These British manufactured High Speed Steel Ground Threading Dies, have a machined lead-in for ease of use and accurate thread cutting. These Dies are also split to facilitate the fine adjustment of core diameter. Please make your size selection from the drop down menu and select the O.D.(Outside Diameter)for the die from the letter list. Die O.D. Thread Size Range 13/16" (1/16" - 1/4") 1" (3/16" - 1/2") 1-5/16" (1/4" - 9/16") 1-1/2" (3/8" - 3/4") 2" (9/16" - 1") 3" (1-1/8" - 2")
B.S.W. (Whitworth) H.S.S. Dies 5/16" - 7/16"
- Tap Types: First Taper (or Taper Tap) A Taper Tap has a pronounced taper to the cutting edges. This feature gives the taper tap a very gradual cutting action that is less aggressive than that of the plug tap. The number of tapered threads typically ranges from 8 to 10. A taper tap is most often used when the material to be tapped is difficult to work (e.g., alloy steel) or the tap is of a very small diameter and thus prone to breakage. Second Taper (or Intermediate Taper) A Second Taper tap has tapered cutting edges, which assist in aligning and starting the tap into an untapped hole. The number of tapered threads typically ranges from 3 to 5 and is the most common type of threading tap used. Plug/Cleaning Tap (or Bottom Tap) A Plug tap has a continuous cutting edge with almost no taper — between 1 and 1.5 threads of taper. This feature enables a bottoming tap to cut threads to the bottom of a blind hole. A bottoming tap is usually used to cut threads in a hole that has already been partially threaded using one of the more tapered types of tap or for cleaning out dirty threads; the tapered end of a plug tap is too short to successfully start and cut new threads in an unthreaded hole.