Tap Drill Chart 1/2x13 Tap Drill Size
.4062. M16 x 1.5. 14.50 .5709 .4130 .1040. 5-44. 27. M18 x 2.5. 15.50 .6102 .4219. 1/2-13 .1065. 6 32. 64. 7. M18 x 1.5. 16.50 .6496 .4375. 64 .1094. Setting the base of my barrel vise up with a 27/64 drill bit to later be tapped for 1/2-13 threads. I'd try two things for wood - one, pick a drill size “slightly” larger than the one specified for 60% threads in metal. Two, as mentioned ...