Multi Start Threading
Some photos of samples of multi start threading I did some years back. I hope that this will help illustrate multi start threading.
Left to right: single start 1"-3, single start 1"-12, double start 1"12, triple start 1"-12 and finally a quad start 1"-12 thread
Close up of the 1"-3 and the 1"12 single start.
Each nut has been turned one revolution from the end of the shaft. A single start 1"-12 thread has a lead of 1/12" or .0833l The double start has a lead of .1667, the triple start has a lead of .2499 and the triple start thread has a lead of .3332.
If you will go back to the picture above you will see the vale of multi start threads other than faster movement of the nut or shaft. The 1"-3 thread shown above has the same lead as the 1"-12 quad start thread to the right in the photo below. The multi start thread shaft has MUCH more strength that the single start 3TPI thread above.