ACME Thread data sheet

2.25-3 ACME - Basic Thread Dimensions

Property Inch mm
Major Diameter (D) 2.25 57.15
Pitch (TPI) (P) 3 3
Pitch (Distance) (P) 0.33333 8.467
Pitch Diameter (D2) 2.0833 52.916
Minor Diameter (D1) 1.9167 48.684
Thread Height (h) 0.16667 4.233
Flat Width (F) 0.1236 3.139
Profile V Angle (2 X α) 29° 29°
Lead Angle (λ) 2.916° 2.916°
Tap Drill Size (Dt) 1.91667 48.683
Thread Family Leadscrew Inch Thread (ACME)
Relevant Standards ASME B1.5

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

Table of Content


2.25-3 ACME Possible Thread Classes

The data listed below is valid only for Single Start Threads and engagement lengthsup to 4.5 For Multiple Starts and large LE's use our ACME Thread Calculator 

External Threads

Choose tolerance class

2G, 3G, 4G, 2C, 3C, 4C

Acme External Thread - Tolerance sketch

Internal Threads

_e("Choose tolerance class","md_acme");

2G, 3G, 4G, 2C, 3C, 4C

ACME Internal Thread - Tolerance sketch

2 1/4 - 3 ACME 2G (External)

* Permisable values forthread Class 2G

# Description Value (Inch) Value (mm)
d Major Diameter 2.2333 - 2.25 56.726 - 57.15
d2 Pitch Diameter 2.045 - 2.0713 51.943 - 52.611
d1 Minor Diameter 1.8572 - 1.8967 47.173 - 48.176
P Varation of Pitch (+/-) 0.0011 0.028
α Varation of 14.5° anngle (+/-) 0.37°

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2 1/4 - 3 ACME 3G (External)

* Permisable values forthread Class 3G

# Description Value (Inch) Value (mm)
d Major Diameter 2.2333 - 2.25 56.726 - 57.15
d2 Pitch Diameter 2.0621 - 2.0743 52.377 - 52.687
d1 Minor Diameter 1.8782 - 1.8967 47.706 - 48.176
P Varation of Pitch (+/-) 0.0011 0.028
α Varation of 14.5° anngle (+/-) 0.37°

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2 1/4 - 3 ACME 4G (External)

* Permisable values forthread Class 4G

# Description Value (Inch) Value (mm)
d Major Diameter 2.2333 - 2.25 56.726 - 57.15
d2 Pitch Diameter 2.0686 - 2.0773 52.542 - 52.763
d1 Minor Diameter 1.8835 - 1.8967 47.841 - 48.176
P Varation of Pitch (+/-) 0.0011 0.028
α Varation of 14.5° anngle (+/-) 0.37°

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2 1/4 - 3 ACME 2C (External)

* Permisable values forthread Class 2C

# Description Value (Inch) Value (mm)
d Major Diameter 2.2447 - 2.25 57.015 - 57.15
d2 Pitch Diameter 2.045 - 2.0713 51.943 - 52.611
d1 Minor Diameter 1.8572 - 1.8967 47.173 - 48.176
P Varation of Pitch (+/-) 0.0011 0.028
α Varation of 14.5° anngle (+/-) 0.37°

* Back to Thread Class Selection


2 1/4 - 3 ACME 3C (External)

* Permisable values forthread Class 3C

# Description Value (Inch) Value (mm)
d Major Diameter 2.2477 - 2.25 57.092 - 57.15
d2 Pitch Diameter 2.0621 - 2.0743 52.377 - 52.687
d1 Minor Diameter 1.8782 - 1.8967 47.706 - 48.176
P Varation of Pitch (+/-) 0.0011 0.028
α Varation of 14.5° anngle (+/-) 0.37°

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2 1/4 - 3 ACME 4C (External)

* Permisable values forthread Class 4C

# Description Value (Inch) Value (mm)
d Major Diameter 2.2485 - 2.25 57.112 - 57.15
d2 Pitch Diameter 2.0686 - 2.0773 52.542 - 52.763
d1 Minor Diameter 1.8835 - 1.8967 47.841 - 48.176
P Varation of Pitch (+/-) 0.0011 0.028
α Varation of 14.5° anngle (+/-) 0.37°

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2 1/4 - 3 ACME 2G ( Internal)

* Permisable values for thread Class 2G

# Description Value () Value ()
D Major Diameter 2.27 - 2.29 57.658 - 58.166
D2 Pitch Diameter 2.0833 - 2.1097 52.916 - 53.586
D1 Minor Diameter 1.9167 - 1.9334 48.684 - 49.108
P Varation of Pitch (+/-) 0.0011 (Ref) 0.028 (Ref)
α Varation of 14.5° anngle (+/-) 0.37 (Ref) 9.398 (Ref)

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2 1/4 - 3 ACME 3G ( Internal)

* Permisable values for thread Class 3G

# Description Value () Value ()
D Major Diameter 2.27 - 2.29 57.658 - 58.166
D2 Pitch Diameter 2.0833 - 2.0956 52.916 - 53.228
D1 Minor Diameter 1.9167 - 1.9334 48.684 - 49.108
P Varation of Pitch (+/-) 0.0011 (Ref) 0.028 (Ref)
α Varation of 14.5° anngle (+/-) 0.37 (Ref) 9.398 (Ref)

* Back to Thread Class Selection


2 1/4 - 3 ACME 4G ( Internal)

* Permisable values for thread Class 4G

# Description Value () Value ()
D Major Diameter 2.27 - 2.29 57.658 - 58.166
D2 Pitch Diameter 2.0833 - 2.0921 52.916 - 53.139
D1 Minor Diameter 1.9167 - 1.9334 48.684 - 49.108
P Varation of Pitch (+/-) 0.0011 (Ref) 0.028 (Ref)
α Varation of 14.5° anngle (+/-) 0.37 (Ref) 9.398 (Ref)

* Back to Thread Class Selection


2 1/4 - 3 ACME 2C ( Internal)

* Permisable values for thread Class 2C

# Description Value () Value ()
D Major Diameter 2.2515 - 2.2568 57.188 - 57.323
D2 Pitch Diameter 2.0833 - 2.1097 52.916 - 53.586
D1 Minor Diameter 1.95 - 1.9667 49.53 - 49.954
P Varation of Pitch (+/-) 0.0011 (Ref) 0.028 (Ref)
α Varation of 14.5° anngle (+/-) 0.37 (Ref) 9.398 (Ref)

* Back to Thread Class Selection


2 1/4 - 3 ACME 3C ( Internal)

* Permisable values for thread Class 3C

# Description Value () Value ()
D Major Diameter 2.2515 - 2.2568 57.188 - 57.323
D2 Pitch Diameter 2.0833 - 2.0956 52.916 - 53.228
D1 Minor Diameter 1.95 - 1.9667 49.53 - 49.954
P Varation of Pitch (+/-) 0.0011 (Ref) 0.028 (Ref)
α Varation of 14.5° anngle (+/-) 0.37 (Ref) 9.398 (Ref)

* Back to Thread Class Selection


2 1/4 - 3 ACME 4C ( Internal)

* Permisable values for thread Class 4C

# Description Value () Value ()
D Major Diameter 2.2515 - 2.2545 57.188 - 57.264
D2 Pitch Diameter 2.0833 - 2.0921 52.916 - 53.139
D1 Minor Diameter 1.95 - 1.9667 49.53 - 49.954
P Varation of Pitch (+/-) 0.0011 (Ref) 0.028 (Ref)
α Varation of 14.5° anngle (+/-) 0.37 (Ref) 9.398 (Ref)

* Back to Thread Class Selection


Over Wire Measurements for 2.25-3 ACME


* 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 0.16354 - 0.25823 4.154 - 6.5589
Ideal Wire Diameter 0.17215 4.3726
Possible Wires
From Standard Sets
* 0.16496
* 0.17765
* 0.19245
* 0.20995
* 4.6188
* 5.1962
* 5.7735

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!


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