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M3.5×0.6 — Full Fastener Spec
ISO 68-1 / ISO 261 · Coarse series · Tap drill, clearance hole, torque, strength and tool sizes — every number on one page.
Tap drill (75% thread)
2.9 mm
Nearest inch drill: #33 (0.1130") · Clearance hole (normal fit): 3.9 mm ·
8.8 torque: 2.06 N·m dry
Thread dimensions
Major diameter
3.5 mm
Pitch
0.6 mm
TPI (equivalent)
42.33
Pitch diameter
3.11 mm
Minor diameter
2.851 mm
Tensile stress area
6.78 mm²
Tap drill sizes for M3.5×0.6
Percent of thread is a trade-off: 75% is the shop default because the last 25% of engagement adds only a few percent of strength while roughly doubling tapping torque. Drop to 50–65% in tough or gummy material, or for blind holes where a snapped tap means scrapping the part.
| Thread engagement | Exact | Metric drill | Nearest inch drill |
|---|---|---|---|
| 50% | 3.11 mm | 3.1 mm | 0.1200" (#31 drill) |
| 65% | 2.993 mm | 3 mm | 0.1200" (#31 drill) |
| 75% | 2.915 mm | 2.9 mm | 0.1130" (#33 drill) |
| 85% | 2.837 mm | 2.8 mm | 0.1100" (#35 drill) |
Roll (form) taps need a larger hole than cut taps — add roughly
0.4× the pitch to the 75% cut-tap drill and confirm against your tap maker's chart.
Clearance hole for M3.5×0.6
| Fit | Hole | Use |
|---|---|---|
| Close | 3.7 mm | Located joints, dowel-like alignment |
| Normal | 3.9 mm | General assembly — use this unless you have a reason not to |
| Loose | 4.2 mm | Weldments, sheet stacks, tolerance build-up |
M3.5×0.6 torque specs
Calculated with the short-form equation T = K · D · F, using K = 0.2 (plain, dry, as-received steel) and a target clamp load of 75% of proof load — the standard preload target for a reusable joint.
| Grade | Dry | Lubricated | Dry (lb-ft) | Clamp load |
|---|---|---|---|---|
| 4.6 Low-carbon steel, general purpose | 0.8 N·m | 0.6 N·m | 0.59 lb-ft | 1.1 kN |
| 8.8 Medium-carbon, quenched & tempered — the default structural grade | 2.06 N·m | 1.55 N·m | 1.52 lb-ft | 2.9 kN |
| 10.9 Alloy steel, Q&T — high strength | 2.95 N·m | 2.21 N·m | 2.18 lb-ft | 4.2 kN |
| 12.9 Alloy steel, Q&T — highest common grade (socket head cap screws) | 3.45 N·m | 2.59 N·m | 2.54 lb-ft | 4.9 kN |
| A2-70 304 stainless, cold worked | 1.6 N·m | 1.2 N·m | 1.18 lb-ft | 2.3 kN |
The nut factor K dominates this result. Zinc-plated, waxed, anti-seize
and lubricated threads all shift K between roughly 0.10 and 0.25, which is a 2.5×
spread in torque for identical preload. If preload actually matters, torque-to-yield,
angle control or a load-indicating washer beats a torque wrench every time.
Tool sizes
Hex head wrench
6 mm