ACME Thread data sheet

0.25-16 ACME - Basic Thread Dimensions

Property Inch mm
Major Diameter (D) 0.25 6.35
Pitch (TPI) (P) 16 16
Pitch (Distance) (P) 0.0625 1.588
Pitch Diameter (D2) 0.2188 5.558
Minor Diameter (D1) 0.1875 4.763
Thread Height (h) 0.03125 0.794
Flat Width (F) 0.0232 0.589
Profile V Angle (2 X α) 29° 29°
Lead Angle (λ) 5.197° 5.197°
Tap Drill Size (Dt) 0.1875 4.763
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

0.25-16 ACME Possible Thread Classes

The data listed below is valid only for Single Start Threads and engagement lengthsup to 0.5 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

1/4 - 16 ACME 2G (External)

* Permisable values forthread Class 2G

# Description Value (Inch) Value (mm)
d Major Diameter 0.245 - 0.25 6.223 - 6.35
d2 Pitch Diameter 0.2043 - 0.2148 5.189 - 5.456
d1 Minor Diameter 0.1618 - 0.1775 4.11 - 4.509
P Varation of Pitch (+/-) 0.0005 0.013
α Varation of 14.5° anngle (+/-) 0.78°

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1/4 - 16 ACME 3G (External)

* Permisable values forthread Class 3G

# Description Value (Inch) Value (mm)
d Major Diameter 0.245 - 0.25 6.223 - 6.35
d2 Pitch Diameter 0.2109 - 0.2158 5.357 - 5.481
d1 Minor Diameter 0.1702 - 0.1775 4.323 - 4.509
P Varation of Pitch (+/-) 0.0005 0.013
α Varation of 14.5° anngle (+/-) 0.78°

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1/4 - 16 ACME 4G (External)

* Permisable values forthread Class 4G

# Description Value (Inch) Value (mm)
d Major Diameter 0.245 - 0.25 6.223 - 6.35
d2 Pitch Diameter 0.2133 - 0.2168 5.418 - 5.507
d1 Minor Diameter 0.1723 - 0.1775 4.376 - 4.509
P Varation of Pitch (+/-) 0.0005 0.013
α Varation of 14.5° anngle (+/-) 0.78°

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1/4 - 16 ACME 2C (External)

* Permisable values forthread Class 2C

# Description Value (Inch) Value (mm)
d Major Diameter 0.2482 - 0.25 6.304 - 6.35
d2 Pitch Diameter 0.2043 - 0.2148 5.189 - 5.456
d1 Minor Diameter 0.1618 - 0.1775 4.11 - 4.509
P Varation of Pitch (+/-) 0.0005 0.013
α Varation of 14.5° anngle (+/-) 0.78°

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1/4 - 16 ACME 3C (External)

* Permisable values forthread Class 3C

# Description Value (Inch) Value (mm)
d Major Diameter 0.2492 - 0.25 6.33 - 6.35
d2 Pitch Diameter 0.2109 - 0.2158 5.357 - 5.481
d1 Minor Diameter 0.1702 - 0.1775 4.323 - 4.509
P Varation of Pitch (+/-) 0.0005 0.013
α Varation of 14.5° anngle (+/-) 0.78°

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1/4 - 16 ACME 4C (External)

* Permisable values forthread Class 4C

# Description Value (Inch) Value (mm)
d Major Diameter 0.2495 - 0.25 6.337 - 6.35
d2 Pitch Diameter 0.2133 - 0.2168 5.418 - 5.507
d1 Minor Diameter 0.1723 - 0.1775 4.376 - 4.509
P Varation of Pitch (+/-) 0.0005 0.013
α Varation of 14.5° anngle (+/-) 0.78°

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1/4 - 16 ACME 2G ( Internal)

* Permisable values for thread Class 2G

# Description Value () Value ()
D Major Diameter 0.26 - 0.27 6.604 - 6.858
D2 Pitch Diameter 0.2188 - 0.2293 5.558 - 5.824
D1 Minor Diameter 0.1875 - 0.1925 4.763 - 4.89
P Varation of Pitch (+/-) 0.0005 (Ref) 0.013 (Ref)
α Varation of 14.5° anngle (+/-) 0.78 (Ref) 19.812 (Ref)

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1/4 - 16 ACME 3G ( Internal)

* Permisable values for thread Class 3G

# Description Value () Value ()
D Major Diameter 0.26 - 0.27 6.604 - 6.858
D2 Pitch Diameter 0.2188 - 0.2237 5.558 - 5.682
D1 Minor Diameter 0.1875 - 0.1925 4.763 - 4.89
P Varation of Pitch (+/-) 0.0005 (Ref) 0.013 (Ref)
α Varation of 14.5° anngle (+/-) 0.78 (Ref) 19.812 (Ref)

* Back to Thread Class Selection

1/4 - 16 ACME 4G ( Internal)

* Permisable values for thread Class 4G

# Description Value () Value ()
D Major Diameter 0.26 - 0.27 6.604 - 6.858
D2 Pitch Diameter 0.2188 - 0.2223 5.558 - 5.646
D1 Minor Diameter 0.1875 - 0.1925 4.763 - 4.89
P Varation of Pitch (+/-) 0.0005 (Ref) 0.013 (Ref)
α Varation of 14.5° anngle (+/-) 0.78 (Ref) 19.812 (Ref)

* Back to Thread Class Selection

1/4 - 16 ACME 2C ( Internal)

* Permisable values for thread Class 2C

# Description Value () Value ()
D Major Diameter 0.2505 - 0.2523 6.363 - 6.408
D2 Pitch Diameter 0.2188 - 0.2293 5.558 - 5.824
D1 Minor Diameter 0.1938 - 0.1988 4.923 - 5.05
P Varation of Pitch (+/-) 0.0005 (Ref) 0.013 (Ref)
α Varation of 14.5° anngle (+/-) 0.78 (Ref) 19.812 (Ref)

* Back to Thread Class Selection

1/4 - 16 ACME 3C ( Internal)

* Permisable values for thread Class 3C

# Description Value () Value ()
D Major Diameter 0.2505 - 0.2523 6.363 - 6.408
D2 Pitch Diameter 0.2188 - 0.2237 5.558 - 5.682
D1 Minor Diameter 0.1938 - 0.1988 4.923 - 5.05
P Varation of Pitch (+/-) 0.0005 (Ref) 0.013 (Ref)
α Varation of 14.5° anngle (+/-) 0.78 (Ref) 19.812 (Ref)

* Back to Thread Class Selection

1/4 - 16 ACME 4C ( Internal)

* Permisable values for thread Class 4C

# Description Value () Value ()
D Major Diameter 0.2505 - 0.2515 6.363 - 6.388
D2 Pitch Diameter 0.2188 - 0.2223 5.558 - 5.646
D1 Minor Diameter 0.1938 - 0.1988 4.923 - 5.05
P Varation of Pitch (+/-) 0.0005 (Ref) 0.013 (Ref)
α Varation of 14.5° anngle (+/-) 0.78 (Ref) 19.812 (Ref)

* Back to Thread Class Selection

Over Wire Measurements for 0.25-16 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 0.03066 - 0.04842 0.7789 - 1.2298
Ideal Wire Diameter 0.03228 0.8199
Possible Wires
From Standard Sets		 * 0.866
* 1.0104
* 1.1547

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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