Workshop
ISO Metric Coarse
60° · 60° V · parallel
Tap drill
8.50 mm0.3346"Q (0.3320")
Workshop chart ≈ 75% engagement for fastening V-threads. Adjust for material and class of fit.
Clearance drill
ISO 273 medium / normal
Measure pitch diameter, not just major Ø. A thread can mic correctly on the crests and still be undersize on d2.
ISO 68 / 261 / 724 / 965 · Charts are guidance — confirm critical work against the standard.