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BreakingChips

ISO metric · fine

M3.5 × 0.35 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

3.2 mm

0.1260" · 66% thread

Form tap

3.3 mm

0.1299" · 84% thread

Open M3.5 × 0.35 in the calculator

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

Thread dimensions

Major Ø
3.500 mm (0.1378")
Pitch
0.35 mm
Pitch Ø (basic)
3.273 mm (0.1288")
Minor Ø (internal, basic)
3.121 mm (0.1229")
Thread depth (internal)
0.189 mm (0.0075")

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 M3.5 × 0.35
DrillØ inØ mmThread
1/80.12503.1871%
3.2 mmsuggested0.12603.2066%
#300.12853.2652%

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 M3.5 × 0.35
DrillØ inØ mmThread
3.3 mm0.12993.3084%

3-wire measurement

Best wire size
0.202 mm (0.0080")
Over wires, at basic pitch Ø
3.576 mm (0.1408")

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

Sources