I need to drill a one-inch hole through the cinder block wall from the outside to the basement. I have a star drill and decided to do a practice run on a surplus block. It cracked when the hole was about half through. I am thinking that this will not on the wall because the block will have compression from the blocks on each side of the wall -- but I would like to have someone who really knows if I am right or indulging in wishful thinking.

You are correct in thinking that the compression and the surrounding blocks should keep your foundation block from cracking. As long as you are putting the hole in the center of the cinder block cell (2 cells per block) then it should be an easy punch with the star drill. I actually use a regular hammer to make this size hole in block - one sharp hit and you have a nice, round hole. Then use the star drill or a piece of rebar to punch through the other side of the block.

thank you

actually, a little off center. look at your sample block of the same size... about 1 inch end on each end is a cross-block tie of concrete, and dead-center is another.

I can assure you that you are not going to drive a star bit cleanly through the block center when you hit that block reinforcement. drill it say 1-1/2 inches off center, no problem.

don't forget to rotate the star bit with each whack. about 1/8 turn so the odd hits go between the bars of the bit in the last whack, and the bit will continue to generate a round, controlled, clean hole.

ah.