1-1/2-6 UNC Thread Specs
Standard: ASME B1.1 (UNC)
Find the technical dimensions, threads per inch (TPI), and tapping guidelines for the 1-1/2-6 UNC unified thread.
Compliant with the ASME B1.1 standard, this size has a nominal major diameter of 1.5 inches (38.1 mm) with a pitch of 0.16667 inches (TPI of 6).
For general engineering or fastening, the standard recommended tap drill is 1.3333 inches (33.87 mm) to achieve adequate thread engagement.
Dimensional Specifications (Inches & mm)
Size Designation
1-1/2-6 UNC
Major Diameter (Nominal)
1.5 in(38.1 mm)
TPI (Threads per Inch)
6
Pitch
0.16667 in
Pitch Diameter
1.3917 in(35.35 mm)
Minor Diameter (Ext)
1.3196 in(33.52 mm)
Minor Diameter (Int)
1.3376 in(33.98 mm)
Thread Height
0.1443 in
Drilling & Strength Specs
Tap Drill Size
1.3333 in(33.87 mm)
Stress Area
1.4052 in²(906.61 mm²)
Quick Unit Converter
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Frequently Asked Questions
What is the tap drill size for 1-1/2-6 UNC?
The recommended tap drill size for a 1-1/2-6 UNC thread is 1.3333 inches (approx. 33.87 mm) to achieve standard thread engagement.
How many threads per inch (TPI) does a 1-1/2-6 UNC bolt have?
A standard 1-1/2-6 UNC thread has exactly 6 threads per inch (TPI), with a corresponding linear pitch of 0.16667 inches.
What is the major diameter of a 1-1/2-6 UNC thread in millimeters?
The nominal major diameter of a 1-1/2-6 UNC thread is 1.5 inches, which converts to 38.1 mm.