M45 Thread Specs
Standard: ISO 261 (ISO Metric Coarse)
This reference guide outlines the technical dimensions and tapping parameters for the standard M45 metric thread.
Part of the ISO Metric Coarse series defined by ISO 261, the thread features a nominal diameter of 45 mm and a pitch of 4.5 mm.
For machining or fabrication, the recommended tap drill size is 40.5 mm (for 75% thread depth) or 40.78 mm (for 65% thread depth).
Dimensional Specifications (mm)
Nominal Diameter
45 mm
Pitch
4.5 mm
Threads per mm
0.22
Major Diameter
45 mm
Pitch Diameter (d₂)
42.077 mm
Minor Diameter (d₁) Ext
40.129 mm
Minor Diameter (D₁) Int
40.778 mm
Thread Height
3.897 mm
Root Radius
0.65 mm
Drilling & Strength Specs
Tap Drill (75%)
40.5 mm
Tap Drill (65%)
40.78 mm
Stress Area
1306 mm²
Stress Diameter
39.479 mm
Recommended Tightening Torque
| Property Class | Dry (Nm) | Lubricated (Nm) |
|---|---|---|
| Class 8.8 | 6500 | 4875 |
| Class 10.9 | 9560 | 7170 |
| Class 12.9 | 11470 | 8602.5 |
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Frequently Asked Questions
What is the tap drill size for a M45 thread?
For standard thread engagement (approx. 75%), the recommended tap drill size for M45 is 40.5 mm. For a slightly looser 65% thread engagement, a 40.78 mm drill bit is recommended.
What is the pitch of a M45 thread?
The thread pitch for a standard M45 thread is 4.5 mm, which equates to approximately 0.22 threads per millimeter.
What are the major and pitch diameters for M45?
The nominal major diameter of M45 is 45 mm. The calculated pitch diameter (d₂) is 42.077 mm per the ISO 68-1/ISO 261 standards.