I recently purchased a couple of spiral fluted taps because others here have said that they worked much better than the standard straight flute. They are correct. I tapped some blind 8-32 holes in aluminum and they indeed go in much easier. That was the problem. I am used to feeling when the tap reaches the bottom of the hole and then backing out. I was not careful enough and when I reached the bottom I thought that I just had to back up a bit to clear the chips and keep going. Unfortunately I kept on going and stripped out two of four holes. Fortunately in this case it is easy to just retap to 10-32 but it could have been a costly lesson. I will continue to use the taps and will probably buy more but I will be more cautious next time.