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BreakingChips

ISO metric · coarse

M3 × 0.5 tap drill size

For general work, OSG suggests 65–70% of full thread. Harder materials and deep holes want less; the calculator sets it from your material.

Cut tap

2.6 mm

0.1024" · 62% thread

Or #38 (0.1015") for 65%

Form tap

2.8 mm

0.1102" · 59% thread

Or 7/64 (0.1094") for 65%

Open M3 × 0.5 in the calculator

Pick your material for its % of thread, tapping RPM and the rigid-tap code.

Thread dimensions

Major Ø
3.000 mm (0.1181")
Pitch
0.5 mm
Pitch Ø (basic)
2.675 mm (0.1053")
Minor Ø (internal, basic)
2.459 mm (0.0968")
Thread depth (internal)
0.271 mm (0.0107")

Basic sizes of the 60° form. Tolerance classes (6H) set the limits around them.

Cut tap drills

For a cutting (fluted or spiral) tap. Every standard drill from 50% to 85% thread; suggested rows are in the 65–70% band.

Cut tap drills for M3 × 0.5
DrillØ inØ mmThread
#400.09802.4979%
2.5 mm0.09842.5077%
#390.09952.5373%
#38suggested0.10152.5865%
2.6 mm0.10242.6062%
#370.10402.6455%

Form tap drills

A form (roll) tap displaces metal instead of cutting it, so it needs a bigger hole. Every standard drill from 50% to 85% thread; suggested rows are in the 65–70% band.

Form tap drills for M3 × 0.5
DrillØ inØ mmThread
7/64suggested0.10942.7865%
#350.11002.7961%
2.8 mm0.11022.8059%
#340.11102.8253%

3-wire measurement

Best wire size
0.289 mm (0.0114")
Over wires, at basic pitch Ø
3.108 mm (0.1224")

For the external thread (the screw). The best wire touches the flanks at the pitch diameter.

Sources