The following charts list the largest thread pitch that can be applied on internal applications using TopThread threading inserts for 60° V-threadi

The following charts list the largest thread pitch that can be applied on internal applications using TopThread threading inserts for 60° V-threading and Acme threading. m mm nominal thread size (maximum diameter) 1 minimum minor diameter (minimum bore) It Metric-sized 60° V-Threading Limits internal threading limitations NT-1, NT-2 60° V-threading inserts Acme Threading Limits internal threading limitations NA and NAS-2, -3, -4, and -6 Acme threading inserts TPI nominal thread size minimum thread diameter (mm) NT-1 NT-2 NT-1 NT-2 4,00 M48 x 4.00 - 43,67 - 3,00 M42 x 3.00 - 38,75 - 2,50 M39 x 2.50 M24 x 2,50 36,29 21,29 2,00 M33 x 2.00 M15 x 2,00 30,84 12,84 1,75 M32 x 1.75 M15 x 1,75 30,11 13,11 1,50 M32 x 1.50 M15 x 1,50 30,38 13,38 1,25 M29 x 1.29 M14 x 1,25 27,65 12,65 1,00 M27 x 1.00 M14 x 1,00 25,92 12,92 0,75 M22 x 0.75 M12 x 0,75 21,19 11,19 Thread pitch of 1mm and less can be cut with an NT-2 insert provided the core thread diameter is 25mm or larger (11mm or larger with NT-1). internal threading limitations NT-3 and NT-4 60° V-threading inserts TPI nominal thread size minimum thread diameter (mm) 6,00 M76 x 6.00 69,50 5,50 M73 x 5.50 67,05 5,00 M70 x 5.00 64,59 4,00 M64 x 4.00 59,67 3,00 M52 x 3.00 48,75 2,50 M48 x 2.50 45,29 2,00 M42 x 2.00 39,84 1,75 M40 x 1.75 38,11 1,50 M38 x 1.50 36,38 Thread pitch of 1,5mm and less can be cut provided core thread diameter is 35mm or larger. NT-4-insert only. TPI nominal thread size minimum thread diameter (mm) NT-1 NT-1 NT-2 2 5 4.500 114.3 2-1/2 4-1/2 4.100 104.1 3 4 3.665 93.1 4 3-1/2 3.250 82.6 5 3 2.800 71.1 6 2-1/2 2.333 59.3 8 2-1/4 2.125 54.0 10 2 1.900 48.3 12 1-3/4 1.667 42.4 14 1-5/8 1.554 39.5 16 1-1/2 1.438 36.5 Sixteen threads per inch and finer can be cut provided minor diameter is 36,5mm or larger. NA-6 insert only. Additional secondary clearance can be ground on leading edge of insert to provide sufficient helical clearance for machining coarser threads and multiple start threads. Modified standard inserts may be furnished for machining threads outside of the limits shown. Technical Information TopThread Widia