What is the Major Diameter of roundstock if i have to thread it at 32 threads per inch?

Answer 1

Is this using a standard die?
There are many sizes 3/8x32, 5/16x32, 1/4x32, 12x32, 10x32, 8x32, 6x32.
It depends on what you want it to fit 8x32 and 6x32 are the common and the round stock would be
UNC 0.164 for 8 and 0.138 for 6
UNF 10 is 0.190
UNEF 12=0.216, 1/4=0.2500, 5/16=0.3125, 3/8=0.375