Hand Threading and Reaming - Multi start thread
Video
A multi-start thread consists of two or more intertwined threads running parallel to one another. Intertwining threads allow the lead distance of a thread to be increased without changing its pitch. A double start thread will have a lead distance double that of a single start thread of the same pitch, a triple start thread will have a lead distance three times longer than a single start thread of the same pitch, and so on
 
The following is an example of a two start thread with a pitch of 1.5 mm.
 

Lead  = Pitch x No of starts
          = 1.5 x 2
          = 3 mm
USE
  • Multi-start threads are used for transmitting power and generating movement. Because each partial or complete revolution equals more linear travel based on the number of threads, multi-threaded components can efficiently handle more power.
  • Multi-start threads can also be used for some fastening purposes