It's drill and tap. the only time you want to use the drill is when you drilling a hole. not for the actual tapping. that is how the taps break and the gunsmith makes money.
after you have the proper size hole for the tap, (no drill...only by hand -->)twist it by the handle gently until it stops itself inside the hole, then back it out a 1/4 turn, then go forward 1/2 turn, then back out a 1/4 turn, use tap oil on every twist forward. it will get a little messy, so do it on a thick rag and don't worry about using to much oil, you want it wet, but not overflowing.... repeat that process until you have tapped through the hole. also while twisting out the 1/4 turns take a small brush and remove any shavings that come out. after you have completely tapped the hole, twist the tap through completely and back out then blow air through the hole with a compressor to remove any chips.
careful of splattering oil where the wife will clearly see that you have not taken care of splattering oil on the curtains and ream you a new hole, yet not where you expected it to be....true story.