Phil,
Not a dumb question at all. 4 turns per inch is just that, the amount of turning to get the nut to travel one inch. The threads per inch, again are just that (as in any common screw thread ie. 1/4-20 is a 1/4" Dia screw with 20 threads per inch). The "Starts" refer to engagement of the threads. When the nut engages the threads, it does so 180 deg's apart. You can have different amounts of starts (usually even numbers). So, a 4 start will engage the nut in four places (90 degrees apart) and so on.
Regards,
Glen |