1-1/8-7 UNC Thread Specs
Standard: ASME B1.1 (UNC)
Find the technical dimensions, threads per inch (TPI), and tapping guidelines for the 1-1/8-7 UNC unified thread.
Compliant with the ASME B1.1 standard, this size has a nominal major diameter of 1.125 inches (28.58 mm) with a pitch of 0.14286 inches (TPI of 7).
For general engineering or fastening, the standard recommended tap drill is 0.9821 inches (24.95 mm) to achieve adequate thread engagement.
Dimensional Specifications (Inches & mm)
Size Designation
1-1/8-7 UNC
Major Diameter (Nominal)
1.125 in(28.58 mm)
TPI (Threads per Inch)
7
Pitch
0.14286 in
Pitch Diameter
1.0322 in(26.22 mm)
Minor Diameter (Ext)
0.9704 in(24.65 mm)
Minor Diameter (Int)
0.9858 in(25.04 mm)
Thread Height
0.1237 in
Drilling & Strength Specs
Tap Drill Size
0.9821 in(24.95 mm)
Stress Area
0.7633 in²(492.43 mm²)
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Frequently Asked Questions
What is the tap drill size for 1-1/8-7 UNC?
The recommended tap drill size for a 1-1/8-7 UNC thread is 0.9821 inches (approx. 24.95 mm) to achieve standard thread engagement.
How many threads per inch (TPI) does a 1-1/8-7 UNC bolt have?
A standard 1-1/8-7 UNC thread has exactly 7 threads per inch (TPI), with a corresponding linear pitch of 0.14286 inches.
What is the major diameter of a 1-1/8-7 UNC thread in millimeters?
The nominal major diameter of a 1-1/8-7 UNC thread is 1.125 inches, which converts to 28.58 mm.