You need a long tap or drill the hole out 1 size larger than the barrel of the tap and just thread the bottom. You will still run into a issue because tap extensions (so you can get to the bottom of the hole) are fairly large.Started tapping a hole in my aluminum slant manifold but the tap was about one inch too short. What is used to tap deeper? I need to go down about 3 1/2 inches. What do you guys use?
A socket will be almost twice as big as the tap. You would have to bore a pretty large hole.What about thin-wall 8-point or spline-drive sockets in 1/4" drive? The OP didn't state what size tap..???
That's what she said!3/8-16 actually need to go down a hair longer than two inches
What He said....................Can you show us what you are trying to tap?