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MJ· Aerospace / High-Fatigue

MJ36 x 3

Aerospace / High-Fatigue

Dimensionally an M thread at the pitch diameter -- same 60 degree flank, same pitch-diameter formula -- but the root is cut to a controlled minimum radius (rather than M's unspecified, often flat-truncated root) so the thread can survive repeated fatigue cycling. Used across aerospace and other high-fatigue fastening. Pitch-diameter and tolerance math is identical to M; the radius is a manufacturing and inspection requirement this database records but does not turn into a different basic diameter.

Standard
ISO 5855 / MIL-S-8879
Flank angle
60° included
Series
Fine pitch
Pitch
3.00 mm
Coarse default

Thread profile

Pitch line60°Pitch (P)Rounded crestRounded root

A 60 degree included flank angle, with a controlled root radius rather than a flat truncation -- the fatigue-resistant detail this diagram's rounded root stands in for.

Basic major 36.000 mm, pitch diameter 34.051 mm, minor diameter 32.752 mm -- theoretical dimensions at zero allowance, before any tolerance class is applied.

MJ fine sizes

Basic dimensions, MJ fine pitch
DesignationPitchMajor ØPitch ØMinor Ø
MJ8 x 11.00 mm8.00 mm7.350 mm6.917 mm
MJ10 x 1.251.25 mm10.00 mm9.188 mm8.647 mm
MJ12 x 1.251.25 mm12.00 mm11.188 mm10.647 mm
MJ14 x 1.51.50 mm14.00 mm13.026 mm12.376 mm
MJ16 x 1.51.50 mm16.00 mm15.026 mm14.376 mm
MJ18 x 1.51.50 mm18.00 mm17.026 mm16.376 mm
MJ20 x 1.51.50 mm20.00 mm19.026 mm18.376 mm
MJ22 x 1.51.50 mm22.00 mm21.026 mm20.376 mm
MJ24 x 22.00 mm24.00 mm22.701 mm21.835 mm
MJ27 x 22.00 mm27.00 mm25.701 mm24.835 mm
MJ30 x 22.00 mm30.00 mm28.701 mm27.835 mm
MJ33 x 22.00 mm33.00 mm31.701 mm30.835 mm
MJ36 x 33.00 mm36.00 mm34.051 mm32.752 mm

Designation calculator

MJØ36 mmP 3 mmNo tolerance class

Try “M12x1.5-6g”, “M8” (coarse pitch assumed), “MJ6-4h6h”, or “Tr20x4-8H”. Add “-LH” for a left-hand thread.

Calculated live

Pitch diameter (basic)34.051 mmAdd a tolerance class (e.g. -6g) for max/min limits
Major diameter
36.000 mm
Pitch diameter
34.051 mm
Minor diameter
32.752 mm
Tap drill
33.50 mm (33.564 mm calculated)
Clearance drill (normal)
37.00 mm (36.800 mm calculated)

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