Page 233 - JBO-Katalog-2022

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MF
Use of Thread Gauges EG M
MJ

G
1. Inspection of parallel internal threads with GO and NOT GO thread plug gauges Rc, R
Pg
1.1 Use of GO thread plug gauge
A GO thread plug gauge checks the virtual size of the internal thread (gauging the virtual pitch diameter). UNC
This is effected by checking the minimum limit of the pitch diameter, taking into account pitch errors, UNF
UN
errors in flank angles and deviations of form, which produce an apparent reduction of the pitch diameter of UNJF
the workpiece (virtual pitch diameter). In addition, it checks the minimum limit of the major diameter and
also whether the length of straight flank is sufficient; i.e. that the rounding at the root of the profile does NPT
not encroach too far upon the flank of the thread. NPTF
This gauge does not check the minor diameter of the workpiece thread.
The GO thread plug gauge, when screwed by hand without using excessive force, shall enter the whole length of
the workpiece thread. If the entry is not possible, the workpiece thread does not comply with the specification.

1.2 Use of NOT GO thread plug gauge (with red ring)
A NOT GO thread plug gauge checks whether the actual pitch diameter exceeds the specified maximum size.

The NOT GO thread plug gauge, when screwed by hand without using excessive force, may enter into both
ends of the threaded part, but by not more than two turns of thread. If it can be screwed in by more than
two turns of thread, the workpiece thread does not comply with the specification.

2. Inspection of parallel external threads with GO and NOT GO thread ring gauges
M
2.1 Use of GO thread ring gauge MF
M keg.
A GO thread ring gauge checks the virtual size of the external thread (gauging the virtual pitch diameter); M taper
i.e. it checks the maximum material limit of the pitch diameter, taking into account deviations of form and
pitch errors and errors in flank angles, which produce an apparent enlargement of the pitch diameter (virtual G
pitch diameter) of the workpiece. It also checks that the maximum minor diameter has not been exceeded. BSW
BSF
DIN 477
The major diameter of the external thread is not checked by this gauge. R, BA, Pg
The GO thread ring gauge, when screwed by hand without using excessive force, shall pass over the whole length UNC
of the workpiece thread. If assembly is not possible, the workpiece thread does not comply with the specification. UNF
UNEF
UN, UNS
2.2 Use of NOT GO thread ring gauge (with red spot)
A NOT GO thread ring gauge is intended to check whether the actual pitch diameter of a workpiece exceeds NPSM
NPT
the specified minimum size. NPTF
Tr, Rd
A NOT GO thread ring gauge, when screwed by hand without using excessive force on the workpiece thread,
may enter on both sides but by not more than two turns of thread. If the gauge can be screwed onto the
workpiece by more than two turns of thread, the thread does not comply with the specification.

3. MultiCheck thread plug gauges
MultiCheck plug gauges enable the thread and its depth up to 4 x thread diam eter to be checked

simultaneously. Special versions for up to 6xD can be supplied.
Three types of MultiCheck are available with the following reading of accuracy:
MultiCheck Scale: 0.5 mm / MultiCheck Vernier: 0.1 mm / MultiCheck with digital display: 0.01 mm M
MF

G
BSW
BSF
R, Pg
MF-EL
UNC, UNF
UNEF
UN, UNS
UNJC
UNJF
233 NPT
NPTF
Tr
EG