INDEXABLE DRILLS · USER GUIDE Pre-Thread DCT Drills There are two main applications for pre-thread hole drilling: Drilling pre-thread blind and through holes: Drilling with a 45° Chamfer Drilling and Counter Boring 6 mm max Pre-Thread DCT Metric Threads Recommended Diameters Drill Designation Dia. Range M Thread HeadDia. MF Head Head Dia. TRThreadHead Dia. M HelicoilThreadHead Dia. DCT 068-021-14B-M8 6.80-7.49 M8   6.8 MF8X0.75   7.20 TR10X3   7.49MF8X1  7.00 DCT 085-026-14B-M10 8.30-8.99 M10   8.5 MF10X1   8.99 TR10X1.5   8.60MF10X1.25  8.80M8   8.40 M12 10.2 MF11X1 10.00 TR12X2 10.20 M10 10.50 DCT 102-030-14B-M12 10.0-10.99 MF12X1 10.99 TR14X4 10.50MF12X1.2510.80 MF12X1.5 10.50 M14 12.0 MF13X1 12.00 TR14X2 12.20 M12 12.50 DCT 120-035-16B-M14 12.0-12.99 MF14X1 12.99 TR16X4 12.30MF14X1.2512.80 MF14X1.5 12.50 M16 14.0 MF14X1 14.00 TR18X4 14.30 M14 14.99 DCT 140-039-18B-M16 14.0-14.99 MF16X1 14.99 MF16X1.5 14.50 DCT 175-042-20B-M20 17.3-17.99 M20 17.5 MF20X2 TR22X5 17.3017.99 DCT 210-048-25B-M24 21.0-21.99 M24 21.0 MF22X1 21.00 Inch Threads Drill Designation Dia.Range UNFThreadHeadDia. UNC Thread Head UNC Helicoil HeadDia.ThreadDia.BSWThreadHeadDia.BSF ThreadHeadDia. DCT 085-026-14B-M10   8.30-8.99UNF3/8-24   8.5 UNC5/16-18 8.4 DCT 102-030-14B-M12 10.0-10.99 UNC1/2-13 10.8   BSW1/2-12 10.5 BSF1/2-16 10.99 DCT 120-035-16B-M14 12.0-12.99 UNC9/16-12 12.3 BSF9/16-16 12.50 DCT 140-039-18B-M16 14.0-14.99UNF5/8-18 14.5   DCT 175-042-20B-M20 17.3-17.99UNF3/4-16 17.5 Inch Threads Drill Designation Dia.Range NPTThreadHeadDia.BSF Thread HeadDia. BSPThreadHeadDia.UNEF Thread Head UNJF Helicoil HeadDia.ThreadDia. DCT 085-026-14B-M10   8.30-8.99 NPT1/8-27   8.5 G1/8-28 8.8 UNEF3/8-32   8.7 UNJF3/8-24   8.6 DCT 102-030-14B-M12 10.0-10.99 BSF1/2-16 10.99 DCT 120-035-16B-M14 12.0-12.99 BSF9/16-16 12.50 DCT 140-039-18B-M16 14.0-14.99 NPT3/8-18 14.5 UNEF5/8-24 14.8 UNJF5/8-18 14.5 DCT 175-042-20B-M20 17.3-17.99 NPT1/2-14 17.5 UNEF3/4-20 17.8 135