Just a little info for those new to taps. Getting them perfectly vertical is bit of a pain. If you have a bench drill then setup the item to be tapped. Put the tap in the drill chuck, press it down lightly and wind it in a turn or two by hand twisting the chuck. Then release the tap from the chuck and continue by hand on the bench. You can do the same on a lathe by placing the tap in a drill chuck fitted to the tail stock, set the tail stock to slide freely and rotate the big chuck by hand.