I need to tap a very short hole, about 4mm deep. I was thinking of using a thread forming tap. Tap size is m5 x .80 (4.6mm drill for 70% DOT) I read that thread forming taps must be used on a DP or mill. Can they not be hand/wrench tapped? Most taps don't have enough starting threads.,( like tapping sheet metal) the hole is on a 1/2" OD x 8mm ID, so not a lot of tapping room. Not a blind hole. If not a thread forming tap, what type of tap is best for such a short hole?