ThreadRef

Sizes · Metric (ISO)

Metric coarse

M45 × 4.5

Tap drill 40.5 mm for a M45 × 4.5 thread — major Ø 45 mm, pitch 4.5 mm (5.64 TPI).

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Tap drill
40.5 mm
40.5 mm · ≈77% thread

Profile

Thread form & key diameters

Major Ø 45 mmP 4.5 mm60°Minor Ø 39.479 mm · Pitch Ø 42.077 mmM45 × 4.55.64 TPI · 60° form

Dimensions

DesignationM45 × 4.5
Major (outside) diameter45 mm · 1.7717"
Pitch4.5 mm · 5.64 TPI
Pitch diameter42.077 mm · 1.6566"
Minor diameter (external)39.479 mm · 1.5543"
Minor diameter (internal)40.129 mm · 1.5799"
Recommended tap drill40.5 mm · ≈77% thread
Clearance holeClose 46 · Normal 48 · Loose 51 mm
Hex head (across flats)70 mm

ISO 273 clearance holes (fine / medium / coarse).

Tightening torque estimate

Target preload is 75% of proof load; torque is estimated from T = K · F · d.

Grade / classStress areaPreloadTorque
Class 8.81306 mm²568.11 kN5113 N·m
Class 10.91306 mm²812.99 kN7316.9 N·m
Class 12.91306 mm²950.12 kN8551 N·m
These figures assume a nut factor of K = 0.20 (dry / as-received steel). K captures thread and head friction and can swing torque by 30% or more — a lubricated joint needs noticeably less. Change the lubrication assumption in the bolt-torque calculator.

What tap drill do I need for M45 × 4.5?

For a M45 × 4.5 thread, drill the hole with a 40.5 mm tap drill (40.5 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 45 mm and a pitch of 4.5 mm (5.64 TPI).

To pass a M45 × 4.5 bolt through a part rather than thread it, use a clearance hole: Close 46 · Normal 48 · Loose 51 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.

Same diameter

Other M45 threads

M45 × 1.5Tap 43.5 mmØ 45 mm · pitch 1.5 mmM45 × 2.0Tap 43 mmØ 45 mm · pitch 2 mmM45 × 3.0Tap 42 mmØ 45 mm · pitch 3 mmM45 × 4.0Tap 41 mmØ 45 mm · pitch 4 mm

Nearby sizes

More metric coarse threads

M42 × 4.5Tap 37.5 mmØ 42 mm · pitch 4.5 mmM48 × 5.0Tap 43 mmØ 48 mm · pitch 5 mmM39 × 4.0Tap 35 mmØ 39 mm · pitch 4 mmM52 × 5.0Tap 47 mmØ 52 mm · pitch 5 mmM36 × 4.0Tap 32 mmØ 36 mm · pitch 4 mmM56 × 5.5Tap 50.5 mmØ 56 mm · pitch 5.5 mmM33 × 3.5Tap 29.5 mmØ 33 mm · pitch 3.5 mmM30 × 3.5Tap 26.5 mmØ 30 mm · pitch 3.5 mm