Many common ball joints use a 7-degree taper, which is also expressed as 1-1/2 inches of taper per foot. Speedway Motors had the reamer we needed for the task. Its three-sided shank meant that it fit perfectly in our half-inch drill chuck, and the reverse spiral flute pattern means smooth, controlled cutting. The cutting edge of the reamer still cuts in the clockwise direction, but the spiral pattern is reversed. That way, the reamer is not trying to pull itself into the material as the reamer is rotated.