Metric coarse
Tap drill 1.45 mm for a M1.8 × 0.35 thread - major Ø 1.8 mm, pitch 0.35 mm (≈72.57 TPI (converted)).
Profile
| Designation | M1.8 × 0.35 |
|---|---|
| Major (outside) diameter | 1.8 mm · 0.0709" |
| Pitch | 0.35 mm · ≈72.57 TPI (converted) |
| Pitch diameter | 1.573 mm · 0.0619" |
| Minor diameter (external) | 1.371 mm · 0.054" |
| Minor diameter (internal) | 1.421 mm · 0.0559" |
| Recommended tap drill | 1.45 mm · ≈77% thread |
| Clearance hole | Close 2 · Normal 2.1 · Loose 2.2 mm |
ISO 273 clearance holes (fine / medium / coarse).
Target preload is 75% of proof load; torque is estimated from T = K · F · d.
| Grade / class | Stress area | Preload | Torque |
|---|---|---|---|
| Class 8.8 | 1.7 mm² | 0.74 kN | 0.27 N·m |
| Class 10.9 | 1.7 mm² | 1.06 kN | 0.38 N·m |
| Class 12.9 | 1.7 mm² | 1.24 kN | 0.45 N·m |
Strengths are ISO 898-1:2013 Table 3 for d ≤ 16 mm. Class 8.8 is size-banded - 580 MPa proof at or below 16 mm, 600 MPa above - while 10.9 and 12.9 hold one value across the range.
The bolt schedule collects the fasteners for one job onto a single sheet - tap drill, wrench size, grade and tightening torque on every line, taken straight from pages like this one. Free schedules hold 3 lines and are saved in this browser only.
For a M1.8 × 0.35 thread, drill the hole with a 1.45 mm tap drill (1.45 mm - the standard D − P rule) before tapping. That produces roughly 77% thread engagement, the usual target for a strong, tappable hole. The mating bolt has a major diameter of 1.8 mm and a pitch of 0.35 mm (≈72.57 TPI (converted)).
To pass a M1.8 × 0.35 bolt through a part rather than thread it, use a clearance hole: Close 2 · Normal 2.1 · Loose 2.2 mm.
All values are generated from the standard thread formulas (ISO 68-1 / ASME B1.1) and published standard tables - not hand-entered. See the full reference.
Drill 1.45 mm before tapping M1.8 × 0.35. That leaves roughly 77% thread engagement, the usual target for a strong hole that still taps cleanly.
M1.8 × 0.35 is a metric coarse thread. Coarse is the default pitch for M1.8: when a drawing or supplier says just M1.8, it means this 0.35 mm pitch.
Drill 2 mm for a close fit, 2.1 mm for a normal fit or 2.2 mm for a loose fit (ISO 273). A clearance hole lets the M1.8 × 0.35 bolt pass through the part instead of threading into it.
Estimated tightening torque for M1.8 × 0.35 runs from 0.27 N·m (Class 8.8) to 0.45 N·m (Class 12.9), targeting 75% of proof load with a dry nut factor of K = 0.20. Lubricated threads need noticeably less torque.
Closest inch sizes
Nearest standard Unified sizes by major diameter. These are substitutes by size only - the thread forms are not interchangeable, so never run one into the other.
Nearby sizes