M30 Thread Specs
Standard: ISO 261 (ISO Metric Coarse)
This reference guide outlines the technical dimensions and tapping parameters for the standard M30 metric thread.
Part of the ISO Metric Coarse series defined by ISO 261, the thread features a nominal diameter of 30 mm and a pitch of 3.5 mm.
For machining or fabrication, the recommended tap drill size is 26.5 mm (for 75% thread depth) or 26.72 mm (for 65% thread depth).
Dimensional Specifications (mm)
Nominal Diameter
30 mm
Pitch
3.5 mm
Threads per mm
0.29
Major Diameter
30 mm
Pitch Diameter (d₂)
27.727 mm
Minor Diameter (d₁) Ext
26.211 mm
Minor Diameter (D₁) Int
26.716 mm
Thread Height
3.031 mm
Root Radius
0.505 mm
Drilling & Strength Specs
Tap Drill (75%)
26.5 mm
Tap Drill (65%)
26.72 mm
Stress Area
560.59 mm²
Stress Diameter
25.706 mm
Recommended Tightening Torque
| Property Class | Dry (Nm) | Lubricated (Nm) |
|---|---|---|
| Class 8.8 | 1760 | 1320 |
| Class 10.9 | 2589 | 1941.8 |
| Class 12.9 | 3107 | 2330.3 |
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Frequently Asked Questions
What is the tap drill size for a M30 thread?
For standard thread engagement (approx. 75%), the recommended tap drill size for M30 is 26.5 mm. For a slightly looser 65% thread engagement, a 26.72 mm drill bit is recommended.
What is the pitch of a M30 thread?
The thread pitch for a standard M30 thread is 3.5 mm, which equates to approximately 0.29 threads per millimeter.
What are the major and pitch diameters for M30?
The nominal major diameter of M30 is 30 mm. The calculated pitch diameter (d₂) is 27.727 mm per the ISO 68-1/ISO 261 standards.