ACME Thread data sheet

0.625-8 ACME - Basic Thread Dimensions

Property Inch mm
Major Diameter (D) 0.625 15.875
Pitch (TPI) (P) 8 8
Pitch (Distance) (P) 0.125 3.175
Pitch Diameter (D2) 0.5625 14.288
Minor Diameter (D1) 0.5 12.7
Thread Height (h) 0.0625 1.588
Flat Width (F) 0.0463 1.176
Profile V Angle (2 X α) 29° 29°
Lead Angle (λ) 4.046° 4.046°
Tap Drill Size (Dt) 0.5 12.7
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


0.625-8 ACME Possible Thread Classes

The data listed below is valid only for Single Start Threads and engagement lengthsup to 1.25 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

5/8 - 8 ACME 2G (External)

* Permisable values forthread Class 2G

# Description Value (Inch) Value (mm)
d Major Diameter 0.6187 - 0.625 15.715 - 15.875
d2 Pitch Diameter 0.5409 - 0.5562 13.739 - 14.127
d1 Minor Diameter 0.457 - 0.48 11.608 - 12.192
P Varation of Pitch (+/-) 0.0007 0.018
α Varation of 14.5° anngle (+/-) 0.58°

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5/8 - 8 ACME 3G (External)

* Permisable values forthread Class 3G

# Description Value (Inch) Value (mm)
d Major Diameter 0.6187 - 0.625 15.715 - 15.875
d2 Pitch Diameter 0.5506 - 0.5578 13.985 - 14.168
d1 Minor Diameter 0.4693 - 0.48 11.92 - 12.192
P Varation of Pitch (+/-) 0.0007 0.018
α Varation of 14.5° anngle (+/-) 0.58°

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5/8 - 8 ACME 4G (External)

* Permisable values forthread Class 4G

# Description Value (Inch) Value (mm)
d Major Diameter 0.6187 - 0.625 15.715 - 15.875
d2 Pitch Diameter 0.5542 - 0.5593 14.077 - 14.206
d1 Minor Diameter 0.4723 - 0.48 11.996 - 12.192
P Varation of Pitch (+/-) 0.0007 0.018
α Varation of 14.5° anngle (+/-) 0.58°

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5/8 - 8 ACME 2C (External)

* Permisable values forthread Class 2C

# Description Value (Inch) Value (mm)
d Major Diameter 0.6222 - 0.625 15.804 - 15.875
d2 Pitch Diameter 0.5409 - 0.5562 13.739 - 14.127
d1 Minor Diameter 0.457 - 0.48 11.608 - 12.192
P Varation of Pitch (+/-) 0.0007 0.018
α Varation of 14.5° anngle (+/-) 0.58°

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5/8 - 8 ACME 3C (External)

* Permisable values forthread Class 3C

# Description Value (Inch) Value (mm)
d Major Diameter 0.6238 - 0.625 15.845 - 15.875
d2 Pitch Diameter 0.5506 - 0.5578 13.985 - 14.168
d1 Minor Diameter 0.4693 - 0.48 11.92 - 12.192
P Varation of Pitch (+/-) 0.0007 0.018
α Varation of 14.5° anngle (+/-) 0.58°

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5/8 - 8 ACME 4C (External)

* Permisable values forthread Class 4C

# Description Value (Inch) Value (mm)
d Major Diameter 0.6242 - 0.625 15.855 - 15.875
d2 Pitch Diameter 0.5542 - 0.5593 14.077 - 14.206
d1 Minor Diameter 0.4723 - 0.48 11.996 - 12.192
P Varation of Pitch (+/-) 0.0007 0.018
α Varation of 14.5° anngle (+/-) 0.58°

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5/8 - 8 ACME 2G ( Internal)

* Permisable values for thread Class 2G

# Description Value () Value ()
D Major Diameter 0.645 - 0.665 16.383 - 16.891
D2 Pitch Diameter 0.5625 - 0.5779 14.288 - 14.679
D1 Minor Diameter 0.5 - 0.5063 12.7 - 12.86
P Varation of Pitch (+/-) 0.0007 (Ref) 0.018 (Ref)
α Varation of 14.5° anngle (+/-) 0.58 (Ref) 14.732 (Ref)

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5/8 - 8 ACME 3G ( Internal)

* Permisable values for thread Class 3G

# Description Value () Value ()
D Major Diameter 0.645 - 0.665 16.383 - 16.891
D2 Pitch Diameter 0.5625 - 0.5697 14.288 - 14.47
D1 Minor Diameter 0.5 - 0.5063 12.7 - 12.86
P Varation of Pitch (+/-) 0.0007 (Ref) 0.018 (Ref)
α Varation of 14.5° anngle (+/-) 0.58 (Ref) 14.732 (Ref)

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5/8 - 8 ACME 4G ( Internal)

* Permisable values for thread Class 4G

# Description Value () Value ()
D Major Diameter 0.645 - 0.665 16.383 - 16.891
D2 Pitch Diameter 0.5625 - 0.5676 14.288 - 14.417
D1 Minor Diameter 0.5 - 0.5063 12.7 - 12.86
P Varation of Pitch (+/-) 0.0007 (Ref) 0.018 (Ref)
α Varation of 14.5° anngle (+/-) 0.58 (Ref) 14.732 (Ref)

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5/8 - 8 ACME 2C ( Internal)

* Permisable values for thread Class 2C

# Description Value () Value ()
D Major Diameter 0.6258 - 0.6286 15.895 - 15.966
D2 Pitch Diameter 0.5625 - 0.5779 14.288 - 14.679
D1 Minor Diameter 0.5125 - 0.5188 13.018 - 13.178
P Varation of Pitch (+/-) 0.0007 (Ref) 0.018 (Ref)
α Varation of 14.5° anngle (+/-) 0.58 (Ref) 14.732 (Ref)

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5/8 - 8 ACME 3C ( Internal)

* Permisable values for thread Class 3C

# Description Value () Value ()
D Major Diameter 0.6258 - 0.6286 15.895 - 15.966
D2 Pitch Diameter 0.5625 - 0.5697 14.288 - 14.47
D1 Minor Diameter 0.5125 - 0.5188 13.018 - 13.178
P Varation of Pitch (+/-) 0.0007 (Ref) 0.018 (Ref)
α Varation of 14.5° anngle (+/-) 0.58 (Ref) 14.732 (Ref)

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5/8 - 8 ACME 4C ( Internal)

* Permisable values for thread Class 4C

# Description Value () Value ()
D Major Diameter 0.6258 - 0.6274 15.895 - 15.936
D2 Pitch Diameter 0.5625 - 0.5676 14.288 - 14.417
D1 Minor Diameter 0.5125 - 0.5188 13.018 - 13.178
P Varation of Pitch (+/-) 0.0007 (Ref) 0.018 (Ref)
α Varation of 14.5° anngle (+/-) 0.58 (Ref) 14.732 (Ref)

* Back to Thread Class Selection


Over Wire Measurements for 0.625-8 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 0.06133 - 0.09683 1.5577 - 2.4596
Ideal Wire Diameter 0.06456 1.6397
Possible Wires
From Standard Sets
* 0.06415
* 0.07217
* 0.07698
* 0.08248
* 0.09623
* 1.7321
* 2.0207
* 2.3094

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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