Basic Thread Dimensions
Property | Inch | mm |
---|---|---|
Nominal Diameter | 2.75 | 69.85 |
Pitch (TPI) | 4 | |
Pitch (Distance) | 0.25 | 6.35 |
Pitch Diameter | 2.5876 | 65.725 |
Minor Diameter | 2.4523 | 62.288 |
Thread Height | 0.1353 | 3.437 |
Addendum | 0.0812 | 2.062 |
Crest (External) Root (Internal) |
0.0313 | 0.795 |
Tap Drill Size (75% depth) |
2.506 | 63.66 |
Lead Angle (Single Start) |
1.76° |
Thread Family | Unified Coarse Pitch (UNC) | |
Relevant Standards | ASME B1.1-2003 | |
Equivalent MetricThread | M70 X 6 |
For more threading data scroll down, or use the Thread Calculator
Choose the Threading Data you want to explore
2 3/4 - 4 UNCPossible Thread Classes
2 3/4 - 4 UNC 1A (External)
* Permisable values for thread Class 1A
# | Description | Value (Inch) | Value (mm) |
---|---|---|---|
es | Allowance | 0.0029 (Ref) | 0.074 (Ref) |
d | Major Diameter | 2.7114 - 2.7471 | 68.87 - 69.776 |
d2 | Pitch Diameter | 2.5701 - 2.5847 | 65.281 - 65.651 |
d3 | Minor Diameter (UNR Only) | 2.4494 (Ref) | 62.215 (Ref) |
α | Varation of 30° anngle (+/-) | 0.6667° | |
P | Varation of pitch (+/-) | 0.0042 (Ref) | 0.107 (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
2 3/4 - 4 UNC 2A (External)
* Permisable values for thread Class 2A
# | Description | Value (Inch) | Value (mm) |
---|---|---|---|
es | Allowance | 0.0029 (Ref) | 0.074 (Ref) |
d | Major Diameter | 2.7233 - 2.7471 | 69.172 - 69.776 |
d2 | Pitch Diameter | 2.575 - 2.5847 | 65.405 - 65.651 |
d3 | Minor Diameter (UNR Only) | 2.4494 (Ref) | 62.215 (Ref) |
α | Varation of 30° anngle (+/-) | 0.6667° | |
P | Varation of pitch (+/-) | 0.0028 (Ref) | 0.071 (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
2 3/4 - 4 UNC 3A (External)
* Permisable values for thread Class 3A
# | Description | Value (Inch) | Value (mm) |
---|---|---|---|
es | Allowance | 0 (Ref) | 0 (Ref) |
d | Major Diameter | 2.7262 - 2.75 | 69.245 - 69.85 |
d2 | Pitch Diameter | 2.5803 - 2.5876 | 65.54 - 65.725 |
d3 | Minor Diameter (UNR Only) | 2.4523 (Ref) | 62.288 (Ref) |
α | Varation of 30° anngle (+/-) | 0.6667° | |
P | Varation of pitch (+/-) | 0.0021 (Ref) | 0.053 (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
2 3/4 - 4 UNC 1B (Internal)
* Permisable values for thread Class 1B
# | Description | Value (Inch) | VValue (mm) |
---|---|---|---|
D1 | Minor Diameter | 2.479 - 2.517 | 62.967 - 63.932 |
D2 | Pitch Diameter | 2.5876 - 2.6066 | 65.725 - 66.208 |
D | Major Diameter | 2.7500 (Min) | 69.85 (Min) |
α | Varation of 30° anngle (+/-) | 0.6667° | |
P | Varation of Pitch (+/-) | 0.0055 (Ref) | 0.14 (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
2 3/4 - 4 UNC 2B (Internal)
* Permisable values for thread Class 2B
# | Description | Value (Inch) | VValue (mm) |
---|---|---|---|
D1 | Minor Diameter | 2.479 - 2.517 | 62.967 - 63.932 |
D2 | Pitch Diameter | 2.5876 - 2.6003 | 65.725 - 66.048 |
D | Major Diameter | 2.7500 (Min) | 69.85 (Min) |
α | Varation of 30° anngle (+/-) | 0.6667° | |
P | Varation of Pitch (+/-) | 0.0037 (Ref) | 0.094 (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
2 3/4 - 4 UNC 3B (Internal)
* Permisable values for thread Class 3B
# | Description | Value (Inch) | VValue (mm) |
---|---|---|---|
D1 | Minor Diameter | 2.4794 - 2.5094 | 62.977 - 63.739 |
D2 | Pitch Diameter | 2.5876 - 2.5971 | 65.725 - 65.966 |
D | Major Diameter | 2.7500 (Min) | 69.85 (Min) |
α | Varation of 30° anngle (+/-) | 0.6667° | |
P | Varation of Pitch (+/-) | 0.0027 (Ref) | 0.069 (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
Over Wire Measurements for 2 3/4 - 4 UNC
* 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 | 0.1263 - 0.2526 | 3.208 - 6.416 |
Ideal Wire Diameter | 0.1443 | 3.666 |
Possible Wires From Standard Sets |
* 0.1283 * 0.1443 * 0.165 * 0.1777 * 0.1925 * 0.21 |
* 3.464 * 4.042 * 4.619 * 5.196 * 5.774 |
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 2 3/4 - 4 UNC
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=2.75 INCH, P=0.25 INCH, L=2.5 INCH)
(APPLICATION - EXTERNAL TURNING, TOWARDS CHUCK, RH TOOL, RH THREAD)
(FEED - 17 PASSES, FLANK, CONSTANT VOLUME)
(FINISH PASS - 0.0023 INCH)
(WITH CHAMFER - NO)
G28 U0 W0
T0101 G99 G97 S139 M03
G00 Z10.2
X 80.0 M08
G76 P010060 Q58 R0.058
G76 X62.059 Z-63.5 P3895 Q931 F6.35 R0.00
G28 U0 W0
M09
M30
%