Metric fine

M48 × 1.5

Tap drill 46.5 mm for a M48 × 1.5 thread — major Ø 48 mm, pitch 1.5 mm (16.93 TPI).

Tap drill
46.5 mm
46.5 mm · ≈77% thread

Profile

Thread form & key diameters

Major Ø 48 mmP 1.5 mm60°Minor Ø 46.16 mm · Pitch Ø 47.026 mmM48 × 1.516.93 TPI · 60° form

Dimensions

DesignationM48 × 1.5
Major (outside) diameter48 mm · 1.8898"
Pitch1.5 mm · 16.93 TPI
Pitch diameter47.026 mm · 1.8514"
Minor diameter (external)46.16 mm · 1.8173"
Minor diameter (internal)46.376 mm · 1.8258"
Recommended tap drill46.5 mm · ≈77% thread
Clearance holeClose 50 · Normal 52 · Loose 56 mm
Hex head (across flats)75 mm
Socket key (across flats)36 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 8.81705 mm²741.68 kN7120.1 N·m
Class 10.91705 mm²1061.37 kN10189.1 N·m
Class 12.91705 mm²1240.39 kN11907.8 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 M48 × 1.5?

For a M48 × 1.5 thread, drill the hole with a 46.5 mm tap drill (46.5 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 48 mm and a pitch of 1.5 mm (16.93 TPI).

To pass a M48 × 1.5 bolt through a part rather than thread it, use a clearance hole: Close 50 · Normal 52 · Loose 56 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

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