So I have a spot in my basement where there are exposed beams that hold up the floor and what not above. I'd like to attach a pipe somehow for pull ups. Should I try to bolt it to the bottom of the rafters (rafters may not be the technically correct term here). Or should I attempt to drill through several of them and run the pipe through the hole. I would like to not break my house. The rafters look like 6"x2" (or maybe 8x2) boards and are about a foot apart.

What kind of diameter pipe is ideal for pull ups?