chart for rod diameter for threading Practical Machinist
2016 3 8 nbsp 0183 32 May be it comes 0 001 to 0 002 undersize fine Nobody will take foot long sections of 1 2 inch dia rod and turn it down A good die will have no problem cutting a thread on a rod 0 500 quot in dia I have never has a problem with running a 1 4 20 5 16 18 5 16 24 3 8 16 or any other die over a full size dia rod