Threading Application Guide TopThread™ Threading TopThread Square Shank Toolholder Sizes: Cresting (Full Profile):• Metric — 10–32mmUN TPI of 32–7 External Threading ISO 1,5–3,0mm pitch 60° Partial Profile — Flat Top (NTF and NTK): UN 44–4.5 TPI ISO 0,6–5,5mm pitch TopThread Boring Bar Diameters: Cresting (Full Profile):• Metric — 10–50mmUN 16–8 TPI Internal Threading • Minimum bore —11,5mm ISO 1,5–3,0mm pitch • Steel 60° Partial Profile — Flat Top (NT-1L, NTF, and NTK): UN 24–4.5 TPI ISO 1,0–5,5mm pitch F2 widia.com