M8x1 Thread Specs
Standard: ISO 261 (ISO Metric Fine)
This reference guide outlines the technical dimensions and tapping parameters for the standard M8x1 metric thread.
Part of the ISO Metric Fine series defined by ISO 261, the thread features a nominal diameter of 8 mm and a pitch of 1 mm.
For machining or fabrication, the recommended tap drill size is 7 mm (for 75% thread depth) or 7.06 mm (for 65% thread depth).
Dimensional Specifications (mm)
Nominal Diameter
8 mm
Pitch
1 mm
Threads per mm
1
Major Diameter
8 mm
Pitch Diameter (d₂)
7.35 mm
Minor Diameter (d₁) Ext
6.917 mm
Minor Diameter (D₁) Int
7.062 mm
Thread Height
0.866 mm
Root Radius
0.144 mm
Drilling & Strength Specs
Tap Drill (75%)
7 mm
Tap Drill (65%)
7.06 mm
Stress Area
39.17 mm²
Stress Diameter
6.773 mm
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Frequently Asked Questions
What is the tap drill size for a M8x1 thread?
For standard thread engagement (approx. 75%), the recommended tap drill size for M8x1 is 7 mm. For a slightly looser 65% thread engagement, a 7.06 mm drill bit is recommended.
What is the pitch of a M8x1 thread?
The thread pitch for a standard M8x1 thread is 1 mm, which equates to approximately 1 threads per millimeter.
What are the major and pitch diameters for M8x1?
The nominal major diameter of M8x1 is 8 mm. The calculated pitch diameter (d₂) is 7.35 mm per the ISO 68-1/ISO 261 standards.