Tap Drills for Pipe Threads Diameter Length Size Drill 27 R 18 18 14 14 8 3-1/2 8 4 4.38712 1.3000 844 4.500 4.23438 4-1/4 FIGURE 12-31. American (National) pipe thread dimensions and tap drill sizes.
Diameter Soft Mild Malleable Hard Cast Tool or Alloy Steel of Drill Metals Steel Iron Iron Hard Steel Cast Steel 300 F.P.M. 100 F.P.M. 90 F.P.M. 80 F.P.M. 60 F.P.M. 40 F.P.M.
1/16 (No. 53 to 80) 18320 3667 2445 3/32 (No. 42 to 52) 122:2 2442 1649 1/8 (No. 31 to 41) 9180 1833 1222 5/32 (No. 23 to 30) 7328 1465 977 3/16 (No. 13 to 22) 6106 1222 815 7/32 (No. I to 12) 5234 1047 698 1/4 (A to E) 4575 917 611 9/32 (G to K) 4071 814 542 9/16 (L, M, N) 3660 733 489 11/32 (O to R) 3330 666 444 3/8 (S, T, U) 3050 611 407 13/32 (V to Z) 2818 563 376 7/16 2614 1222 524 349 15/32 2442 1140 652 488 326 1/2 2287 1528 1070 764 688 611 458 306 9/16 2035 1357 950 678 611 543 407 .: 271 3/8 1830 1222 856 611 550 489 367 244 11/16 1665 1110 777 555 500 444 333 222 3/4 1525 1018 713 509 458 407 306 204 Figures are for High-Speed Drills. The spced of Carbon Drills should be reduced one-half.
Use drill speed nearest to figure given.
FIGURE 12-32. Drill speeds.