + .0012” = .4687” Go Pre-Plate Pitch
diameter.
Basic standard No Go Pitch Diameter = .4731” + .0008” = .4739” No Go Pre-Plate Pitch Diameter. |
Basic standard
Go Major Diameter = .5000” + .0006” = .5006” Go Pre-Plate Major Diameter.
Basic standard No Go Major Diameter = .4948” + .0004” = .4952” No Go Pre-Plate Major Diameter. |
Example for Thread Ring gages:
|
Plating of
.0002” - .0003” allowance per side multiple x 4
|
.0003 x 4
= .0012” Max
.0002 x 4 = .0008” Min |
.0003 x 4
= .0012” Max
.0002 x 4 = .0008” Min |
½ - 20 UNF
2A
|
Basic standard
Go Pitch Diameter = .4662” - .0012” = .4650” Go Pre-Plate Pitch Diameter
Basic standard No Go Pitch Diameter = .4619” - .0008” = .4611” No Go Pre-Plate Pitch Diameter |
Basic standard
Go Minor Diameter = .4446” - .0006” = .4440” Go Pre Plate Minor Diameter.
Basic standard No Go Minor Diameter = .4511” - .0004” = .4507” No Go Pre-Plate Minor Diameter. |
If no
minimum and maximum plating thickness is given, then the given plating
thickness is considered nominal or minimum plus 50% to determine maximum
plating.
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