28. Thread Series Production data ■Unifined Threads ■Conversion Table Size Nominal Dia. Threads per inch Column Column inch Coarse Fine Extra Fine Constant pitch series Threads per inch 1 2 (25.4mm) Pitch (mm) 1/ 4 5/ 16 3/ 8 7/ 16 1/ 2 9/ 16 5/ 8 /11 16 3/ 4 /13 16 7/ 8 /15 16 1 11/ 16 11/ 8 13/ 16 11/ 4 15/ 16 13/ 8 17/ 16 11/ 2 19/ 16 15/ 8 111/ 16 13/ 4 113/ 16 17/ 8 115/ 16 2 21/ 8 21/ 4 23/ 8 21/ 2 25/ 8 23/ 4 27/ 8 3 31/ 8 31/ 4 33/ 8 31/ 2 35/ 8 33/ 4 37/ 8 4 41/ 8 41/ 4 43/ 8 41/ 2 45/ 8 43/ 4 47/ 8 5 51/ 8 51/ 4 53/ 8 51/ 2 55/ 8 53/ 4 57/ 8 6 : Please select the first column by priority. And select second column and third column if necessary. General size list of metric trapezoidal threads nit mm Technical Information When the tap for the trapezoidal threads not listed in the catalogue is required, please contance Yamawa sales. Technical-81 852