Thread data sheet

Basic Thread Dimensions

Property Inch mm
Nominal Diameter 0.875 22.225
Pitch (TPI)32
Pitch (Distance) 0.0313 0.795
Pitch Diameter 0.8547 21.709
Minor Diameter 0.8378 21.28
Thread Height 0.0169 0.429
Addendum 0.0101 0.257
Crest (External)
Root (Internal)
0.0039 0.099
Tap Drill Size
(75% depth)
0.844 21.45
Lead Angle
(Single Start)
0.67°
Thread Family Unified Constant Pitch 32 TPI (32-UN)
Relevant Standards ASME B1.1-2003
Equivalent MetricThreadM22 X 1

For more threading data scroll down, or use the Thread Calculator

Choose the Threading Data you want to explore


7/8 - 32 32-UNPossible Thread Classes

External Threads

2A, 3A

Metric ISO External Thread - Tolerance sketch

Internal Threads

2B, 3B

Metric ISO Internal Thread - Tolerance sketch

7/8 - 32 32-UN 2A (External)

* Permisable values for thread Class 2A

# Description Value (Inch) Value (mm)
es Allowance 0.0011 (Ref) 0.028 (Ref)
d Major Diameter 0.8679 - 0.8739 22.045 - 22.197
d2 Pitch Diameter 0.8501 - 0.8536 21.593 - 21.681
d3 Minor Diameter
(UNR Only)
0.8367 (Ref) 21.252 (Ref)
α Varation of 30° anngle (+/-) 1.5°
P Varation of pitch (+/-) 0.001 (Ref) 0.025 (Ref)

* Values are calculated for Length of engagement of 5xPitch. For calculations of different engagement length use the Thread Calculator'

* Back to Thread Class Selection


7/8 - 32 32-UN 3A (External)

* Permisable values for thread Class 3A

# Description Value (Inch) Value (mm)
es Allowance 0 (Ref) 0 (Ref)
d Major Diameter 0.869 - 0.875 22.073 - 22.225
d2 Pitch Diameter 0.8521 - 0.8547 21.643 - 21.709
d3 Minor Diameter
(UNR Only)
0.8378 (Ref) 21.28 (Ref)
α Varation of 30° anngle (+/-) 1.5°
P Varation of pitch (+/-) 0.0008 (Ref) 0.02 (Ref)

* Values are calculated for Length of engagement of 5xPitch. For calculations of different engagement length use the Thread Calculator'

* Back to Thread Class Selection


7/8 - 32 32-UN 2B (Internal)

* Permisable values for thread Class 2B

# Description Value (Inch) VValue (mm)
D1 Minor Diameter 0.841 - 0.849 21.361 - 21.565
D2 Pitch Diameter 0.8547 - 0.8593 21.709 - 21.826
D Major Diameter 0.8750 (Min) 22.225 (Min)
α Varation of 30° anngle (+/-) 1.5°
P Varation of Pitch (+/-) 0.0013 (Ref) 0.033 (Ref)

* Values are calculated for Length of engagement of 5xPitch. For calculations of different engagement length use the Thread Calculator

* Back to Thread Class Selection


7/8 - 32 32-UN 3B (Internal)

* Permisable values for thread Class 3B

# Description Value (Inch) VValue (mm)
D1 Minor Diameter 0.8412 - 0.8469 21.366 - 21.511
D2 Pitch Diameter 0.8547 - 0.8581 21.709 - 21.796
D Major Diameter 0.8750 (Min) 22.225 (Min)
α Varation of 30° anngle (+/-) 1.5°
P Varation of Pitch (+/-) 0.001 (Ref) 0.025 (Ref)

* Values are calculated for Length of engagement of 5xPitch. For calculations of different engagement length use the Thread Calculator

* Back to Thread Class Selection


Tap Drill Sizes for 7/8 - 32 32-UN

  • If not specified, assume a thread depth of 75%.
  • You can learn more about thread depth in tapping here.
  • To get the tap drill size in other depths, use our Tap Drill Size Calculator .
Thread Depth Tap Drill Size (Inch) Tap Drill Size (mm)
55% 0.853 21.66
60% 0.851 21.61
65% 0.849 21.55
70% 0.847 21.50
75% 0.845 21.45
80% 0.843 21.40
85% 0.840 21.35

Over Wire Measurements for 7/8 - 32 32-UN


* OverWire is a measuring method to obatin the pitch diameter of threads. It is mostly used when a manufacturer does not have a Go/Nogo gauge for a thread. You can learn more about it here

Inch mm
Permissible Wire Diameter Range 0.0158 - 0.0316 0.402 - 0.803
Ideal Wire Diameter 0.0181 0.459
Possible Wires
From Standard Sets
* 0.016
* 0.018
* 0.0193
* 0.0206
* 0.0214
* 0.0222
* 0.0241
* 0.0262
* 0.0289
* 0.404
* 0.433
* 0.462
* 0.52
* 0.577
* 0.722

Once you know your wire diameter, you need to find out what is the premissable Measurement for your pitch diameter (Depending on the class). Use our Over Wire Calculator to find out!


CNC Gcode Program for Turning of 7/8 - 32 32-UN

The below sample Gcode is configured for:

  • Fanuc Controller
  • External RH Thread
  • Right hand tool, machining towards the chuck
  • Flank Infeed method with contant volume
  • Flank Infeed method with contant volume
  • Cutting conditions for steel
  • Default number of passes

You can configure all the above parameters and much more in our Thread Turning Gcode Generator


%
O0100
(MACHINING DOCTOR - THREADING CNC PROGRAM)
(CONTROLER - FANUC A)
(THREAD - )
(D=0.875 INCH, P=0.031 INCH, L=0.313 INCH)
(APPLICATION - EXTERNAL TURNING, TOWARDS CHUCK, RH TOOL, RH THREAD)
(FEED - 17 PASSES, FLANK, CONSTANT VOLUME)
(FINISH PASS - 0.0003 INCH)
(WITH CHAMFER -  NO)
G28 U0
G28 U0
T0100
G99 G97 S1310 M03
G00 Z5.1
G00 X27.5 M08
G76 P010060 Q8 R0
G76 X21 Z-8 P487 Q116 F1 R
G28 U0
G28 U0
M09
M30
(PLEASE NOTE THIS GCODE HAS NOT BEEN TESTED ON YOUR MACHINE AND SETUP. WE CANNOT GUARANTEE ITS ACCURACY OR COMPATIBILITY. NOTE THAT YOU ARE USING IT AT YOUR OWN RISK, AND WE SHALL NOT BE HELD LIABLE FOR ANY DAMAGES OR LOSSES ARISING FROM THE USE OF THIS PROGRAM.)
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CNC Gcode Program for Thread Milling of 7/8 - 32 32-UN

The below sample Gcode is configured for:

  • Fanuc Controller
  • Internal RH Thread
  • Climb Milling
  • Cutter diameter: 70% of the thread diameter
  • Single tooth Thread Mill cutter
  • Cutting conditions for steel
  • One radial pass

You can configure all the above parameters and much more in our Thread Milling Gcode Generator


%
O0101
(WWW.MACHININGDOCTOR.COM - THREADMILLING PROGRAM)
(CONTROLER - FANUC)
(THREAD - MAJOR DIAM.=0.875 INCH, PITCH=0.03125 INCH, LENGTH=0.3125 INCH)
(APPLICATION - INTERNAL, RH THREAD, CLIMB MILLING)
(CUTTER DIAM=0.4375 [SINGLE TOOTH])
(CUTTER COMPENSATION D=0 - TOOLPATH FOR TOOL CENTER)
N1 M06 T1
G54
G90 G40 G17 G94 G21
G00 X0 Y0 S2619 M03
G43 H1 Z25.4 M08
(M-CODE "THROUGH COOLANT ON")
(PASS 1 / 1)
G90 G01 Z-8.0367 F2032
G91 G01 G41 D1 X2.7781 Y-2.7781 F399
G03 X2.7781 Y2.7781 Z0.0992 I0 J2.7781 F100
G03 Z0.7938 I-5.5563 J0 F200
G03 Z0.7938 I-5.5563 J0
G03 Z0.7938 I-5.5563 J0
G03 Z0.7938 I-5.5563 J0
G03 Z0.7938 I-5.5563 J0
G03 Z0.7938 I-5.5563 J0
G03 Z0.7938 I-5.5563 J0
G03 Z0.7938 I-5.5563 J0
G03 Z0.7938 I-5.5563 J0
G03 Z0.7938 I-5.5563 J0
G03 X-2.7781 Y2.7781 Z0.0992 I-2.7781 J0
G01 G40 X-2.7781 Y-2.7781 F2032
G90 G00 Z25.4
M30
(PLEASE NOTE THIS GCODE HAS NOT BEEN TESTED ON YOUR MACHINE AND SETUP. WE CANNOT GUARANTEE ITS ACCURACY OR COMPATIBILITY. NOTE THAT YOU ARE USING IT AT YOUR OWN RISK, AND WE SHALL NOT BE HELD LIABLE FOR ANY DAMAGES OR LOSSES ARISING FROM THE USE OF THIS PROGRAM.)
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