what I do is get a 5/16 u.n.c grubscrew 5/16 or 3/8 long soften it by heat it to red hot with a torch then let it cool in air . get a 5/16 unc nut cut one side so when you clamp it it will squeeze the grub screw ,then drill the grub screw with a 0.040" or 1 mm drill bit then debur the grub screw.
